Chitosan-silver Nanoparticles Research Articles

Synthesis and Characterization of Multifunctional Chitosan-Silver Nanoparticles: An In-Vitro Approach for Biomedical Applications.

Antibiotics are successful in promoting health quality by preventing various infectious diseases and minimizing mortality and morbidity all over the world. However, the indiscriminate use of antibiotics has led to the emergence of multi-drug-resistant bacteria, which pose a serious threat to health care sector. Therefore, it is necessary to develop novel antimicrobial agents with versatile characteristics, such as antibacterial activity, low toxicity, wound healing potency, and antioxidant property. In this context, silver chitosan nanoparticles were synthesized in the present study, and their physical characterization revealed that the size of synthesized chitosan-silver nanoparticles was 14-25 nm, with positive surface charge. The functional groups and crystalline nature of the nanoparticles were confirmed by FT-IR and XRD analysis. Further, the silver chitosan nanoparticles showed antibacterial activity against two important clinical pathogens, S. aureus and E. coli. The MTT assay carried out in the present study showed that the synthesized nanoparticles are non-toxic to host cells. A scratch assay on fibroblast cells (L292) demonstrated that the silver chitosan nanoparticles showed promising wound healing activity. A fluorescent DCFH-DA staining assay revealed anantioxidant property of the synthesized nanoparticles. Overall, the study emphasizes the versatile nature of synthesized chitosan-silver nanoparticles, suggesting their great compatibility for biomedical applications.

Preparation, characterization, and application of chitosan-silver nanoparticles for Cu(II) and Zn(II) removal from oil refinery wastewater

Copper and zinc stand as one of the most alarming contaminants, presenting a formidable challenge in the realm of drinking water across numerous countries. To deal with this challenge, the sequestration of copper and zinc by adsorption has been extensively investigated in the solid media. Here, an adsorbent system based on a natural polymer - chitosan with physical cross-linking using silver nanoparticles is investigated for high binding, to get a new modified adsorbents (CS/AgNPs) that used these metal ions from simulated oil refinery wastewater. The adsorption mechanism is extensively studied via FTIR, zeta potential, dynamic light scattering (DLS), EDS, SEM, and BET. The prepared adsorbents (CS/AgNPs) have a bigger surface area than pristine chitosan that expanded from 4.74 to 36.34 m2/g, respectively. The prepared CS/AgNPs showed stronger adsorption ability than pristine chitosan attributable to its permeable structure and expanded surface area. In batch experiments, the Langmuir adsorption isotherms revealed that the highest uptake removal amount for Copper (II) and zinc (II) onto CS/AgNPs are 110.67 and 92.13 mg/g, correspondingly. These findings indicate that CS/AgNPs show a great potential as a proficient and selective materials for eliminating copper and zinc ions from aqueous solutions.

Bioinspired Flexible and Low-Voltage Organic Synaptic Transistors for UV Light-Driven Vision Systems.

Neuromorphic vision systems, particularly those stimulated by ultraviolet (UV) light, hold great potential applications in portable electronics, wearable technology, biological analysis, military surveillance, etc. Organic artificial synaptic devices hold immense potential in this field due to their ease of processing, flexibility, and biocompatibility. In this work, we have fabricated a flexible organic field-effect transistor (OFET) that utilizes chitosan-silver nanoparticles (AgNPs) composite material as the active dielectric material. During UV light illumination, both silver nanoparticles and the pentacene layer generate a large number of charge carriers. The photogenerated carriers lead to a more significant hole accumulation at the pentacene interface, resulting in a current rise. In the absence of light, the trapped electron in the silver nanoparticles persists for a longer duration, preventing the instant recombination with holes. This extended retention of electrons leads to the observed synaptic performance of the transistor. The use of aluminum oxide (Al2O3) as one of the dielectric layers enables the device to operate effectively at low voltage (<1 V). The device mimics various crucial synaptic properties of the brain, including short-term potentiation and long-term potentiation (STP and LTP), paired-pulse facilitation (PPF), spike-duration dependent plasticity (SDDP), spike-number dependent plasticity (SNDP), and spike-rate dependent plasticity (SRDP), etc. This work introduces an approach to develop flexible organic synaptic transistors that operate efficiently at low voltages, paving the way toward high-performance, UV light-driven neuromorphic vision systems.

