Metal Nanoparticle-Based Biosensors for the Early Diagnosis of Infectious Diseases Caused by ESKAPE Pathogens in the Fight against the Antimicrobial-Resistance Crisis.

The species included in the ESKAPE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and the genus Enterobacter) have a high capacity to develop antimicrobial resistance (AMR), a health problem that is already among the leading causes of death and could kill 10 million people a year by 2050. The generation of new potentially therapeutic molecules has been insufficient to combat the AMR "crisis", and the World Health Organization (WHO) has stated that it will seek to promote the development of rapid diagnostic strategies. The physicochemical properties of metallic nanoparticles (MNPs) have made it possible to design biosensors capable of identifying low concentrations of ESKAPE bacteria in the short term; other systems identify antimicrobial susceptibility, and some have been designed with dual activity in situ (bacterial detection and antimicrobial activity), which suggests that, in the near future, multifunctional biosensors could exist based on MNPs capable of quickly identifying bacterial pathogens in clinical niches might become commercially available. This review focuses on the use of MNP-based systems for the rapid and accurate identification of clinically important bacterial pathogens, exhibiting the necessity for exhaustive research to achieve these objectives. This review focuses on the use of metal nanoparticle-based systems for the rapid and accurate identification of clinically important bacterial pathogens.

Metal nanoparticles and pesticides under global climate change: Assessing the combined effects of multiple abiotic stressors on soil microbial ecosystems.

The soil is a vital resource that hosts many microorganisms crucial in biogeochemical cycles and ecosystem health. However, human activities such as the use of metal nanoparticles (MNPs), pesticides and the impacts of global climate change (GCCh) can significantly affect soil microbial communities (SMC). For many years, pesticides and, more recently, nanoparticles have contributed to sustainable agriculture to ensure continuous food production to sustain the significant growth of the world population and, therefore, the demand for food. Pesticides have a recognized pest control capacity. On the other hand, nanoparticles have demonstrated a high ability to improve water and nutrient retention, promote plant growth, and control pests. However, it has been reported that their accumulation in agricultural soils can also adversely affect the environment and soil microbial health. In addition, climate change, with its variations in temperature and extreme water conditions, can lead to drought and increased soil salinity, modifying both soil conditions and the composition and function of microbial communities. Abiotic stressors can interact and synergistically or additively affect soil microorganisms, significantly impacting soil functioning and the capacity to provide ecosystem services. Therefore, this work reviewed the current scientific literature to understand how multiple stressors interact and affect the SMC. In addition, the importance of molecular tools such as metagenomics, metatranscriptomics, proteomics, or metabolomics in the study of the responses of SMC to exposure to multiple abiotic stressors was examined. Future research directions were also proposed, focusing on exploring the complex interactions between stressors and their long-term effects and developing strategies for sustainable soil management. These efforts will contribute to the preservation of soil health and the promotion of sustainable agricultural practices.

Metallic nanoparticles and treatment of cutaneous leishmaniasis: A systematic review.

BACKGROUND: Cutaneous leishmaniasis (LC) is an infectious vector-borne disease caused by parasites belonging to the genus Leishmania. Metallic nanoparticles (MNPs) have been investigated as alternatives for the treatment of LC owing to their small size and high surface area. Here, we aimed to evaluate the effect of MNPs in the treatment of LC through experimental, in vitro and in vivo investigations. METHODS: The databases used were MEDLINE/ PubMed, Scopus, Web of Science, Embase, and Science Direct. Manual searches of the reference lists of the included studies and grey literature were also performed. English language and experimental in vitro and in vivo studies using different Leishmania species, both related to MNP treatment, were included. This study was registered in PROSPERO (CRD42021248245). RESULTS: A total of 93 articles were included. Silver nanoparticles are the most studied MNPs, and L. tropica is the most studied species. Among the mechanisms of action of MNPs in vitro, we highlight the production of reactive oxygen species, direct contact of MNPs with the biomolecules of the parasite, and release of metal ions. CONCLUSION: MNPs may be considered a promising alternative for the treatment of LC, but further studies are needed to define their efficacy and safety.

Silver Nanoparticles In Situ Synthesized and Incorporated in Uniaxial and Core-Shell Electrospun Nanofibers to Inhibit Coronavirus.

In the present study, we sought to develop materials applicable to personal and collective protection equipment to mitigate SARS-CoV-2. For this purpose, AgNPs were synthesized and stabilized into electrospinning nanofiber matrices (NMs) consisting of poly(vinyl alcohol) (PVA), chitosan (CHT), and poly-ε-caprolactone (PCL). Uniaxial nanofibers of PVA and PVA/CHT were developed, as well as coaxial nanofibers of PCL[PVA/CHT], in which the PCL works as a shell and the blend as a core. A crucial aspect of the present study is the in situ synthesis of AgNPs using PVA as a reducing and stabilizing agent. This process presents few steps, no additional toxic reducing agents, and avoids the postloading of drugs or the posttreatment of NM use. In general, the in situ synthesized AgNPs had an average size of 11.6 nm, and the incorporated nanofibers had a diameter in the range of 300 nm, with high uniformity and low polydispersity. The NM's spectroscopic, thermal, and mechanical properties were appropriate for the intended application. Uniaxial (PVA/AgNPs and PVA/CHT/AgNPs) and coaxial (PCL[PVA/CHT/AgNPs]) NMs presented virucidal activity (log's reduction ≥ 5) against mouse hepatitis virus (MHV-3) genus Betacoronavirus strains. In addition to that, the NMs did not present cytotoxicity against fibroblast cells (L929 ATCC® CCL-1TM lineage).

