Synergistic antimicrobial photodynamic therapy using gated mesoporous silica nanoparticles containing curcumin and polymyxin B.

Photodynamic Therapy is a therapy based on combining a non-toxic compound, known as photosensitizer (PS), and irradiation with light of the appropriate wavelength to excite the PS molecule. The photon absorption by the PS leads to reactive oxygen species generation and a subsequent oxidative burst that causes cell damage and death. In this work, we report an antimicrobial nanodevice that uses the activity of curcumin (Cur) as a PS for antimicrobial Photodynamic Therapy (aPDT), based on mesoporous silica nanoparticles in which the action of the classical antibiotic PMB is synergistically combined with the aPDT properties of curcumin to combat bacteria. The synergistic effect of the designed gated device in combination with irradiation with blue LED light (470 nm) is evaluated against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus epidermidis. The results show that the nanodevice exhibits a noteworthy antibacterial activity against these microorganisms, a much more significant effect than free Cur and PMB at equivalent concentrations. Thus, 0.1 µg/mL of MSNs-Cur-PMB eliminates a bacterial concentration of about 105 CFU/mL of E. coli, while 1 µg/mL of MSNs-Cur-PMB is required for P. aeruginosa and S. epidermidis. In addition, antibiofilm activity against the selected bacteria was also tested. We found that 0.1 mg/mL of MSNs-Cur-PMB inhibited 99 % biofilm formation for E. coli, and 1 mg/mL of MSNs-Cur-PMB achieved 90 % and 100 % inhibition of biofilm formation for S. epidermidis and P. aeruginosa, respectively.

Exploring the Synergy between Nano-Formulated Linezolid and Polymyxin B as a Gram-Negative Effective Antibiotic Delivery System Based on Mesoporous Silica Nanoparticles.

Antimicrobial resistance is a current silent pandemic that needs new types of antimicrobial agents different from the classic antibiotics that are known to lose efficiency over time. Encapsulation of antibiotics inside nano-delivery systems could be a promising, effective strategy that is able to delay the capability of pathogens to develop resistance mechanisms against antimicrobials. These systems can be adapted to deliver already discovered antibiotics to specific infection sites in a more successful way. Herein, mesoporous silica nanomaterials are used for an efficient delivery of a linezolid gram-positive antibiotic that acts synergistically with gram-negative antimicrobial polymyxin B. For this purpose, linezolid is encapsulated in the pores of the mesoporous silica, whose outer surface is coated with a polymyxin B membrane disruptor. The nanomaterial showed a good controlled-release performance in the presence of lipopolysaccharide, found in bacteria cell membranes, and the complete bacteria E. coli DH5α. The performed studies demonstrate that when the novel formulation is near bacteria, polymyxin B interacts with the cell membrane, thereby promoting its permeation. After this step, linezolid can easily penetrate the bacteria and act with efficacy to kill the microorganism. The nano-delivery system presents a highly increased antimicrobial efficacy against gram-negative bacteria, where the use of free linezolid is not effective, with a fractional inhibitory concentration index of 0.0063 for E. coli. Moreover, enhanced toxicity against gram-positive bacteria was confirmed thanks to the combination of both antibiotics in the same nanoparticles. Although this new nanomaterial should be further studied to reach clinical practice, the obtained results pave the way to the development of new nanoformulations which could help in the fight against bacterial infections.

Toxicological Profiling and Long-Term Effects of Bare, PEGylated- and Galacto-Oligosaccharide-Functionalized Mesoporous Silica Nanoparticles.