Laser enhanced photothermal effect of silver nanoparticles synthesized by chemical and green method on Gram-positive and Gram-negative bacteria

PurposeThe antibacterial properties of silver nanoparticles (AgNPs) are extensively identified. In large quantities, they might be harmful. So many fields of nanotechnology have shown a great deal of interest in the development of an environmentally friendly, efficient method for synthesizing metal nanoparticles. Because of its antibacterial and antifungal properties toward a wide range of microbes, chitosan silver nanoparticles (AgNPs@Cs) constitute a newly developing class of bio-nanostructured hybrid materials. Furthermore, the use of photothermal therapy (PTT) has been suggested as a means of elimination of germs. These light-stimulated treatments are minimally invasive and have a few side effects. In the present work, the antibacterial effect of AgNPs at low concentrations; prepared by chemical and green methods as antimicrobial and photothermal agents in photothermal therapy; with laser irradiation were explored as combined treatment against MRSA, Pseudomonas aeruginosa, and Klebsiella pneumoniae.MethodsSilver nanoparticles were produced in two ways. First, by sodium borohydrides, second, by chitosan (as a natural eco-friendly reducing, and capping agent). The nanostructure of AgNPs and AgNPs@Cs was confirmed by UV–visible spectrometer, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIRs), and direct light scattering (DLS). The antibacterial activity of the prepared nanoparticles and the laser irradiation was tested against three bacterial species of zoonotic importance; MRSA, Pseudomonas aeruginosa, and Klebsiella pneumoniae; and was evaluated by measuring their minimum inhibitory concentrations (MIC).ResultsSilver nanoparticles produced by the two methods had spherical shapes with nearly the same particle size. The analysis of DLS showed that AgNPs were very stable with zeta potential − 28.8 mv, and 47.7 mv by chemical and chitosan synthesis, respectively. Furthermore, AgNPs@Cs showed higher antibacterial activity toward the tested bacterial species than AgNPs by chemical method. Additionally, the bacterial viability using photothermal laser therapy was reduced compared to laser and AgNPs alone. The bactericidal activities were higher when laser diode was coupled with AgNPs@Cs than by chemical reduction.ConclusionThe laser combined treatment had a higher antimicrobial effect than AgNPs alone or laser irradiation alone.

Molecular dynamics model quantum field for prediction of the interaction between chitosan–silver nanoparticles

ABSTRACT In this work, a composite material between chitosan and silver oxide nanoparticles (Ag2NPs) was developed. The universal force field option in the Materials Studio® software was applied to the modelled Ag2NPs within a sphere of variable radius, being 11 å the most stable. In addition, each of these models was taken to their state of minimum energy to verify their stability, and then, a simulation was carried out using a canonical ensemble at 298 K. The X-ray diffraction pattern of these models was simulated and is according to those reported for Ag2O. Molecular and quantum dynamics simulations for the models of the chitosan chains in interaction with Ag2ONPs were made. Each proposed model was based on the Schrödinger equation, considering the quantum fields for the interaction of the nanoparticle in the chitosan substrate. It was observed that the fields were deformed, demonstrating that the presence of the nanoparticle on the surface produces deformation in the polymeric matrix, which suggests a phenomenon of surface adsorption that was confirmed with the RDF where a chemical interaction between the polymer and the silver oxide nanoparticles was shown. This result supports that is possible to obtain the chitosan–Ag2ONPs experimentally.