99mTc-AgNPs-ICG: nanoparticle for hybrid image / 99mTc-AgNPs-ICG: nanopartícula para imagem híbrida / 99mTc-AgNPs-ICG: nanopartícula para imagem híbrida

Introduction: Currently nanotechnology has radically changed the diagnosis of many human pathologies. The aim of this work is to obtain silver nanoparticles for hybrid imaging (99mTc-AgNPs-ICG) having potential clinical imaging applications. Materials and methods: We mixed 2 ml of ascorbic acid (1.7x10-4 M), 5 mCi of 99mTcO4- , 2 ml of citric acid (8.0x10-4 M) and 0.5 ml of silver nitrate (2.5x10-3 M). Solution pH was 5, and it was shaken for 20 minutes at 37º C. Afterwards, 2 µL of Indocyanine Green (1.3x10-3 M) was added (99mTc-AgNPs-ICG). Physiochemical properties of the solution were characterized by UV (λ1 = 420 nm, λ2 = 254 nm) and gamma detector. Fluorescence image, particle size and IR spectrum were evaluated. Results: Silver nanoparticles were obtained in aqueous solution a pH of 5. Their pH, color and spectrum were stable for seven days. Furthermore, the principal peak characterized by HPLC, UV and Gamma detector had similar retention times. Its UV spectrum showed an absorption band of 420 nm, which corresponds to the plasmon absorption band of these nanoparticles. The particle size was 46 nm ± 1.5 nm. The IR spectrum showed absorption bands in 3193, 2624, 1596 y 1212 cm-1. Conclusions: We describe for the first time in literature the synthesis of hybrid (radioactive and fluorescent) silver nanoparticles. Their physiochemical properties were characterized, being stable and their labelling was reproducible having potential biomedical applications.

Introducción: actualmente la nanotecnología ha cambiado radicalmente el diagnóstico de muchas patologías humanas. El objetivo de este trabajo es obtener nanopartículas de plata para imagen híbrida (99mTc-AgNPs-ICG) que tengan potenciales aplicaciones clínicas en imagen. Materiales y métodos: se mezclaron 2 ml de ácido ascórbico (1,7x10-4 M), 5 mCi de 99mTcO4- , 2 ml de ácido cítrico (8,0x10-4 M) y 0,5 ml de nitrato de plata (2,5x10-3 M). El pH de la solución fue 5, y se agitó durante 20 minutos a 37º C. A continuación, se añadieron 2 µl de verde de indocianina (1,3x10-3 M) (99mTc-AgNPs-ICG). Las propiedades fisicoquímicas de la solución se caracterizaron mediante UV (λ1 = 420 nm, λ2 = 254 nm) y detector gamma. Se evaluaron la imagen de fluorescencia, el tamaño de las partículas y el espectro IR. Resultados: se obtuvieron nanopartículas de plata en solución acuosa a un pH de 5. Su pH, color y espectro fueron estables durante siete días. Además, el pico principal caracterizado por HPLC, UV y detector Gamma tenía tiempos de retención similares. Su espectro UV mostró una banda de absorción de 420 nm, que corresponde a la banda de absorción plasmónica de estas nanopartículas. El tamaño de las partículas era de 46 nm ± 1,5 nm. El espectro IR mostró bandas de absorción en 3193, 2624, 1596 y 1212 cm-1. Conclusiones: describimos por primera vez en la literatura la síntesis de nanopartículas de plata híbridas (radioctivas y fluorescentes). Se caracterizaron sus propiedades fisicoquímicas, siendo estables y su etiquetado fue reproducible teniendo potenciales aplicaciones biomédicas.

