Three-Dimensional-Printed Composite Scaffolds Containing Poly-ε-Caprolactone and Strontium-Doped Hydroxyapatite for Osteoporotic Bone Restoration.

A challenge in tissue engineering and the pharmaceutical sector is the development of controlled local release of drugs that raise issues when systemic administration is applied. Strontium is an example of an effective anti-osteoporotic agent, used in treating osteoporosis due to both anti-resorptive and anabolic mechanisms of action. Designing bone scaffolds with a higher capability of promoting bone regeneration is a topical research subject. In this study, we developed composite multi-layer three-dimensional (3D) scaffolds for bone tissue engineering based on nano-hydroxyapatite (HA), Sr-containing nano-hydroxyapatite (SrHA), and poly-ε-caprolactone (PCL) through the material extrusion fabrication technique. Previously obtained HA and SrHA with various Sr content were used for the composite material. The chemical, morphological, and biocompatibility properties of the 3D-printed scaffolds obtained using HA/SrHA and PCL were investigated. The 3D composite scaffolds showed good cytocompatibility and osteogenic potential, which is specifically recommended in applications when faster mineralization is needed, such as osteoporosis treatment.

Antimicrobial Packaging for Plum Tomatoes Based on ZnO Modified Low-Density Polyethylene.

Food safety and quality are major concerns in the food industry. Despite numerous studies, polyethylene remains one of the most used materials for packaging due to industry reluctance to invest in new technologies and equipment. Therefore, modifications to the current materials are easier to implement than adopting whole new solutions. Antibacterial activity can be induced in low-density polyethylene films only by adding antimicrobial agents. ZnO nanoparticles are well known for their strong antimicrobial activity, coupled with low toxicity and UV shielding capability. These characteristics recommend ZnO for the food industry. By incorporating such safe and dependable antimicrobial agents in the polyethylene matrix, we have obtained composite films able to inhibit microorganisms' growth that can be used as packaging materials. Here we report the obtaining of highly homogenous composite films with up to 5% ZnO by a melt mixing process at 150 °C for 10 min. The composite films present good transparency in the visible domain, permitting consumers to visualize the food, but have good UV barrier properties. The composite films exhibit good antimicrobial and antibiofilm activity from the lowest ZnO composition (1%), against both Gram-positive and Gram-negative bacterial strains. The homogenous dispersion of ZnO nanoparticles into the polyethylene matrix was assessed by Fourier transform infrared microscopy and scanning electron microscopy. The optimal mechanical barrier properties were obtained for composition with 3% ZnO. The thermal analysis indicates that the addition of ZnO nanoparticles has increased thermal stability by more than 100 °C. The UV-Vis spectra indicate a low transmittance in the UV domain, lower than 5%, making the films suitable for blocking photo-oxidation processes. The obtained films proved to be efficient packaging films, successfully preserving plum (Rome) tomatoes for up to 14 days.

Novel Photothermal Graphene-Based Hydrogels in Biomedical Applications.

In the last decade, photothermal therapy (PTT) has attracted tremendous attention because it is non-invasive, shows high efficiency and antibacterial activity, and minimizes drug side effects. Previous studies demonstrated that PTT can effectively inhibit the growth of bacteria and promotes cell proliferation, accelerating wound healing and tissue regeneration. Among different NIR-responsive biomaterials, graphene-based hydrogels with photothermal properties are considered as the best candidates for biomedical applications, due to their excellent properties. This review summarizes the current advances in the development of innovative graphene-based hydrogels for PTT-based biomedical applications. Also, the information about photothermal properties and the potential applications of graphene-based hydrogels in biomedical therapies are provided. These findings provide a great potential for supporting their applications in photothermal biomedicine.

The Antimicrobial Potency of Mesoporous Silica Nanoparticles Loaded with Melissa officinalis Extract.