Green Synthesis of Chitosan/Silver Nanoparticles Using Citrus paradisi Extract and Its Potential Anti-Cryptosporidiosis Effect.

Cryptosporidium parvum (C. parvum) is one of the most prevalent species infecting humans and animals. Currently, the only FDA-licensed drug to treat cryptosporidiosis is nitazoxanide (NTZ), with no efficacy in immunocompromised hosts. Citrus paradisi (C. paradisi) has demonstrated anti-protozoal activities. This study aimed to investigate the anti-cryptosporidiosis effect of C. paradisi peel extract, either alone or in mediating the green synthesis of chitosan silver nanoparticles (Cs/Ag NPs), compared to NTZ. Mice were sorted into nine different groups. The effectiveness of the treatments was evaluated using parasitology, histopathology, immunohistochemistry, and immunology. C. paradisi outperformed nitazoxanide regarding oocyst shedding (79% vs. 61%). The effectiveness of NTZ Cs/Ag NPs and Citrus Cs/Ag NPs was enhanced to 78% and 91%, respectively. The highest oocyst inhibition was obtained by combining NTZ and Citrus Cs/Ag NPs (96%). NF-κB, TNF-α, and Il-10 levels increased in response to infection and decreased in response to various treatments, with the highest reduction in the group treated with combined NTZ citrus Cs/Ag NPs. Combining C. paradisi with NTZ could have a synergistic effect, making it a potentially effective anti-cryptosporidiosis agent. Utilizing C. paradisi in the green synthesis of Cs/Ag NPs improves the therapeutic response and can be used to produce novel therapeutic antiparasitic drugs.

Shikonin and chitosan-silver nanoparticles synergize against triple-negative breast cancer through RIPK3-triggered necroptotic immunogenic cell death

Necroptotic immunogenic cell death (ICD) can activate the human immune system to treat the metastasis and recurrence of triple-negative breast cancer (TNBC). However, developing the necroptotic inducer and precisely delivering it to the tumor site is the key issue. Herein, we reported that the combination of shikonin (SHK) and chitosan silver nanoparticles (Chi-Ag NPs) effectively induced ICD by triggering necroptosis in 4T1 cells. Moreover, to address the lack of selectivity of drugs for in vivo application, we developed an MUC1 aptamer-targeted nanocomplex (MUC1@Chi-Ag@CPB@SHK, abbreviated as MUC1@ACS) for co-delivering SHK and Chi-Ag NPs. The accumulation of MUC1@ACS NPs at the tumor site showed a 6.02-fold increase compared to the free drug. Subsequently, upon reaching the tumor site, the acid-responsive release of SHK and Chi-Ag NPs from MUC1@ACS NPs cooperatively induced necroptosis in tumor cells by upregulating the expression of RIPK3, p-RIPK3, and tetrameric MLKL, thereby effectively triggering ICD. The sequential maturation of dendritic cells (DCs) subsequently enhanced the infiltration of CD8+ and CD4+ T cells in tumors, while inhibiting regulatory T cells (Treg cells), resulting in the effective treatment of primary and distal tumor growth and the inhibition of TNBC metastasis. This work highlights the importance of nanoparticles in mediating drug interactions during necroptotic ICD.

Isolation and Encapsulation of Chitosan Silver Nanoparticle Extracted from Squid Pen and its Characterization

The main study focuses on the extraction of chitosan from chitin isolated from the exoskeleton of a squid pen and the synthesis of silver chitosan nanoparticles. Chitosan is an amino polysaccharide prepared by processing the squid pen which involves demineralization, deproteinization, and deacetylation. Chitosan is a versatile natural polysaccharide, its second most abundant natural polymer. Previous studies have found that chitosan is biocompatible, biodegradable, and non-toxic, which has wide applicability in the pharmaceutical field, food industries, drug delivery, cancer treatment, and biological imaging and diagnosis. The chitosan and silver chitosan nanoparticles yield was found to be 25% and 51.25%. The conformation of silver chitosan nanoparticles was done through UV spectrum, FTIR, and XRD. Keywords: Chitosan, Chitin, Biopolymer, Characterization, UV spectrum, FTIR, XRD.