Introdução: atualmente, a nanotecnologia mudou radicalmente o diagnóstico de muitas patologias humanas. O objetivo deste trabalho é obter nanopartículas de prata para imagens híbridas (99mTc-AgNPs-ICG) com possíveis aplicações de imagens clínicas. Materiais e métodos: misturamos 2 ml de ácido ascórbico (1,7x10-4 M), 5 mCi de 99mTcO4- , 2 ml de ácido cítrico (8,0x10-4 M) e 0,5 ml de nitrato de prata (2,5x10-3 M). O pH da solução era 5 e ela foi agitada por 20 minutos a 37º C. Em seguida, foram adicionados 2 µL de indocianina verde (1,3x10-3 M) (99mTc-AgNPs-ICG). As propriedades físico-químicas da solução foram caracterizadas por UV (λ1 = 420 nm, λ2 = 254 nm) e detector gama. A imagem de fluorescência, o tamanho das partículas e o espectro de infravermelho foram avaliados. Resultados: as nanopartículas de prata foram obtidas em solução aquosa com pH de 5. Seu pH, cor e espectro permaneceram estáveis por sete dias. Além disso, o pico principal caracterizado por HPLC, UV e detector gama teve tempos de retenção semelhantes. Seu espectro de UV mostrou uma banda de absorção de 420 nm, que corresponde à banda de absorção plasmônica dessas nanopartículas. O tamanho da partícula foi de 46 nm ± 1,5 nm. O espectro de IV mostrou bandas de absorção em 3193, 2624, 1596 e 1212 cm-1. Conclusões: descrevemos pela primeira vez na literatura a síntese de nanopartículas de prata híbridas (radioativas e fluorescentes). Suas propriedades físico-químicas foram caracterizadas, sendo estáveis e sua rotulagem foi reprodutível, com possíveis aplicações biomédicas.

99mTc-AgNPs-ICG: nanopartícula para imagen híbrida / 99mTc-AgNPs-ICG: nanoparticle for hybrid image / 99mTc-AgNPs-ICG: nanopartícula para imagem híbrida

Introducción: actualmente la nanotecnología ha cambiado radicalmente el diagnóstico de muchas patologías humanas. El objetivo de este trabajo es obtener nanopartículas de plata para imagen híbrida (99mTc-AgNPs-ICG) que tengan potenciales aplicaciones clínicas en imagen. Materiales y métodos: se mezclaron 2 ml de ácido ascórbico (1.7 x10-4 M), 5 mCi de 99mTcO4-, 2 ml de ácido cítrico (8.0 x 10-4 M) y 0.5 ml de nitrato de plata (2.5 x 10-3 M). El pH de la solución fue 5, y se agitó durante 20 minutos a 37º C. A continuación, se añadieron 2 µl de verde de indocianina (1.3 x 10-3 M) (99mTc-AgNPs-ICG). Las propiedades fisicoquímicas de la solución se caracterizaron mediante UV (λ1 = 420 nm, λ2 = 254 nm) y detector gamma. Se evaluaron la imagen de fluorescencia, el tamaño de las partículas y el espectro IR. Resultados: se obtuvieron nanopartículas de plata en solución acuosa a un pH de 5. Su pH, color y espectro fueron estables durante siete días. Además, el pico principal caracterizado por HPLC, UV y detector Gamma tenía tiempos de retención similares. Su espectro UV mostró una banda de absorción de 420 nm, que corresponde a la banda de absorción plasmónica de estas nanopartículas. El tamaño de las partículas era de 46 nm ± 1,5 nm. El espectro IR mostró bandas de absorción en 3193, 2624, 1596 y 1212 cm-1. Conclusiones: describimos por primera vez en la literatura la síntesis de nanopartículas de plata híbridas (radioactivas y fluorescentes). Se caracterizaron sus propiedades fisicoquímicas, siendo estables y su etiquetado fue reproducible teniendo potenciales aplicaciones biomédicas.

Introduction: Currently nanotechnology has radically changed the diagnosis of many human pathologies. The aim of this work is to obtain silver nanoparticles for hybrid imaging (99mTc-AgNPs-ICG) having potential clinical imaging applications. Materials and methods: We mixed 2 ml of ascorbic acid (1.7x10-4 M), 5 mCi of 99mTcO4-, 2 ml of citric acid (8.0 x 10-4 M) and 0.5 ml of silver nitrate (2.5 x 10-3 M). Solution pH was 5, and it was shaken for 20 minutes at 37º C. Afterwards, 2 µL of Indocyanine Green (1.3 x 10-3 M) was added (99mTc-AgNPs-ICG). Physiochemical properties of the solution were characterized by UV (λ1 = 420 nm, λ2 = 254 nm) and gamma detector. Fluorescence image, particle size and IR spectrum were evaluated. Results: Silver nanoparticles were obtained in aqueous solution a pH of 5. Their pH, color and spectrum were stable for seven days. Furthermore, the principal peak characterized by HPLC, UV and Gamma detector had similar retention times. Its UV spectrum showed an absorption band of 420 nm, which corresponds to the plasmon absorption band of these nanoparticles. The particle size was 46 nm ± 1.5 nm. The IR spectrum showed absorption bands in 3193, 2624, 1596 y 1212 cm-1. Conclusions: We describe for the first time in literature the synthesis of hybrid (radioactive and fluorescent) silver nanoparticles. Their physiochemical properties were characterized, being stable and their labelling was reproducible having potential biomedical applications.