Melissa officinalis is an important medicinal plant that is used and studied intensively due to its numerous pharmacological effects. This plant has numerous active compounds with biomedical potential; some are volatile, while others are sensitive to heat or oxygen. Therefore, to increase stability and prolong biological activities, the natural extract can be loaded into various nanostructured systems. In this study, different loading systems were obtained from mesoporous silica, like Mobile Composition of Matter family (MCM) with a hexagonal (MCM-41) or cubic (MCM-48) pore structure, simple or functionalized with amino groups (using 3-aminopropyl) such as triethoxysilane (APTES). Thus, the four materials were characterized from morphological and structural points of view by scanning electron microscopy, a BET analysis with adsorption-desorption isotherms, Fourier-transform infrared spectroscopy (FTIR) and a thermogravimetric analysis coupled with differential scanning calorimetry. Natural extract from Melissa officinalis was concentrated and analyzed by High-Performance Liquid Chromatography to identify the polyphenolic compounds. The obtained materials were tested against Gram-negative bacteria and yeasts and against both reference strains and clinical strains belonging to Gram-positive bacteria that were previously isolated from intra-hospital infections. The highest antimicrobial efficiency was found against Gram-positive and fungal strains. Good activity was also recorded against methicillin-resistant S. aureus, the Melissa officinalis extract inhibiting the production of various virulence factors.

Comparison between Two Different Synthesis Methods of Strontium-Doped Hydroxyapatite Designed for Osteoporotic Bone Restoration.

Development of efficient controlled local release of drugs that prevent systemic side effects is a challenge for anti-osteoporotic treatments. Research for new bone-regeneration materials is of high importance. Strontium (Sr) is known as an anti-resorptive and anabolic agent useful in treating osteoporosis. In this study, we compared two different types of synthesis used for obtaining nano hydroxyapatite (HA) and Sr-containing nano hydroxyapatite (SrHA) for bone tissue engineering. Synthesis of HA and SrHA was performed using co-precipitation and hydrothermal methods. Regardless of the synthesis route for the SrHA, the intended content of Sr was 1, 5, 10, 20, and 30 molar %. The chemical, morphological, and biocompatibility properties of HA and SrHA were investigated. Based on our results, it was shown that HA and SrHA exhibited low cytotoxicity and demonstrated toxic behavior only at higher Sr concentrations.

Phenotypic and Genotypic Characterization of Recently Isolated Multidrug-Resistant Acinetobacter baumannii Clinical and Aquatic Strains and Demonstration of Silver Nanoparticle Potency.

This study aims to demonstrate the effectiveness of silver nanoparticles (Ag NPs) on multidrug-resistant (MDR) Acinetobacter baumannii (AB) strains isolated from the clinical and aquatic environment. Three types of Ag NPs were investigated for their antimicrobial, antibiofilm, and antivirulence properties on a total number of 132 AB strains isolated in the same temporal sequence from intra-hospital infections (IHIs), wastewater (WW), and surface water (SW) samples between 2019 and 2022 from different Romanian locations and characterized at the phenotypic and genotypic levels. The comparative analysis of the antimicrobial resistance (AR) profiles according to the isolation source and the geographical location demonstrated a decrease in MDR level in AB recovered from WW samples in 2022 from north-eastern/central/southern regions (N-E/C-W/analyzed strains S): 87.5/60/32.5%. The AB strains were lecithinase, caseinase, amylase, and lipase producers, had variable biofilm formation ability, and belonged to six genotypes associated with the presence of different virulence genes (ompA, csuE, bap, and bfmS). The Ag NPs synthesized with the solvothermal method exhibited an inhibitory effect on microbial growth, the adherence capacity to the inert substratum, and on the production of soluble virulence factors. We report here the first description of a powerful antibacterial agent against MDR AB strains circulating between hospitals and anthropically polluted water in Romania.

Green Synthesis of Metal and Metal Oxide Nanoparticles: A Review of the Principles and Biomedical Applications.