Antimicrobial activity of Chitosan-silver nanoparticles made from jewelry industry silver waste

Local management of bacterial infections is challenging. The antimicrobial effect of silver has long been recognized, but its use is limited due to its expensive nature and reduced applicability in liquids. This study aimed to synthesize chitosan-silver nanoparticles (CS-AgNPs) from reusable silver waste of the jewelry industry and investigate their antimicrobial properties against pathogenic microorganisms. X-Ray diffraction (XRD) analysis was used to confirm the crystalline structure of the recycled silver, with a strong diffraction peak observed at 2?=38.60?. Agar disk diffusion showed inhibitory effects for CS-AgNPs on the growth of Escherichia coli, Staphylococcus aureus, and Candida albicans that depended on the concentration of AgNO3 solution used for preparation. In these tests, S. aureus was more susceptible to the treatment than E. coli and C. albicans. The CS-AgNP inhibited the growth of tested microorganisms with minimum inhibitory concentration (MIC50) values between 1.7 and 4.25 mg/mL. These findings highlight the potential of CS-AgNPs as effective antimicrobial agents. The use of waste materials in nanoparticle synthesis in this research offers a promising approach for sustainable and eco-friendly nanotechnology.

Fabrication and evaluation of anticancer potential of diosgenin incorporated chitosan-silver nanoparticles; in vitro, in silico and in vivo studies

The discovery of effective therapeutic approaches with minimum side effects and their tendency to completely eradicate the disease is the main challenge in the history of cancer treatment. Fenugreek (FGK) seeds are a rich source of phytochemicals, especially Diosgenin (DGN), which shows outstanding anticancer activities. In the present study, chitosan-silver nanoparticles (ChAgNPs) containing Diosgenin (DGN-ChAgNPs) were synthesized and evaluated for their anticancer activity against breast cancer cell line (MCF-7). For the physical characterization, the hydrodynamic diameter and zeta potential of DGN-ChAgNPs were determined to be 160.4 ± 12 nm and +37.19 ± 5.02 mV, respectively. Transmission electron microscopy (TEM) showed that nanoparticles shape was mostly round with smooth edges. Moreover, DGN was efficiently entrapped in nanoformulation with good entrapment efficacy (EE) of ~88 ± 4 %. The in vitro anti-proliferative activity of DGN-ChAgNPs was performed by sulforhodamine B (SRB) assay with promising inhibitory concentration of 6.902 ± 2.79 μg/mL. DAPI staining, comet assay and flow cytometry were performed to validate the anticancer potential of DGN-ChAgNPs both qualitatively and quantitatively. The percentage of survival rate and tumor reduction weight was evaluated in vivo in different groups of mice. Cisplatin was used as a standard anticancer drug. The DGN-ChAgNPs (12.5 mg/kg) treated group revealed higher percentage of survival rate and tumor reduction weight as compared to pure DGN treated group. These findings suggest that DGN-ChAgNPs could be developed as potential treatment therapy for breast cancer.

Fabrication and Evaluation of Anticancer Potential of Eugenol Incorporated Chitosan-Silver Nanocomposites: In Vitro, In Vivo, and In Silico Studies.