Introdução: Atualmente, a nanotecnologia mudou radicalmente o diagnóstico de muitas patologias humanas. O objetivo deste trabalho é obter nanopartículas de prata para imagens híbridas (99mTc-AgNPs-ICG) com possíveis aplicações de imagens clínicas. Materiais e métodos: Misturamos 2 ml de ácido ascórbico (1.7 x 10-4 M), 5 mCi de 99mTcO4-, 2 ml de ácido cítrico (8.0 x 10-4 M) e 0.5 ml de nitrato de prata (2.5 x 10-3 M). O pH da solução era 5 e ela foi agitada por 20 minutos a 37º C. Em seguida, foram adicionados 2 µL de indocianina verde (1,3x10-3 M) (99mTc-AgNPs-ICG). As propriedades físico-químicas da solução foram caracterizadas por UV (λ1 = 420 nm, λ2 = 254 nm) e detector gama. A imagem de fluorescência, o tamanho das partículas e o espectro de infravermelho foram avaliados. Resultados: As nanopartículas de prata foram obtidas em solução aquosa com pH de 5. Seu pH, cor e espectro permaneceram estáveis por sete dias. Além disso, o pico principal caracterizado por HPLC, UV e detector gama teve tempos de retenção semelhantes. Seu espectro de UV mostrou uma banda de absorção de 420 nm, que corresponde à banda de absorção plasmônica dessas nanopartículas. O tamanho da partícula foi de 46 nm ± 1,5 nm. O espectro de IV mostrou bandas de absorção em 3193, 2624, 1596 e 1212 cm-1. Conclusões: Descrevemos pela primeira vez na literatura a síntese de nanopartículas de prata híbridas (radioativas e fluorescentes). Suas propriedades físico-químicas foram caracterizadas, sendo estáveis e sua rotulagem foi reprodutível, com possíveis aplicações biomédicas.

Stealth and biocompatible gold nanoparticles through surface coating with a zwitterionic derivative of glutathione

Gold nanoparticles (AuNPs) hold promise in biomedi-cine, but challenges like aggregation, protein corona formation, andinsufficient biocompatibility must be thoroughly addressed beforeadvancing their clinical applications. Designing AuNPs with specificprotein corona compositions is challenging, and strategies for coronaelimination, such as coating with polyethylene glycol (PEG), havelimitations. In this study, we introduce a commercially availablezwitterionic derivative of glutathione, glutathione monoethyl ester(GSHzwt), for the surface coating of colloidal AuNPs. Particles coatedwith GSHzwt were investigated alongside four other AuNPs coated withvarious ligands, including citrate ions, tiopronin, glutathione, cysteine,and PEG. We then undertook a head-to-head comparison of theseAuNPs to assess their behavior in biological fluid. GSHzwt-coated AuNPsexhibited exceptional resistance to aggregation and protein adsorption. The particles could also be readily functionalized with biotinand interact with streptavidin receptors in human plasma. Additionally, they exhibited significant blood compatibility andnoncytotoxicity. In conclusion, GSHzwt provides a practical and easy method for the surface passivation of AuNPs, creating “stealth”particles for potential clinical applications.

Antifungal Activity of Nontoxic Nanocomposite Based on Silver and Reduced Graphene Oxide against Dermatophytes and Candida spp.

Dermatomycoses are typical hair, skin, or nail infections caused mainly by dermatophytes and nondermatophytes: Trichophyton, Microsporum, Epidermophyton, and Candida. In addition to the esthetical impact, pain, and nail deformity, these mycoses can be a source of severe disease. The high cost of treatment, toxicity, and the emergence of resistant infectious agents justifies research into new drugs. This work evaluates the fungicidal activity of nanocomposites (NCs) based on reduced graphene oxide (rGO) loaded with silver (Ag) nanoparticles (rGO/Ag) against clinical isolates of dermatophytes and Candida species. This is an unprecedented study in which, for the first time, hybrid nanocompounds based on Ag/rGO were tested against Epidermophytom, Microsporum, and Trichophyton species (dermatophytes agents). In this paper, we synthesize rGO using different concentrations of Ag by hydrolysis of metal salt AgNO3 and follow the growth of nanocrystals on sheets of rGO provided by the NaBH4. The NCs were analyzed by X-ray diffraction analysis, and the NC morphology, silver distribution on the rGO surface, and crystalline information were investigated by transmission electron microscopy. Antifungal susceptibility assay was performed by the microdilution method based on modified Clinical and Laboratory Standards Institute (CLSI) protocol. Time-kill kinetics was conducted to monitor the effect of the composite to inhibit fungal cells or promote structural changes, avoiding germination. The toxicological evaluation of the NCs was born in an in vivo model based on Galleria mellonella (G. mellonella). Minimum inhibitory concentration (MIC) values of the rGO/Ag NCs ranged from 1.9 to 125 µg/mL. The best inhibitory activity was obtained for rGO/Ag12%, mainly against Candida spp. and Epidermophyton floccosum. In the presence of sorbitol, MIC values of rGO/Ag NCs were higher (ranging from 15.6 to 250 µg/mL), indicating the action mechanism on the cell wall. Both yeast and dermatophytes clinical isolates were inhibited at a minimum of 6 and 24 h, respectively, but after 2 and 12 h, they had initial antifungal interference. All hybrid formulations of rGO/Ag NCs were not toxic for G. mellonella. This study provides insights into an alternative therapeutic strategy for controlling dermatomycoses.

Bactericidal Activity of Silver Nanoparticles on Oral Biofilms Related to Patients with and without Periodontal Disease.