In recent years, interest in nanotechnology has increased exponentially due to enhanced progress and technological innovation. In tissue engineering, the development of metallic nanoparticles has been amplified, especially due to their antibacterial properties. Another important characteristic of metal NPs is that they enable high control over the features of the developed scaffolds (optimizing their mechanical strength and offering the controlled release of bioactive agents). Currently, the main concern related to the method of synthesis of metal oxide NPs is the environmental impact. The physical and chemical synthesis uses toxic agents that could generate hazards or exert carcinogenicity/environmental toxicity. Therefore, a greener, cleaner, and more reliable approach is needed. Green synthetic has come as a solution to counter the aforementioned limitations. Nowadays, green synthesis is preferred because it leads to the prevention/minimization of waste, the reduction of derivatives/pollution, and the use of non-toxic (safer) solvents. This method not only uses biomass sources as reducing agents for metal salts. The biomolecules also cover the synthesized NPs or act as in situ capping and reducing agents. Further, their involvement in the formation process reduces toxicity, prevents nanoparticle agglomeration, and improves the antimicrobial activity of the nanomaterial, leading to a possible synergistic effect. This study aims to provide a comprehensive review of the green synthesis of metal and metal oxide nanoparticles, from the synthesis routes, selected solvents, and parameters to their latest application in the biomedical field.

Antibacterial Activity of Zinc Oxide Nanoparticles Loaded with Essential Oils.

One major problem with the overuse of antibiotics is that the microorganisms acquire resistance; thus the dose must be increased unsustainably. To overcome this problem, researchers from around the world are actively investigating new types of antimicrobials. Zinc oxide (ZnO) nanoparticles (NPs) have been proven to exhibit strong antimicrobial effects; moreover, the Food and Drugs Administration (FDA) considers ZnO as GRAS (generally recognized as safe). Many essential oils have antimicrobial activity and their components do not generate resistance over time. One of the drawbacks is the high volatility of some components, which diminishes the antimicrobial action as they are eliminated. The combination of ZnO NPs and essential oils can synergistically produce a stronger antimicrobial effect, and some of the volatile compounds can be retained on the nanoparticles' surface, ensuring a better-lasting antimicrobial effect. The samples were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), and thermal analysis (TG-DSC) coupled with analysis of evolved gases using FTIR. The ZnO NPs, with a size of ~35 nm, exhibited a loading between 1.44% and 15.62%-the lower values were specific for limonene-containing oils (e.g., orange, grapefruit, bergamot, or limette), while high values were obtained from cinnamon, minzol, thyme, citronella, and lavender oils-highlighting differences among non-polar terpenes and alcohol or aldehyde derivatives. The antibacterial assay indicated the existence of a synergic action among components and a high dependency on the percentage of loaded oil. Loaded nanoparticles offer immense potential for the development of materials with specific applications, such as wound dressings or food packaging. These nanoparticles can be utilized in scenarios where burst delivery is desired or when prolonged antibacterial activity is sought.

Development of gallic acid-loaded ethylcellulose fibers as a potential wound dressing material.

In this study, novel fibers were designed based on ethylcellulose (EC), loaded with different concentrations of gallic acid (GA) using the electrospinning technique, in order to investigate the potential of these materials as wound dressings. The chemical structure and morphology, along with the antimicrobial and biocompatibility tests of the EC_GA fibers were investigated. To observe the chemical interactions between the components, fourier transform infrared spectroscopy (FTIR) was used. The morphological analyzes were performed using scanning electron microscope (SEM). The uniaxial tensile test machine was used to obtain mechanical performance of the fibers. MTT assay was applied to get the biocompatibility properties of the fibers and antimicrobial test was applied to obtain the antimicrobial activity of the fibers. Based on the obtained results, the highest viability value of 67.4 % was obtained for 10%EC_100GA on the third day of incubation, demonstrating that with the addition of a higher concentration of GA, the cell viability increases. The antimicrobial tests, evaluated against Staphylococcus (S.) aureus, Escherichia (E.) coli, Pseudomonas (Ps.) aeruginosa and Candida (C.) albicans, showed a >90 % microbial reduction capacity correlated with a logarithmic reduction ranging from 0.63 to 1, for 10%EC_100 GA. In vitro release tests of GA from the fibers showed that GA was totally released from 10%EC_100 GA fibers after 2880 min, demonstrating a controlled release profile. These findings demonstrated that EC_GA fibers may be suitable for application in biomedical fields such as wound dressing materials. However, further studies should be performed to increase the biocompatibility properties of the fibers.