The expanding global cancer burden necessitates a comprehensive strategy to promote possible therapeutic interventions. Nanomedicine is a cutting-edge approach for treating cancer with minimal adverse effects. In the present study, chitosan-silver nanoparticles (ChAgNPs) containing Eugenol (EGN) were synthesized and evaluated for their anticancer activity against breast cancer cells (MCF-7). The physical, pharmacological, and molecular docking studies were used to characterize these nanoparticles. EGN had been effectively entrapped into hybrid NPs (84 ± 7%). The EGN-ChAgNPs had a diameter of 128 ± 14nm, a PDI of 0.472 ± 0.118, and a zeta potential of 30.58 ± 6.92mV. Anticancer activity was measured in vitro using an SRB assay, and the findings revealed that EGN-ChAgNPs demonstrated stronger anticancer activity against MCF-7 cells (IC50 = 14.87 ± 5.34µg/ml) than pure EGN (30.72 ± 4.91µg/ml). To support initial cytotoxicity findings, advanced procedures such as cell cycle analysis and genotoxicity were performed. Tumor weight reduction and survival rate were determined using different groups of mice. Both survival rates and tumor weight reduction were higher in the EGN-ChAgNPs (12.5mg/kg) treated group than in the pure EGN treated group. Based on protein-ligand interactions, it might be proposed that eugenol had a favorable interaction with Aurora Kinase A. It was observed that C9 had the highest HYDE score of any sample, measuring at -6.8kJ/mol. These results, in conjunction with physical and pharmacological evaluations, implies that EGN-ChAgNPs may be a suitable drug delivery method for treating breast cancer in a safe and efficient way.

Synthesis of Chitosan-Silver Nanocomposite and Its Evaluation as an Antibacterial Coating for Mobile Phone Glass Protectors.

An easy and environment-friendly route for antibacterial coating suited for mobile phone glass protectors was successfully demonstrated. In this route, freshly prepared chitosan solution in 1% v/v acetic acid was added with 0.1 M silver nitrate solution and 0.1 M sodium hydroxide solution and incubated with agitation at 70 °C to form chitosan-silver nanoparticles (ChAgNPs). Varied concentrations of chitosan solution (i.e., 0.1, 0.2, 0.4, 0.6, and 0.8% w/v) were used to investigate its particle size, size distribution, and later on, its antibacterial activity. Transmission electron microscope (TEM) imaging revealed that the smallest average diameter of silver nanoparticles (AgNPs) was 13.04 nm from 0.8% w/v chitosan solution. Further characterizations of the optimal nanocomposite formulation using UV-vis spectroscopy and Fourier transfer infrared spectroscopy were also performed. Using a dynamic light scattering zetasizer, the average ζ-potential of the optimal ChAgNP formulation was at +56.07 mV, showing high aggregative stability and an average ChAgNP size of 182.37 nm. The ChAgNP nanocoating on glass protectors shows antibacterial activity against Escherichia coli (E. coli) at 24 and 48 h of contact. However, the antibacterial activity decreased from 49.80% (24 h) to 32.60% (48 h).

Chitosan/luminol/AgNPs nanocomposite for electrochemiluminescent determination of prostate-specific antigen.

Agreen, environmentally friendly protocol was developed for ultrasensitive and highly specific recognition of prostate-specific antigen (PSA) based on the ECL effect of luminol supported by chitosan-silver nanoparticles (CS/AgNPs) nanocomposites. The transducing surface was fabricated through two consecutive electrodeposition steps of gold nanoparticles (AuNPs) and chitosan (CS)-AgNPs-luminol electrochemiluminophore onto the glassy carbon electrode. In addition to anappropriate desirable biocompatibility, theelectrochemical synthesis presents low-cost preparation and ultrafast determination opportunity. AgNPs play a linking role to attach luminol, as an ECL agent to the CS support via donor-acceptor bonds between Ag atoms with NH groups of luminol and CS. Also, AgNPs can amplify the ECL intensity as a consequence of their excellent specific surface area and conductivity. To enhance the performance of the nanobiosensor, AuNPs were also used due totheir high-specific surface area and excellent affinity toward amine groups of CS. Based on this high-performance analysis strategy, ultrasensitive screening of PSA was attained with a desirable limit of detection of 0.6 ng mL-1 and a broad linear range between 1 pg mL-1 and 10 ng⋅mL-1 (R2=0.994). Approximately, the same results were recorded for the analysis of the unprocessed serum samples of patients with prostate cancer at different stages. This research provided significant insight into electrografting methods to construct ECL transducers for clinical monitoring of PSA and other tumor biomarkers in the clinical setting.