BACKGROUND AND OBJECTIVES: Periodontal disease (PD) is a multifactorial oral disease regularly caused by bacterial biofilms. Silver nanoparticles (AgNP) have offered good antimicrobial activity; moreover, there is no available scientific information related to their antimicrobial effects in biofilms from patients with PD. This study reports the bactericidal activity of AgNP against oral biofilms related to PD. MATERIALS AND METHODS: AgNP of two average particle sizes were prepared and characterized. Sixty biofilms were collected from patients with (30 subjects) and without PD (30 subjects). Minimal inhibitory concentrations of AgNP were calculated and the distribution of bacterial species was defined by polymerase chain reaction. RESULTS: Well-dispersed sizes of AgNP were obtained (5.4 ± 1.3 and 17.5 ± 3.4 nm) with an adequate electrical stability (-38.2 ± 5.8 and -32.6 ± 5.4 mV, respectively). AgNP showed antimicrobial activities for all oral samples; however, the smaller AgNP had significantly the most increased bactericidal effects (71.7 ± 39.1 µg/mL). The most resistant bacteria were found in biofilms from PD subjects (p < 0.05). P. gingivalis, T. denticola, and T. forsythia were present in all PD biofilms (100%). CONCLUSIONS: The AgNP showed efficient bactericidal properties as an alternative therapy for the control or progression of PD.

Chemical-analytical characterization and leaching of heavy metals associated with nanoparticles and microplastics from commercial face masks and the abundance of personal protective equipment (PPE) waste in three metropolitan cities of South America.

In this study, we surveyed the presence of personal protective equipment (PPE) waste on the streets of Bogotá-Colombia, Lima-Perú, and Mar del Plata-Argentina. Furthermore, this work is also focused on the release capacity of Ag, Cu, and Zn metals associated with nanoparticles, and microplastics (MPs) from textile face masks (TFMs) and disposable face masks. According to our results, an association between low-income areas and PPE waste was found, which may be related to the periodicity of waste collection and economic activity. Polymers, like polypropylene, cotton-polyester, and additives, such as CaCO3, MgO, and Ag/Cu as nanoparticles, were identified. TFMs released high levels of Cu (35,900-60,200 µg·L-1), Zn (2340-2380 µg·L-1), and MPs (4528-10,640 particles/piece). Metals associated with nanoparticles leached by face masks did not present any antimicrobial activity against P. aeruginosa. Our study suggests that TFMs may leach large amounts of polluting nano/micromaterials in aquatic environments with potential toxicological effects on organisms.

Dynamic Multi-Mode Mie Model for Gain-Assisted Metal Nano-Spheres.

Coupling externally pumped gain materials with plasmonic spherical particles, even in the simplest case of a single spherical nanoparticle in a uniform gain medium, generates an incredibly rich variety of electrodynamic phenomena. The appropriate theoretical description of these systems is dictated by the quantity of the included gain and the size of the nano-particle. On the one hand, when the gain level is below the threshold separating the absorption and the emission regime, a steady-state approach is a rather adequate depiction, yet a time dynamic approach becomes fundamental when this threshold is exceeded. On the other hand, while a quasi-static approximation can be used to model nanoparticles when they are much smaller than the exciting wavelength, a more complete scattering theory is necessary to discuss larger nanoparticles. In this paper, we describe a novel method including a time-dynamical approach to the Mie scattering theory, which is able to account for all the most enticing aspects of the problem without any limitation in the particle's size. Ultimately, although the presented approach does not fully describe the emission regime yet, it does allow us to predict the transient states preceding emission and represents an essential step forward in the direction of a model able to adequately describe the full electromagnetic phenomenology of these systems.

Metal Nanoparticles to Combat Candida albicans Infections: An Update.

Candidiasis is an opportunistic mycosis with high annual incidence worldwide. In these infections, Candida albicans is the chief pathogen owing to its multiple virulence factors. C. albicans infections are usually treated with azoles, polyenes and echinocandins. However, these antifungals may have limitations regarding toxicity, relapse of infections, high cost, and emergence of antifungal resistance. Thus, the development of nanocarrier systems, such as metal nanoparticles, has been widely investigated. Metal nanoparticles are particulate dispersions or solid particles 10-100 nm in size, with unique physical and chemical properties that make them useful in biomedical applications. In this review, we focus on the activity of silver, gold, and iron nanoparticles against C. albicans. We discuss the use of metal nanoparticles as delivery vehicles for antifungal drugs or natural compounds to increase their biocompatibility and effectiveness. Promisingly, most of these nanoparticles exhibit potential antifungal activity through multi-target mechanisms in C. albicans cells and biofilms, which can minimize the emergence of antifungal resistance. The cytotoxicity of metal nanoparticles is a concern, and adjustments in synthesis approaches or coating techniques have been addressed to overcome these limitations, with great emphasis on green synthesis.