Antimicrobial Wound Dressings based on Bacterial Cellulose and Independently Loaded with Nutmeg and Fir Needle Essential Oils.

The aim of the present study was to obtain antimicrobial dressings from bacterial cellulose loaded with nutmeg and of fir needle essential oils. The attractive properties of BC, such as biocompatibility, good physicochemical and mechanical stability, and high water absorption, led to the choice of this material to be used as a support. Essential oils have been added to provide antimicrobial properties to these dressings. The results confirmed the presence of oils in the structure of the bacterial cellulose membrane and the ability of the materials to inhibit the adhesion of Staphylococcus aureus and Escherichia coli. By performing antibacterial tests on membranes loaded with fir needle essential oil, we demonstrated the ability of these membranes to inhibit bacterial adhesion to the substrate. The samples loaded with nutmeg essential oil exhibited the ability to inhibit the adhesion of bacteria to the surface of the materials, with the 5% sample showing a significant decrease. The binding of essential oils to the membrane was confirmed by thermal analysis and infrared characterization.

Metal-Organic Frameworks: Versatile Platforms for Biomedical Innovations.

This review article explores the multiple applications and potential of metal-organic frameworks (MOFs) in the biomedical field. With their highly versatile and tunable properties, MOFs present many possibilities, including drug delivery, biomolecule recognition, biosensors, and immunotherapy. Their crystal structure allows precise tuning, with the ligand typology and metal geometry playing critical roles. MOFs' ability to encapsulate drugs and exhibit pH-triggered release makes them ideal candidates for precision medicine, including cancer treatment. They are also potential gene carriers for genetic disorders and have been used in biosensors and as contrast agents for magnetic resonance imaging. Despite the complexities encountered in modulating properties and interactions with biological systems, further research on MOFs is imperative. The primary focus of this review is to provide a comprehensive examination of MOFs in these applications, highlighting the current achievements and complexities encountered. Such efforts will uncover their untapped potential in creating innovative tools for biomedical applications, emphasizing the need to invest in the continued exploration of this promising field.

Reductive Photodegradation of 4,4'-Isopropylidenebis(2,6-dibromophenol) on Fe3O4 Surface.

BACKGROUND: Advanced Oxidation Processes (AOPs) are the water treatment techniques that are commonly used forthe decomposition of the non-biodegradable organic pollutants. However, some pollutants are electron deficient and thus resistant to attack by reactive oxygen species (e.g., polyhalogenated compounds) but they may be degraded under reductive conditions. Therefore, reductive methods are alternative or supplementary methods to the well-known oxidative degradation ones. METHODS: In this paper, the degradation of 4,4'-isopropylidenebis(2,6-dibromophenol) (TBBPA, tetrabromobisphenol A) using two Fe3O4 magnetic photocatalyst (F1 and F2) is presented. The morphological, structural and surface properties of catalysts were studied. Their catalytic efficiency was evaluated based on reactions under reductive and oxidative conditions. Quantum chemical calculations were used to analyse early steps of degradation mechanism. RESULTS: The studied photocatalytic degradation reactions undergo pseudo-first order kinetics. The photocatalytic reduction process follows the Eley-Rideal mechanism rather than the commonly used Langmuir-Hinshelwood mechanism. CONCLUSIONS: The study confirms that both magnetic photocatalyst are effective and assure reductive degradation of TBBPA.

The Development of Alginate/Ag NPs/Caffeic Acid Composite Membranes as Adsorbents for Water Purification.

Since the water pollution problem still affects the environmental system and human health, the need to develop innovative membranes has become imperious. Lately, researchers have focused on developing novel materials to help diminish the contamination problem. The aim of present research was to obtain innovative adsorbent composite membranes based on a biodegradable polymer, alginate, to remove toxic pollutants. Of all pollutants, lead was chosen due to its high toxicity. The composite membranes were successfully obtained through a direct casting method. The silver nanoparticles (Ag NPs) and caffeic acid (CA) from the composite membranes were kept at low concentrations, which proved enough to bestow antimicrobial activity to the alginate membrane. The obtained composite membranes were characterised by Fourier transform infrared spectroscopy and microscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TG-DSC). Swelling behaviour, lead ion (Pb2+) removal capacity, regeneration and reusability were also determined. Further, the antimicrobial activity was tested against selected pathogenic strains (S. aureus, E. faecalis sp., P. aeruginosa, E. coli and C. albicans). The presence of Ag NPs and CA improves the antimicrobial activity of the newly developed membranes. Overall, the composite membranes are suitable for complex water treatment (removal of heavy metal ions and antimicrobial treatment).