Synthesis of Antimicrobial Chitosan-Silver Nanoparticles Mediated by Reusable Chitosan Fungal Beads.

Nanoparticles, especially silver nanoparticles (Ag NPs), have gained significant attention in recent years as potential alternatives to traditional antibiotics for treating infectious diseases due to their ability to inhibit the growth of microorganisms effectively. Ag NPs can be synthesized using fungi extract, but the method is not practical for large-scale production due to time and biomass limitations. In this study, we explore the use of chitosan to encapsulate the mycelia of the white-rot fungus Stereum hirsutum and form chitosan fungal beads for use in multiple extractions and nanoparticle synthesis. The resulting nanoparticles were characterized using various techniques, including UV-vis spectrophotometry, transmission electron microscopy, dynamic light scattering, and X-ray diffraction analysis. The analysis revealed that the synthesized nanoparticles were composed of chitosan-silver nanoparticles (CS-Ag NPs) with a size of 25 nm. The chitosan fungal beads were reused in three extractions and nanoparticle synthesis before they lost their ability to produce CS-Ag NPs. The CS-Ag NPs showed potent antimicrobial activity against phytopathogenic and human pathogenic microorganisms, including Pseudomonas syringae, Escherichia coli, Staphylococcus aureus, and Candida albicans, with minimum inhibitory concentrations of 1.5, 1.6, 3.1, and 4 µg/mL, respectively. The antimicrobial activity of CS-Ag NPs was from 2- to 40-fold higher than Ag NPs synthesized using an aqueous extract of unencapsulated fungal biomass. The CS-Ag NPs were most effective at a pH of five regarding the antimicrobial activity. These results suggest that the chitosan fungal beads may be a promising alternative for the sustainable and cost-effective synthesis of CS-Ag NPs with improved antimicrobial activity.

Synthesis of Green Chitosan – Silver Nanoparticle Composite Material: Parameter Optimization and Physicochemical Characterization

In this study, response surface methodology (RSM) was carried out with four parameters: chitosan concentration, AgNO3 concentration, ascorbic acid concentration and time with the objective to obtain minimum mean particle size of silver nanoparticles (response Y). The chitosan-silver nanoparticle composite material (CTS-AgNPs nanocomposite) obtained experimentally from the optimal conditions was characterized by evaluating some of their physical-chemical properties using combined technique including visible ultraviolet spectroscopy (UV -Vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), infrared spectra (IR) and X-ray diffraction. The optimal conditions were chitosan concentration of 19.2 %, silver nitrate of 26 mM, ascorbic concentration of 33 mM and time of 4.25 hours. Spherical Ag particles obtained experimentally were well dispersed in chitosan matrix with the average diameter of around 2÷8 nm with a narrow size distribution and homogeneous dispersion

Multifunctional Poly(acrylic acid)/Chitosan nanoparticle network hydrogels with tunable mechanics

Nanoparticle network hydrogels (NNHs) employ nanoparticles as key building blocks of hydrogel networks to provide excellent mechanical properties and multifunctionality. Herein, poly(acrylic acid)/chitosan nanoparticle network hydrogels (PAAc/CS NNHs) with prominent mechanical properties were fabricated using catechol functional methacryloyl chitosan-silver nanoparticles (CFMC-Ag NPs) as multifunctional nanoparticle crosslinkers. The PAAc/CS NNHs were composed of hybrid networks derived from CFMC-Ag NPs crosslinked PAAc and entangled chitosan (CS) chains. The mechanical properties of PAAc/CS NNHs were highly impacted by the concentration of CFMC-Ag NPs. A maximum tensile strength of 2.22 MPa, a compressive strength of 10.61 MPa, and a toughness of 5.57 MJ·m−3 were obtained at a nanoparticle concentration of 10 mg/mL. In addition, PAAc/CS NNHs exhibited great self-recovery performance and excellent fatigue resistance. It was demonstrated that PAAc/CS NNHs possessed antibacterial activity, electrical conductivity and anti-freezing capability. This strategy could be applied for the preparation of other multifunctional hydrogels with significant mechanical properties.