Curcumin Mediated Gold Nanoparticles and Analysis of its Antioxidant, Anti-inflammatory, Antimicrobial Activity Against Oral Pathogens

ABSTRACT Objective: To green synthesise gold nanoparticles using curcumin and to analyse its antioxidant, anti-inflammatory, and antimicrobial activity among oral pathogens. Material and Methods: Biosynthesised Curcumin Gold nanoparticles (CuAuNP) were evaluated by UV-visible spectrophotometer (UV-Vis), Transmission Electron Microscopy (TEM), and evaluation of antioxidant, anti-inflammatory and antibacterial activity against oral pathogens. Results: Synthesized CuAuNP were characterized using UV-visible spectrophotometry and showed peak absorption at 530nm. CuAuNp showed a 90.3% maximum scavenging ability of DPPH at a concentration of 50 μg/mL. CuAuNP exhibited 79.6 % of the highest anti-inflammatory activity at 50μg/mL than the standard drug diclofenac. TEM image clearly showed uniformly dispersed spherical-shaped gold nanoparticles with a size of about 20 nm. The biosynthesized nanoparticle was tested for its antimicrobial effect, and it showed a potent effect against S. aureus, E. faecalis, and C. albicans at 100µg/ mL. Enterococcus faecalis has a maximum zone of inhibition of 14 mm at 100µg/ mL of CuAuNp. Among gram-positive bacteria, a maximum zone of inhibition of 12 mm at 100µg/ mL was seen in S. aureus compared to S mutans. Candida albicans showed a maximum zone of inhibition of 18 mm at 25 μg/mL of CuAuNp. Conclusion: Curcumin-mediated gold nanoparticles with 20 nm size were effective and had strong antioxidant and anti-inflammatory activity at 50µg/ mL, antimicrobial action inhibiting microbes at 100µg/mL concentration that can be used in treating various Oral mucosal lesions.

Electrochemical and Electroconductive Behavior of Silk Fibroin Electrospun Membrane Coated with Gold or Silver Nanoparticles.

The surface modification of materials obtained from natural polymers, such as silk fibroin with metal nanoparticles that exhibit intrinsic electrical characteristics, allows the obtaining of biocomposite materials capable of favoring the propagation and conduction of electrical impulses, acting as communicating structures in electrically isolated areas. On that basis, this investigation determined the electrochemical and electroconductive behavior through electrochemical impedance spectroscopy of a silk fibroin electrospun membrane from silk fibrous waste functionalized with gold or silver nanoparticles synthetized by green chemical reduction methodologies. Based on the results obtained, we found that silk fibroin from silk fibrous waste (SFw) favored the formation of gold (AuNPs-SFw) and silver (AgNPs-SFw) nanoparticles, acting as a reducing agent and surfactant, forming a micellar structure around the individual nanoparticle. Moreover, different electrospinning conditions influenced the morphological properties of the fibers, in the presence or absence of beads and the amount of sample collected. Furthermore, treated SFw electrospun membranes, functionalized with AuNPs-SFw or AgNPS-SFw, allowed the conduction of electrical stimuli, acting as stimulators and modulators of electric current.

Evaluation of collision/reaction gases in single-particle ICP-MS for sizing selenium nanoparticles and assessment of their antibacterial activity.

Selenium nanoparticles (SeNPs) have recently attracted attention because they combine the benefits of Se and lower toxicity compared to other chemical forms of this element. In this study, SeNPs were synthesized by a green method using ascorbic acid as the reducing agent and polyvinyl alcohol as stabilizer. The nanoparticles were widely characterized. To determine the total concentration of Se by ICP-MS, several isotopes and the use of He as collision gas were evaluated, which was effective in minimizing interferences. A method for sizing SeNPs by single particle ICP-MS (SP-ICP-MS) was developed. For this purpose, He and H2were evaluated as collision/reaction gases, and the second one showed promising results, providing an average diameter of 48 nm for the SeNPs. These results agree with those obtained by TEM (50.1 nm). Therefore, the SP-ICP-MS can be implemented for characterizing SeNPs in terms of size and size distribution, being an important analytical tool for Se and other widely studied nanoparticles (e.g. Ag, Au, Ce, Cu, Fe, Zn). Finally, the antibacterial activity of SeNPs was assessed. The SeNPs showed bacteriostatic activity against three strains of Gram-positive bacteria and were particularly efficient in inhibiting the growthE. faecaliseven at very low concentrations (MIC < 1.4 mg l-1). In addition, a bactericidal activity of SeNPs againstS. aureuswas observed. These nanoparticles may have potential application in pharmaceutical industry, biomedicine and agriculture.

Green Synthesis of Gold and Silver Nanoparticles Using Leaf Extract of Capsicum chinense Plant.