Synergistic Antimicrobial Activity of Magnetite and Vancomycin-Loaded Mesoporous Silica Embedded in Alginate Films.

The aim of the present study was to obtain a hydrogel-based film as a carrier for the sustained and controlled release of vancomycin, an antibiotic commonly used in various types of infections. Considering the high-water solubility of vancomycin (>50 mg/mL) and the aqueous medium underlying the exudates, a prolonged release of vancomycin from an MCM-41 carrier was sought. The present work focused on the synthesis of malic acid coated magnetite (Fe3O4/malic) by co-precipitation, synthesis of MCM-41 by a sol-gel method and loading of MCM-41 with vancomycin, and their use in alginate films for wound dressing. The nanoparticles obtained were physically mixed and embedded in the alginate gel. Prior to incorporation, the nanoparticles were characterized by XRD, FT-IR and FT-Raman spectroscopy, TGA-DSC and DLS. The films were prepared by a simple casting method and were further cross-linked and examined for possible heterogeneities by means of FT-IR microscopy and SEM. The degree of swelling and the water vapor transmission rate were determined, considering their potential use as wound dressings. The obtained films show morpho-structural homogeneity, sustained release over 48 h and a strong synergistic enhancement of the antimicrobial activity as a consequence of the hybrid nature of these films. The antimicrobial efficacy was tested against S. aureus, two strains of E. faecalis (including vancomycin-resistant Enterococcus, VRE) and C. albicans. The incorporation of magnetite was also considered as an external triggering component in case the films were used as a magneto-responsive smart dressing to stimulate vancomycin diffusion.

Graphene-Related Nanomaterials for Biomedical Applications.

This paper builds on the context and recent progress on the control, reproducibility, and limitations of using graphene and graphene-related materials (GRMs) in biomedical applications. The review describes the human hazard assessment of GRMs in in vitro and in vivo studies, highlights the composition-structure-activity relationships that cause toxicity for these substances, and identifies the key parameters that determine the activation of their biological effects. GRMs are designed to offer the advantage of facilitating unique biomedical applications that impact different techniques in medicine, especially in neuroscience. Due to the increasing utilization of GRMs, there is a need to comprehensively assess the potential impact of these materials on human health. Various outcomes associated with GRMs, including biocompatibility, biodegradability, beneficial effects on cell proliferation, differentiation rates, apoptosis, necrosis, autophagy, oxidative stress, physical destruction, DNA damage, and inflammatory responses, have led to an increasing interest in these regenerative nanostructured materials. Considering the existence of graphene-related nanomaterials with different physicochemical properties, the materials are expected to exhibit unique modes of interactions with biomolecules, cells, and tissues depending on their size, chemical composition, and hydrophil-to-hydrophobe ratio. Understanding such interactions is crucial from two perspectives, namely, from the perspectives of their toxicity and biological uses. The main aim of this study is to assess and tune the diverse properties that must be considered when planning biomedical applications. These properties include flexibility, transparency, surface chemistry (hydrophil-hydrophobe ratio), thermoelectrical conductibility, loading and release capacity, and biocompatibility.

Electrically Triggered Quercetin Release from Polycaprolactone/Bismuth Ferrite Microfibrous Scaffold for Skeletal Muscle Tissue.