Mesoporous silica nanoparticles (MSNs) are amongst the most used nanoparticles in biomedicine. However, the potentially toxic effects of MSNs have not yet been fully evaluated, being a controversial matter in research. In this study, bare MSNs, PEGylated MSNs (MSNs-PEG), and galacto-oligosaccharide-functionalized MSNs (MSNs-GAL) are synthesized and characterized to assess their genotoxicity and transforming ability on human lung epithelial BEAS-2B cells in short- (48 h) and long-term (8 weeks) exposure scenarios. Initial short-term treatments show a dose-dependent increase in genotoxicity for MSNs-PEG-treated cells but not oxidative DNA damage for MSNs, MSNs-PEG, or for MSNs-GAL. In addition, after 8 weeks of continuous exposure, neither induced genotoxic nor oxidative DNA is observed. Nevertheless, long-term treatment with MSNs-PEG and MSNs-GAL, but not bare MSNs, induces cell transformation features, as evidenced by the cell's enhanced ability to grow independently of anchorage, to migrate, and to invade. Further, the secretome from cells treated with MSNs and MSNs-GAL, but not MSNs-PEG, shows certain tumor-promoting abilities, increasing the number and size of HeLa cell colonies formed in the indirect soft-agar assay. These results show that MSNs, specifically the functionalized ones, provoke some measurable adverse effects linked to tumorigenesis. These effects are in the order of other nanomaterials, such as carbon nanotubes or cerium dioxide nanoparticles, but they are lower than those provoked by some approved drugs, such as doxorubicin or dexamethasone.

Development of Photonic Multi-Sensing Systems Based on Molecular Gates Biorecognition and Plasmonic Sensors: The PHOTONGATE Project.

This paper presents the concept of a novel adaptable sensing solution currently being developed under the EU Commission-founded PHOTONGATE project. This concept will allow for the quantification of multiple analytes of the same or different nature (chemicals, metals, bacteria, etc.) in a single test with levels of sensitivity and selectivity at/or over those offered by current solutions. PHOTONGATE relies on two core technologies: a biochemical technology (molecular gates), which will confer the specificity and, therefore, the capability to be adaptable to the analyte of interest, and which, combined with porous substrates, will increase the sensitivity, and a photonic technology based on localized surface plasmonic resonance (LSPR) structures that serve as transducers for light interaction. Both technologies are in the micron range, facilitating the integration of multiple sensors within a small area (mm2). The concept will be developed for its application in health diagnosis and food safety sectors. It is thought of as an easy-to-use modular concept, which will consist of the sensing module, mainly of a microfluidics cartridge that will house the photonic sensor, and a platform for fluidic handling, optical interrogation, and signal processing. The platform will include a new optical concept, which is fully European Union Made, avoiding optical fibers and expensive optical components.

Human Papilloma Virus DNA Detection in Clinical Samples Using Fluorogenic Probes Based on Oligonucleotide Gated Nanoporous Anodic Alumina Films.

In this work, fluorogenic probes based on oligonucleotide capped nanoporous anodic alumina films are developed for specific and sensitive detection of human papilloma virus (HPV) DNA. The probe consists of anodic alumina nanoporous films loaded with the fluorophore rhodamine B (RhB) and capped with oligonucleotides bearing specific base sequences complementary to genetic material of different high-risk (hr) HPV types. Synthesis protocol is optimized for scale up production of sensors with high reproducibility. The sensors' surfaces are characterized by scanning electron microscopy (HR-FESEM) and atomic force microscopy (AFM) and their atomic composition is determined by energy dispersive X-ray spectroscopy (EDXS). Oligonucleotide molecules onto nanoporous films block the pores and avoid diffusion of RhB to the liquid phase. Pore opening is produced when specific DNA of HPV is present in the medium, resulting in RhB delivery, that is detected by fluorescence measurements. The sensing assay is optimized for reliable fluorescence signal reading. Nine different sensors are synthesized for specific detection of 14 different hr-HPV types in clinical samples with very high sensitivity (100%) and high selectivity (93-100%), allowing rapid screening of virus infections with very high negative predictive values (100%).