So far, several studies have focused on the synthesis of metallic nanoparticles making use of extracts from the fruit of the plants from the genus Capsicum. However, as the fruit is the edible, and highly commercial, part of the plant, in this work we focused on the leaves, a part of the plant that is considered agro-industrial waste. The biological synthesis of gold (AuNPs) and silver (AgNPs) nanoparticles using aqueous extracts of root, stem and leaf of Capsicum chinense was evaluated, obtaining the best results with the leaf extract. Gold and silver nanoparticles synthesized using leaf extract (AuNPs-leaf and AgNPs-leaf, respectively) were characterized by UV-visible spectrophotometry (UV-Vis), Fourier Transform Infrared Spectroscopy with Attenuated Total Reflection (FTIR-ATR), X-ray Photoelectron Spectroscopy (XPS), Ultra Hight Resolution Scanning Electron Microscopy coupled to Energy-Dispersive X-ray spectroscopy (UHR-SEM-EDX) and Transmission Electron Microscopy (TEM), and tested for their antioxidant and antimicrobial activities. In addition, different metabolites involved in the synthesis of nanoparticles were analyzed. We found that by the use of extracts derived from the leaf, we could generate stable and easy to synthesize AuNPs and AgNPs. The AuNPs-leaf were synthesized using microwave radiation, while the AgNPs-leaf were synthesized using UV light radiation. The antioxidant activity of the extract, determined by ABTS, showed a decrease of 44.7% and 60.7% after the synthesis of the AuNPs-leaf and AgNPs-leaf, respectively. After the AgNPs-leaf synthesis, the concentration of polyphenols, reducing sugars and amino acids decreased by 15.4%, 38.7% and 46.8% in the leaf extract, respectively, while after the AuNPs-leaf synthesis only reducing sugars decreased by 67.7%. These results suggest that these groups of molecules are implicated in the reduction/stabilization of the nanoparticles. Although the contribution of these compounds in the synthesis of the AuNPs-leaf and the AgNPs-leaf was different. Finally, the AgNPs-leaf inhibited the growth of S. aureus, E. coli, S. marcescens and E. faecalis. All of them are bacterial strains of clinical importance due to their fast antibiotic resistance development.

Synthesis, Characterization, Applications, and Toxicity of Green Synthesized Nanoparticles.

Nanotechnology is a cutting-edge area with numerous industrial applications. Nanoparticles are structures that have dimensions ranging from 1 - 100 nm, which significantly exhibit different mechanical, optical, electrical, and chemical properties when compared with their larger counterparts. Synthetic routes that use natural sources, such as plant extracts, honey, and microorganisms, are environmentally friendly and low-cost methods that can be used to obtain nanoparticles. These methods of synthesis generate products that are more stable and less toxic than those obtained using conventional methods. Nanoparticles formed by titanium dioxide, zinc oxide, silver, gold, and copper, as well as cellulose nanocrystals, are among the nanostructures obtained by green synthesis that have shown interesting applications in several technological industries. Several analytical techniques have also been used to analyze the size, morphology, hydrodynamics, diameter, and chemical functional groups involved in the stabilization of the nanoparticles as well as to quantify and evaluate their formation. Despite their pharmaceutical, biotechnological, cosmetic, and food applications, studies have detected their harmful effects on human health and the environment, and thus, caution must be taken in uses involving living organisms. The present review aims to present an overview of the applications, the structural properties, and the green synthesis methods that are used to obtain nanoparticles, and special attention is given to those obtained from metal ions. The review also presents the analytical methods used to analyze, quantify, and characterize these nanostructures.

Metal nanoparticles produced by plants with antibacterial properties against Staphylococcus aureus / Nanopartículas metálicas produzidas por plantas com propriedades antibacterianas contra Staphylococcus aureus

Staphylococcus aureus (S. aureus) is a pathogenic bacteria that causes a variety of potentially fatal infections. The emergence of antibiotic-resistant strains of S. aureus has made treatment even more difficult. In recent years, nanoparticles have been used as an alternative therapeutic agent for S. aureus infections. Among various methods for the synthesis of nanoparticles, the method utilizing plant extracts from different parts of a plant, such as root, stem, leaf, flower, seeds, etc. is gaining widespread usage. Phytochemicals present in plant extract are an inexpensive, eco-friendly, natural material that act as reducing and stabilization agent for the nanoparticle synthesis. The utilization of plant-fabricated nanoparticles against S. aureus is currently in trend. The current review discusses recent findings in the therapeutic application of phytofabricated metal-based nanoparticles against Staphylococcus aureus.

Staphylococcus aureus (S. aureus) é uma bactéria patogênica que causa uma variedade de infecções potencialmente fatais. O surgimento de cepas de S. aureus resistentes a antibióticos tornou o tratamento ainda mais difícil. Nos últimos anos, as nanopartículas têm sido utilizadas como um agente terapêutico alternativo para infecções por S. aureus. Entre os diversos métodos para a síntese de nanopartículas, o que utiliza extratos vegetais de diferentes partes de uma planta, como raiz, caule, folha, flor, sementes etc., vem se destacando a partir do uso generalizado. Os fitoquímicos presentes no extrato vegetal são um material natural de baixo preço e ecologicamente correto que atuam como agente redutor e estabilizador para a síntese de nanopartículas. A utilização de nanopartículas fabricadas em plantas contra S. aureus é uma tendência atualmente. Nesse sentido, presente trabalho discute achados recentes na aplicação terapêutica de nanopartículas à base de metal fitofabricadas contra Staphylococcus aureus.