Compressed Hydrogen-Induced Synthesis of Quaternary Trimethyl Chitosan-Silver Nanoparticles with Dual Antibacterial and Antifungal Activities.

Quaternary Trimethyl Chitosan (QTMC) and QTMC-Silver Nanoparticles (QTMC-AgNPs) have been synthesized, characterized, and tested as antibacterial agents against Staphylococcus aureus, Escherichia coli, and two plant fungi (Sclerotium rolfsil and Fusarium oxysporum). The as-prepared water-soluble QTMC was in situ reacted with silver nitrate in the presence of clean compressed hydrogen gas (3 bar) as a reducing agent to produce QTMC-AgNPs. UV-vis, ATR-FTIR, HR-TEM/SEM, XPS, DLS, XRD, and TGA/DTG were employed to assess the optical response, morphology/size, surface chemistry, particle size distribution, crystal nature, and thermal stability of the synthesized QTMC-AgNPs, respectively. The as-prepared QTMC-AgNPs were quasi-spherical in shape with an average particle size of 12.5 nm, as determined by ImageJ software utilizing HR-TEM images and further validated by DLS analysis. The development of crystalline nanoparticles was confirmed by the presence of distinct and consistent lattice fringes with an approximate interplanar d-spacing of 2.04 nm in QTMC-AgNPs. The QTMC-AgNPs exhibited significant antibacterial activity with a clear zone of inhibition of 30 mm and 26 mm around the disks against E. coli and S. aureus, respectively. In addition, QTMC-AgNPs showed highly efficient antifungal activity with 100% and 76.67% growth inhibition against two plant pathogens, S. rolfsii and F. oxysporum, respectively, whereas QTMC revealed no impact. Overall, QTMC-AgNPs showed a promising therapeutic potential and,thus, can be considered for drug design rationale.

Chitosan Silver and Gold Nanoparticle Formation Using Endophytic Fungi as Powerful Antimicrobial and Anti-Biofilm Potentialities.

Nanotechnology is emerging as a new technology with encouraging innovations. Global antibiotic use has grown enormously, with antibiotic resistance increasing by about 80 percent. In view of this alarming situation, intensive research has been carried out into biogenic nanoparticles and their antibacterial, antifungal, and antitumor activities. Many methods are available to enhance stability and dispersion via peroration of conjugate with a polymer, such as chitosan, and other bioactive natural products. Two marine fungi were isolated and identified as Aspergillus sp. and Alternaria sp. via sequencing of the 16S rRNA gene. In this work, these strains were used to form the conjugation of biogenic silver nanoparticles (AgNPs) from Aspergillus sp. Silv2 extract and gold nanoparticles (AuNPs) from Alternaria sp. Gol2 extracts with chitosan to prepare chitosan–AgNPs and chitosan–AuNP conjugates. A variety of imaging and analytical methods, such as UV–vis, X-ray powder diffraction (XRD), FTIR spectroscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were utilized to characterize biogenic nanoparticles and conjugates. The biosynthesized Ag and Au nanoparticles along with the prepared conjugates were evaluated for their antimicrobial effects on Gram-negative and Gram-positive bacterial isolates, including Escherichia coli and Staphylococcus aureus. Both chitosan–AgNP and AuNP showed powerful antimicrobial activities compared to the control. On the other hand, chitosan–AgNP conjugation had better antibacterial ctivity than chitosan–AuNPs, which exhibited moderate activity against S. aureus and very low activity against E. coli. Furthermore, the antibiofilm potentials of the prepared conjugates were tested against four biofilm-forming bacteria, including P. aeruginosa, B. subtilis, E. coli, and S. aureus. The obtained results indicate that the chitosan–AgNP showed a promising anti-biofilm activities on all strains, especially S. aureus, while chitosan–AuNP conjugates showed moderate anti-biofilm against B. subtilis and weak activities against the other three strains. These results showed the superiority of chitosan–AgNP as a promising antibacterial as well as biofilm formation inhibitors.