Diagnóstico prenatal de dos casos de anomalías congénitas del desarrollo venoso sistémico: una entidad muy poco frecuente (España) / Prenatal diagnosis of two cases of congenital systemic venus return anomalies: a rare entity (Spain) / Diagnóstico pré-natal de dois casos de anormalidades congênitas do desenvolvimento venoso sistêmico: uma entidade muito rara (Espanha)

Introducción: las anomalías en el desarrollo del sistema venoso sistémico son una entidad poco frecuente, cuyo diagnóstico ecocardiográfico prenatal y posnatal puede suponer todo un reto. Por un lado, debido a su baja incidencia y por otro, a la dificultad en la correcta realización de los planos ecocardiográficos. No obstante, su diagnóstico es de vital importancia debido a la asociación con cardiopatías congénitas o cromosopatías. Objetivo: describir dos casos de una anomalía congénita cardiovascular poco frecuente. La persistencia de la vena cava superior izquierda con agenesia de la vena cava superior derecha es una de estas anomalías descritas cuya incidencia es muy baja cuando ambas variaciones se presentan conjuntamente. Casos clínicos: presentamos dos casos de recién nacidos sin antecedentes personales o familiares de interés, diagnosticados prenatalmente, cuyos hallazgos ecocardiográficos se confirman en el período posnatal. Conclusiones: ante el hallazgo aislado en el período fetal de esta variación anatómica que asocia dos anomalías del sistema venoso sistémico, cabe destacar la importancia de su confirmación ecocardiográfica posnatal para descartar cardiopatías congénitas de difícil diagnóstico durante la época prenatal. Así mismo, antes de la confirmación ecocardiográfica que será llevada a cabo por el cardiológico infantil, cabe destacar la importancia del pediatra en la primera exploración física y en la anamnesis a la familia para descartar posibles cardiopatías congénitas críticas o posibles síndromes asociados. El diagnóstico prenatal de persistencia de la vena cava superior izquierda con agenesia de la vena cava superior derecha le permitirá tener un alto grado de sospecha de estas patologías asociadas y por tanto llevar a cabo una actuación clínica precoz.

Introduction: anomalies in the development of the systemic venous system are a rare entity, and its prenatal and postnatal echocardiographic diagnosis can be challenging, due to its low incidence as well as to the difficulty in correctly performing echocardiographic imaging planes. However, its diagnosis is key because it is linked to congenital heart disease or chromosomal anomalies. Objective: describe two cases of a rare cardiovascular congenital anomaly. The persistence of the left superior vena cava with agenesis of the right superior vena cava is one of these described anomalies, with very low incidence when both variations occur together. Clinical cases: we present two cases of newborns with no relevant personal or family history, diagnosed prenatally with confirmed echocardiographic findings in the postnatal period. Conclusions: given the isolated finding in the fetal period of this anatomical variation that associates two anomalies of the systemic venous system, we should note the importance of its postnatal echocardiographic confirmation to rule out congenital heart disease that is difficult to diagnose during the prenatal period. Likewise, prior to the echocardiographic confirmation carried out by the pediatric cardiologist, we should stress the importance of the pediatrician diagnosis in the first physical examination and of the family history to rule out possible critical congenital heart disease or possible associated syndromes. The prenatal diagnosis of VCSIP with agenesis of the VCSD will lead to a high degree of suspicion of these associated pathologies and therefore may lead to early clinical action.

Introdução: as anomalias no desenvolvimento do sistema venoso sistêmico são uma entidade rara, cujo diagnóstico ecocardiográfico pré-natal e pós-natal pode ser um grande desafio. Por um lado, pela sua baixa incidência e, por outro, pela dificuldade em realizar corretamente os planos ecocardiográficos. No entanto, seu diagnóstico é vital devido à associação com cardiopatias congênitas ou anormalidades cromossômicas. Objetivo: descrever dois casos de rara anomalia congênita cardiovascular. A persistência da veia cava superior esquerda com agenesia da veia cava superior direita é uma dessas anomalias descritas cuja incidência é muito baixa quando ambas as variações ocorrem juntas. Casos clínicos: apresentamos dois casos de recém-nascidos sem antecedentes pessoais ou familiares significativos, diagnosticados no pré-natal e cujos achados ecocardiográficos foram confirmados no período pós-natal. Conclusões: dado o achado isolado no período fetal desta variação anatômica que associa duas anomalias do sistema venoso sistêmico, devemos ressaltar a importância de sua confirmação ecocardiográfica pós-natal para descartar cardiopatia congênita de difícil diagnóstico no pré-natal . Da mesma forma, antes da confirmação ecocardiográfica que será realizada pelo cardiologista pediátrico, ressaltamos a importância do pediatra no primeiro exame físico e na história familiar para afastar possíveis cardiopatias congênitas críticas ou possíveis síndromes associadas. O diagnóstico pré-natal de VCSIP com agenesia do VCSD permitirá ter um alto grau de suspeita dessas patologias associadas e, portanto, realizar uma ação clínica precoce.