Evaluation of antibacterial properties and shear bond strength of orthodontic composites containing silver nanoparticles, titanium dioxide nanoparticles and fluoride: An in vitro study

ABSTRACT Objective: The study aimed at determining the antibacterial properties of composites containing silver nanoparticles (Ag NPs) or titanium dioxide nanoparticles (TiO2 NPs), and a fluoride-releasing composite against Streptococcus mutans and Lactobacillus acidophilus, and to evaluate the effect on shear bond strength (SBS) of nanoparticles-modified composites. Materials and Methods: An orthodontic composite was modified by adding 1% w/w Ag NPs or 1% w/w TiO2 NPs. Composite discs were prepared to evaluate the antibacterial properties of these modified composites against Streptococcus mutans and Lactobacillus acidophilus, using three different antibacterial tests, namely: Disk agar diffusion test, Biofilm inhibition test and eluted component test. For evaluating the shear bond strength, 80 extracted premolars were collected and divided into four groups (n=20 each), which were bonded with stainless steel preadjusted Edgewise brackets, by using these modified composites. Their SBS was then compared with that of the control group, using a universal testing machine. Results: Composite discs containing nanoparticles and fluoride were capable of producing growth inhibition zones for all bacterial types. Results of the biofilm inhibition test showed that all the study groups inhibited the bacterial count, in comparison to the control group. A significant difference of SBS was observed between all groups. Conclusion: The antibacterial activity of orthodontic composites modified with Ag and TiO2 nanoparticles was significant, compared with conventional and fluoride-containing composites. The control group showed the highest SBS, followed by fluoride, titanium, and silver groups, with statistically significant difference in mean SBS values among all groups.

RESUMO Objetivo: O objetivo do presente estudo foi determinar a eficácia das propriedades antibacterianas de compósitos contendo nanopartículas de prata (Ag NPs) ou nanopartículas de dióxido de titânio (TiO2 NPs) e de um compósito com liberação de flúor, contra as bactérias Streptococcus mutans e Lactobacillus acidophilus e, também, avaliar o efeito na resistência ao cisalhamento (RC) desses compósitos modificados com nanopartículas. Métodos: Os compósitos ortodônticos foram modificados pela adição de 1% p/p de Ag NPs e 1% p/p de TiO2 NPs. Discos de compósito foram preparados para avaliar as propriedades antibacterianas desses grupos contra as bactérias Streptococcus mutans e Lactobacillus acidophilus, usando três testes antibacterianos diferentes: teste de disco-difusão em ágar, teste de inibição da formação de biofilme e teste de componentes eluídos. Para avaliar a resistência ao cisalhamento dos compósitos, 80 pré-molares extraídos foram coletados e divididos em quatro grupos, contendo 20 dentes cada. Foram utilizados braquetes Edgewise pré-ajustados de aço inoxidável para colagem nos dentes usando as resinas modificadas. A RC desses compósitos modificados foi comparada à dos grupos controle, usando uma máquina universal de testes. Resultados: Os discos de compósito contendo as nanopartículas e flúor foram capazes de produzir halos de inibição de crescimento para todos os tipos de bactérias. Os resultados do teste de inibição do biofilme mostraram que houve uma redução na contagem de bactérias em relação ao grupo controle. Diferenças significativas na RC foram observadas entre todos os grupos. Conclusão: A atividade antibacteriana dos compósitos ortodônticos modificados com nanopartículas de Ag e TiO2 foi significativa, quando comparada ao compósito convencional e ao compósito com flúor. O grupo controle apresentou a maior RC, seguido pelos grupos Flúor, Titânio e Prata, com diferença estatisticamente significativa nos valores médios da RC entre todos os grupos.

Raman spectroscopy and silver nanoparticles for efficient detection of membrane proteins in living cells.

Molecular fingerprints revealed by Raman techniques show great potential for biomedical applications, like disease diagnostic through Raman detection of tumor markers and other molecules in the cell membrane. However, SERS substrates used in membrane molecule studies produce enhanced Raman spectra of high variability and challenging band assignments that limit their application. In this work, these drawbacks are addressed to detect membrane-associated hemoglobin (Hbm) in human erythrocytes through Raman spectroscopy. These cells are incubated with silver nanoparticles (AgNPs) in PBS before Raman measurements. Our results showed that AgNPs form large aggregates in PBS that adhered to the erythrocyte membrane, which enhances Raman scattering by molecules around the membrane, like Hbm. Also, deoxyHb markers may allow Hbmdetection in Raman spectra of oxygenated erythrocytes (oxyRBCs). Raman spectra of oxyRBCs incubated with AgNPs showed enhanced deoxyHb signals with good spectral reproducibility, supporting the Hbmdetection through deoxyHb markers. Instead, Raman spectra of oxyRBCs showed oxyHb bands associated with free cytoplasmic hemoglobin. Other factors influencing Raman detection of membrane proteins are discussed, like bothz-position and dimension of the sample volume. The results encourage membrane protein studies in living cells using Raman spectroscopy, leading to the characterization and diagnostic of different pathologies through a non-invasive technique.