New dynamic microreactor system to mimic biofilm formation and test anti-biofilm activity of nanoparticles.

Microbial biofilms are composed of surface-adhered microorganisms enclosed in extracellular polymeric substances. The biofilm lifestyle is the intrinsic drug resistance imparted to bacterial cells protected by the matrix. So far, conventional drug susceptibility tests for biofilm are reagent and time-consuming, and most of them are in static conditions. Rapid and easy-to-use methods for biofilm formation and antibiotic activity testing need to be developed to accelerate the discovery of new antibiofilm strategies. Herein, a Lab-On-Chip (LOC) device is presented that provides optimal microenvironmental conditions closely mimicking real-life clinical biofilm status. This new device allows homogeneous attachment and immobilization of Pseudomonas aeruginosa PA01-EGFP cells, and the biofilms grown can be monitored by fluorescence microscopy. P. aeruginosa is an opportunistic pathogen known as a model for drug screening biofilm studies. The influence of flow rates on biofilms growth was analyzed by flow simulations using COMSOL® 5.2. Significant cell adhesion to the substrate and biofilm formation inside the microchannels were observed at higher flow rates > 100 µL/h. After biofilm formation, the effectiveness of silver nanoparticles (SNP), chitosan nanoparticles (CNP), and a complex of chitosan-coated silver nanoparticles (CSNP) to eradicate the biofilm under a continuous flow was explored. The most significant loss of biofilm was seen with CSNP with a 65.5% decrease in average live/dead cell signal in biofilm compared to the negative controls. Our results demonstrate that this system is a user-friendly tool for antibiofilm drug screening that could be simply applied in clinical laboratories.Key Points• A continuous-flow microreactor that mimics real-life clinical biofilm infections was developed.• The antibiofilm activity of three nano drugs was evaluated in dynamic conditions.• The highest biofilm reduction was observed with chitosan-silver nanoparticles.

In Situ Growth of Silver Nanoparticles on Chitosan Matrix for the Synthesis of Hybrid Electrospun Fibers: Analysis of Microstructural and Mechanical Properties.

A viable alternative for the next generation of wound dressings is the preparation of electrospun fibers from biodegradable polymers in combination with inorganic nanoparticles. A poly(vinyl alcohol)-chitosan-silver nanoparticles (PVA-CTS-Ag NPs) system has been developed for antimicrobial and wound healing applications. Here, the preparation of PVA-CTS-Ag electrospun fibers using a two-step process is reported in order to analyze changes in the microstructural, mechanical, and antibacterial properties and confirm their potential application in the biomedical field. The Ag nanoparticles were well-dispersed into the chitosan matrix and their cubic structure after the electrospinning process was also retained. The Ag NPs displayed an average diameter of ~33 nm into the CTS matrix, while the size increased up to 213 nm in the PVA-CTS-Ag(NPs) fibers. It was observed that strong chemical interactions exist between organic (CTS) and inorganic phases through nitrogenous groups and the oxygen of the glycosidic bonds. A defect-free morphology was obtained in the PVA-CTS-Ag NPs final fibers with an important enhancement of the mechanical properties as well as of the antibacterial activity compared with pure PVA-CTS electrospun fibers. The results of antibacterial activity against E. coli and S. aureus confirmed that PVA-CTS-Ag(NPs) fibers can be potentially used as a material for biomedical applications.