Gated Organonanoclays for Large Biomolecules: Controlled Release Triggered by Surfactant Stimulus.

The low toxicity and high adsorption capacities of clay minerals make them attractive for controlled delivery applications. However, the number of controlled-release studies in the literature using clay minerals is still scarce. In this work, three different clays from the smectite group (Kunipia F, montmorillonite; Sumecton SA, saponite; and Sumecton SWN, hectorite) were successfully loaded with rhodamine B dye and functionalized with oleic acid as a gatekeeper to produce organonanoclays for active and controlled payload-release. Moreover, hematin and cyanocobalamin have also been encapsulated in hectorite gated clay. These organonanoclays were able to confine the entrapped cargos in an aqueous environment, and effectively release them in the presence of surfactants (as bile salts). A controlled delivery of 49 ± 6 µg hematin/mg solid and 32.7 ± 1.5 µg cyanocobalamin/mg solid was reached. The cargo release profiles of all of the organonanoclays were adjusted to three different release-kinetic models, demonstrating the Korsmeyer-Peppas model with release dependence on (i) the organic-inorganic hybrid system, and (ii) the nature of loaded molecules and their interaction with the support. Furthermore, in vitro cell viability assays were carried out with Caco-2 cells, demonstrating that the organonanoclays are well tolerated by cells at particle concentrations of ca. 50 µg/mL.

[Use of abdominal X-ray in drug intoxication: a pediatric case report]. / Utilidad de la radiografía de abdomen en el diagnóstico de la intoxicación medicamentosa: reporte de un caso pediátrico.

Drug intoxication is a common reason for pediatric emergency department (ED) visits and one of the leading causes of death among teenagers. Early diagnosis and treatment are essential for a proper management of these patients. We present a 13-year-old girl attended at the ED showing excessive sleepiness and gastrointestinal symptoms after taking an unknown drug. Due to suspected iron overdose and the impossibility of measuring urgent iron levels, an abdominal X-ray was performed, which confirmed the diagnosis. We highlight the utility of radiology in the diagnosis of iron poisoning, which is possible due to its radiopacity.

Las intoxicaciones medicamentosas son un motivo de consulta frecuente en pediatría, además de una de las principales causas externas de mortalidad en adolescentes. El diagnóstico y tratamiento tempranos son fundamentales para el manejo adecuado de estos casos. Se presenta una niña de 13 años que, luego de ingerir un fármaco desconocido, muestra decaimiento y manifestaciones clínicas gastrointestinales. Por sospecha de intoxicación con hierro y la imposibilidad de determinar los niveles de sideremia de manera urgente, se realiza radiografía de abdomen, que confirma el diagnóstico y permite el tratamiento adecuado de la paciente. En este caso, se destaca la utilidad de la radiología para el diagnóstico en la sospecha de intoxicación con hierro, gracias a la radiopacidad de sus sales.

Fluorogenic Detection of Human Serum Albumin Using Curcumin-Capped Mesoporous Silica Nanoparticles.

Mesoporous silica nanoparticles loaded with rhodamine B and capped with curcumin are used for the selective and sensitive fluorogenic detection of human serum albumin (HSA). The sensing mesoporous silica nanoparticles are loaded with rhodamine B, decorated with aminopropyl moieties and capped with curcumin. The nanoparticles selectively release the rhodamine B cargo in the presence of HSA. A limit of detection for HSA of 0.1 mg/mL in PBS (pH 7.4)-acetonitrile 95:5 v/v was found, and the sensing nanoparticles were used to detect HSA in spiked synthetic urine samples.

Aerogels as promising materials for antibacterial applications: a mini-review.