Skeletal muscle tissue engineering presents a promising avenue to address the limitations pertaining to the regenerative potential of stem cells in case of injury or damage. The objective of this research was to evaluate the effects of utilizing novel microfibrous scaffolds, containing the compound quercetin (Q), on skeletal muscle regeneration. Morphological test results showed us that the combination of bismuth ferrite (BFO), polycaprolactone (PCL), and Q were bonded and well-ordered with each other, and a uniform microfibrous structure was obtained. Antimicrobial susceptibility testing of PCL/BFO/Q was conducted, and microbial reduction was found to be over 90% in the highest concentration of Q-loaded microfibrous scaffolds with the most inhibitory effect on S. aureus strains. Further, biocompatibility was investigated by performing MTT testing, fluorescence testing, and SEM imaging on mesenchymal stem cells (MSCs) to determine whether they could act as suitable microfibrous scaffolds for skeletal muscle tissue engineering. Incremental changes in the concentration of Q led to increased strength and strain, allowing muscles to withstand stretching during the healing process. In addition, electrically conductive microfibrous scaffolds enhanced the drug release capability by revealing that Q can be released significantly more quickly by applying the appropriate electric field, compared with conventional drug-release techniques. These findings suggest a possible use for PCL/BFO/Q microfibrous scaffolds in skeletal muscle regeneration by demonstrating that the combined action of both guidance biomaterials was more successful than Q itself acting alone.

Smart Magnetic Drug Delivery Systems for the Treatment of Cancer.

Cancer remains the most devastating disease, being one of the main factors of death and morbidity worldwide since ancient times. Although early diagnosis and treatment represent the correct approach in the fight against cancer, traditional therapies, such as chemotherapy, radiotherapy, targeted therapy, and immunotherapy, have some limitations (lack of specificity, cytotoxicity, and multidrug resistance). These limitations represent a continuous challenge for determining optimal therapies for the diagnosis and treatment of cancer. Cancer diagnosis and treatment have seen significant achievements with the advent of nanotechnology and a wide range of nanoparticles. Due to their special advantages, such as low toxicity, high stability, good permeability, biocompatibility, improved retention effect, and precise targeting, nanoparticles with sizes ranging from 1 nm to 100 nm have been successfully used in cancer diagnosis and treatment by solving the limitations of conventional cancer treatment, but also overcoming multidrug resistance. Additionally, choosing the best cancer diagnosis, treatment, and management is extremely important. The use of nanotechnology and magnetic nanoparticles (MNPs) represents an effective alternative in the simultaneous diagnosis and treatment of cancer using nano-theranostic particles that facilitate early-stage detection and selective destruction of cancer cells. The specific properties, such as the control of the dimensions and the specific surface through the judicious choice of synthesis methods, and the possibility of targeting the target organ by applying an internal magnetic field, make these nanoparticles effective alternatives for the diagnosis and treatment of cancer. This review discusses the use of MNPs in cancer diagnosis and treatment and provides future perspectives in the field.

Antibacterial Activity of Solvothermal Obtained ZnO Nanoparticles with Different Morphology and Photocatalytic Activity against a Dye Mixture: Methylene Blue, Rhodamine B and Methyl Orange.

In this paper, we report the synthesis of ZnO nanoparticles (NPs) by forced solvolysis of Zn(CH3COO)2·2H2O in alcohols with a different number of -OH groups. We study the influence of alcohol type (n-butanol, ethylene glycol and glycerin) on the size, morphology, and properties of the obtained ZnO NPs. The smallest polyhedral ZnO NPs (<30 nm) were obtained in n-butanol, while in ethylene glycol the NPs measured on average 44 nm and were rounded. Polycrystalline particles of 120 nm were obtained in glycerin only after water refluxing. In addition, here, we report the photocatalytic activity, against a dye mixture, of three model pollutants: methyl orange (MO), methylene blue (MB), and rhodamine B (RhB), a model closer to real situations where water is polluted with many chemicals. All samples exhibited good photocatalytic activity against the dye mixture, with degradation efficiency reaching 99.99%. The sample with smallest nanoparticles maintained a high efficiency >90%, over five catalytic cycles. Antibacterial tests were conducted against Gram-negative strains Salmonella enterica serovar Typhimurium, Pseudomonas aeruginosa, and Escherichia coli, and Gram-positive strains Enterococcus faecalis, Bacillus subtilis, Staphylococcus aureus, and Bacillus cereus. The ZnO samples presented strong inhibition of planktonic growth for all tested strains, indicating that they can be used for antibacterial applications, such as water purification.