The increasing cases of bacterial infections originating from resistant bacteria are a serious problem globally and many approaches have been developed for different purposes to treat bacterial infections. Aerogels are a novel class of smart porous materials composed of three-dimensional networks. Recently, aerogels with the advantages of ultra-low density, high porosity, tunable particle and pore sizes, and biocompatibility have been regarded as promising carriers for the design of delivery systems. Recently, aerogels have also been provided with antibacterial activity through loading of antibacterial agents, incorporation of metal/metal oxides and via surface functionalization and coating with various functional groups. In this mini-review, the synthesis of aerogels from both conventional and low-cost precursors is reported and examples of aerogels displaying antibacterial properties are summarized. As a result, it is clear that the encouraging antibacterial performance of aerogels promotes their use in many antibacterial applications, especially in the food industry, pharmaceutics and medicine.

Lactose-Gated Mesoporous Silica Particles for Intestinal Controlled Delivery of Essential Oil Components: An In Vitro and In Vivo Study.

Mesoporous silica microparticles functionalized with lactose for the specific release of essential oil components (EOCs) in the small intestine are presented. In vitro and in vivo intestinal models were applied to validate the microparticles (M41-EOC-L), in which the presence of lactase acts as the triggering stimulus for the controlled release of EOCs. Among the different microdevices prepared (containing thymol, eugenol and cinnamaldehyde), the one loaded with cinnamaldehyde showed the most significant Caco-2 cell viability reduction. On the other hand, interaction of the particles with enterocyte-like monolayers showed a reduction of EOCs permeability when protected into the designed microdevices. Then, a microdevice loaded with cinnamaldehyde was applied in the in vivo model of Wistar rat. The results showed a reduction in cinnamaldehyde plasma levels and an increase in its concentration in the lumen of the gastrointestinal tract (GIT). The absence of payload release in the stomach, the progressive release throughout the intestine and the prolonged stay of the payload in the GIT-lumen increased the bioavailability of the encapsulated compound at the site of the desired action. These innovative results, based on the specific intestinal controlled delivery, suggest that the M41-payload-L could be a potential hybrid microdevice for the protection and administration of bioactive molecules in the small intestine and colon.

Gene-Directed Enzyme Prodrug Therapy by Dendrimer-Like Mesoporous Silica Nanoparticles against Tumor Cells.

We report herein a gene-directed enzyme prodrug therapy (GDEPT) system using gated mesoporous silica nanoparticles (MSNs) in an attempt to combine the reduction of side effects characteristic of GDEPT with improved pharmacokinetics promoted by gated MSNs. The system consists of the transfection of cancer cells with a plasmid controlled by the cytomegalovirus promoter, which promotes ß-galactosidase (ß-gal) expression from the bacterial gene lacZ (CMV-lacZ). Moreover, dendrimer-like mesoporous silica nanoparticles (DMSNs) are loaded with the prodrug doxorubicin modified with a galactose unit through a self-immolative group (DOXO-Gal) and modified with a disulfide-containing polyethyleneglycol gatekeeper. Once in tumor cells, the reducing environment induces disulfide bond rupture in the gatekeeper with the subsequent DOXO-Gal delivery, which is enzymatically converted by ß-gal into the cytotoxic doxorubicin drug, causing cell death. The combined treatment of the pair enzyme/DMSNs-prodrug are more effective in killing cells than the free prodrug DOXO-Gal alone in cells transfected with ß-gal.

A new 8-oxo-7,8-2'deoxyguanosine nanoporous anodic alumina aptasensor for colorectal cancer diagnosis in blood and urine.

Many important human diseases, and especially cancer, have been related to the overproduction of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG). This molecule is a product of oxidative stress processes over nucleophilic bases in DNA. In this work, an aptasensor for the rapid, selective and accurate detection of this oncomarker is presented. The aptasensor consists of a nanoporous anodic alumina material loaded with a dye and is functionalized with an aptamer-based "molecular gate". In the presence of target 8-oxo-dG, the capping aptamer displaces from the surface due to the high affinity of the analyte with the capping aptamer, thus inducing delivery of the preloaded fluorescent dye. In contrast, in the absence of 8-oxo-dG, a poor payload delivery is accomplished. This aptamer-based nanodevice has great sensitivity for 8-oxo-dG, resulting in a LOD of 1 nM and a detection time of ca. 60 min. Moreover, the aptasensor is able to accurately detect 8-oxo-dG in unmodified urine and serum without pre-concentration treatments. This diagnostic tool is validated in a set of 38 urine and serum samples from patients diagnosed of colorectal cancer and control patients. These samples are also analyzed using a standardized and specific ELISA kit. The aptasensor displays excellent sensitivity (95.83/100%) and specificity (80/100%) for 8-oxo-dG detection in serum and urine samples, respectively. Our results may serve as a basis for the development of generalized fluorogenic diagnostic platforms for the easy diagnosis of cancer in biofluids as well as for monitoring therapeutic treatments and detection of relapses without the use of expensive equipment or trained personnel.

Towards the Enhancement of Essential Oil Components' Antimicrobial Activity Using New Zein Protein-Gated Mesoporous Silica Microdevices.

The development of new food preservatives is essential to prevent foodborne outbreaks or food spoilage due to microbial growth, enzymatic activity or oxidation. Furthermore, new compounds that substitute the commonly used synthetic food preservatives are needed to stifle the rising problem of microbial resistance. In this scenario, we report herein, as far as we know, for the first time the use of the zein protein as a gating moiety and its application for the controlled release of essential oil components (EOCs). The design of microdevices consist of mesoporous silica particles loaded with essential oils components (thymol, carvacrol and cinnamaldehyde) and functionalized with the zein (prolamin) protein found in corn as a molecular gate. The zein protein grafted on the synthesized microdevices is degraded by the proteolytic action of bacterial enzymatic secretions with the consequent release of the loaded essential oil components efficiently inhibiting bacterial growth. The results allow us to conclude that the new microdevice presented here loaded with the essential oil component cinnamaldehyde improved the antimicrobial properties of the free compound by decreasing volatility and increasing local concentration.

A fluorogenic capped mesoporous aptasensor for gluten detection.

Celiac disease is a complex and autoimmune disorder caused by the ingestion of gluten affecting almost 1% of global population. Nowadays an effective treatment does not exist, and the only way to manage the disease is the removal of gluten from the diet. Owing the key role played by gluten, clear and regulated labelling of foodstuff and smart methods for gluten detection are needed to fight frauds on food industry and to avoid the involuntary ingestion of this protein by celiac patients. On that scope, the development of a novel detection system of gluten is here presented. The sensor consists of nanoporous anodic alumina films loaded with a fluorescent dye and capped with an aptamer that recognizes gliadin (gluten's soluble proteins). In the presence of gliadin, aptamer sequences displace from the surface of anodic alumina resulting in pore opening and dye delivery. The dispositive shows a limit of detection (LOD) of 100 µg kg-1 of gliadin, good selectivity and a detection time of approximately 60 min. Moreover, the sensor is validated in real food samples. This novel probe allows fast gluten detection through a simple signalling process with potential use for food control.

pH-Dependent Molecular Gate Mesoporous Microparticles for Biological Control of Giardia intestinalis.

Giardiasis is a parasitism produced by the protozoa Giardia intestinalis that lives as trophozoite in the small intestine (mainly in the duodenum) attached to the intestinal villus by means of billed discs. The first line treatment is metronidazole, a drug with high bioavailability, which is why to obtain therapeutic concentrations in duodenum, it is necessary to administer high doses of drug to patients with the consequent occurrence of side effects. It is necessary to developed new therapeutical approaches to achieve a local delivery of the drug. In this sense, we have developed gated mesoporous silica microparticles loaded with metronidazole and with a molecular gate pH dependent. In vitro assays demonstrated that the metronidazole release is practically insignificant at acidic pHs, but in duodenum conditions, the metronidazole delivery from the microparticles is effective enough to produce an important parasite destruction. In vivo assays indicate that this microparticulate system allows to increase the concentration of the drug in duodenum and reduce the concentration in plasma avoiding systemic effects. This system could be useful for other intestinal local treatments in order to reduce doses and increase drug availability in target tissues.