Silver nanoparticle and lysozyme/tannic acid layer-by-layer assembly antimicrobial multilayer on magnetic nanoparticle by an eco-friendly route

Exploring the Efficacy of pH-Responsive Vancomycin/Ag/ZIF-8 Nanoparticles Modified with Hyaluronic Acid for Enhanced Antibacterial Therapy and Wound Healing

This study introduces a novel type of metal-organic framework material, specifically zeolitic imidazolate framework-8 (ZIF-8), that is integrated with silver nanoparticles and further enhanced by incorporating vancomycin (Van) to create a composite named as Van/Ag/ZIF-8. This composite demonstrates a potent and smart antimicrobial effect due to its ability for releasing silver ions and Van in a controlled manner, especially in the microacidic conditions surrounding bacterial cells. Furthermore, we used hyaluronic acid to modify Van/Ag/ZIF-8, resulting in a composite denoted as Van/Ag/ZIF-8@HA. This composite exhibits a significant inhibition effect against the proliferation of both Gram-negative (Escherichia coli 100%) and Gram-positive (Staphylococcus aureus 99.9%) resistant bacterial strains while exerting no adverse effects on animal cellular growth. These findings underscore its favorable biocompatibility profile. The experimental results show a combined antibacterial action against prevalent bacterial infections, which is supported by in vivo experiments using a skin wound model. This work confirms the composite's significant role in fighting pathogenic infections and aiding in healing skin wounds. The innovative strategy not only tackles the pressing issue of antibiotic-resistant bacterial infections but also marks a significant advancement in the areas of wound healing and medical research, offering a promising path for future investigations and therapeutic uses.

Improving antifouling performance of FO membrane by surface immobilization of silver nanoparticles based on a tannic acid: diethylenetriamine precursor layer for municipal wastewater treatment

In this study, a facile method for multifunctional surface modification on forward osmosis (FO) membrane was constructed by surface immobilization of AgNPs based on tannic acid (TA)/diethylenetriamine (DETA) precursor layer. The cellulose triacetate (CTA) FO membranes modified by TA and DETA with different co-deposition time (6 h, 12 h, 24 h) were investigated. Results indicated that the TA/DETA (24)-Ag CTA membrane with a TA/DETA co-deposition time of 24 h was identified to be optimal, which attained more hydrophilic. And it had the bacterial mortality of Escherichia coli and Staphylococcus aureus reaching 98.23% and 99.83% respectively and possessed excellent physical and chemical binding stability. Meanwhile, the coating layer resulted in the antifouling ability without damaging the membrane intrinsic transport characteristics. As for synthetic municipal wastewater treatment, the water flux of CTA FO membrane decreased approximately 49% of the initial flux after running for 14 days. In contrast, the flux decline rate of TA/DETA (24)-Ag CTA membrane was about 37%. Furthermore, less foulant deposition and higher recovery rate of water flux was observed for TA/DETA (24)-Ag CTA membrane, implying that the modified membrane effectively alleviated membrane fouling and processed a lower flux decline during municipal wastewater treatment. It was attributed to the enhanced surface hydrophilicity and antibacterial property of the coating layer, which improved antifouling property.

Developing a Novel Enamel Adhesive with Amorphous Calcium Phosphate and Silver Nanoparticles to Prevent Demineralization during Orthodontic Treatment

During fixed orthodontic treatment, white spot lesions are prevalent issues associated with cariogenic bacteria. This study aims to construct an orthodontic adhesive containing nanoparticles of amorphous calcium phosphate-polydopamine-Ag (NPA) fillers to combat white spot lesions. The NPA fillers were prepared and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The biocompatibility of the fillers was evaluated. A colony counting test evaluated the antibacterial property of the fillers against Streptococcus mutans (S. mutans). NPA fillers were mixed with orthodontic adhesive (Transbond XT) at different weight ratios (0, 0.1, 0.2, 0.3, and 0.5 wt.%). The shear bond strength and antibacterial properties were then further investigated. The results showed that NPA was prepared successfully, with good antibacterial properties. The cell survival rate of all groups of fillers was higher than 70%, showing good biocompatibility. Moreover, the shear bond strength of the orthodontic adhesive with 0.2 wt.% NPA fillers was 11.89 ± 1.27 MPa, meeting the minimal clinical bond strength requirements of 7.8 MPa. Furthermore, the orthodontic adhesive resin blocks and the extract displayed good antibacterial properties, with the number of colonies decreasing significantly (p < 0.001). Taken together, we think that an orthodontic adhesive with NPA may have a good application potential for the prevention and treatment of white spot lesions.

pH-responsive Ag-Phy@ZIF-8 nanoparticles modified by hyaluronate for efficient synergistic bacteria disinfection

Zeolitic imidazolate framework-8 (ZIF-8) is a type of Metal-organic frameworks (MOFs), which shows promising application in the field of bacterial infection, owing to its excellent biocompatibility. Here, we report the encapsulation of silver nanoparticles (Ag NPs) in ZIF-8, accompanied with embedding of physcion (Phy) to obtain Ag-Phy@ZIF-8 with efficient and intelligent synergistic antimicrobial capabilities. Due to the micro-acidic environment around the bacteria, the release of silver and Phy shows a controlled released. Further, the Ag-Phy@ZIF-8 is modified by hyaluronate (HA), denoted as Ag-Phy@ZIF-8@HA, which has a strong inhibitory effect on the growth of both E. coli (99.1%) and S. aureus (99.5%), with no impacting on cell growth, showing good biocompatibility. Thus, these pH-responsive biocomposites have the potential application on smart wound excipients for bacterial infections.

Characterization of Collagen/Beta Glucan Hydrogels Crosslinked with Tannic Acid

Hydrogels based on collagen/β-glucan crosslinked with tannic acid were obtained by neutralization using dialysis. The presence of tannic acid allowed obtaining stable hydrogel materials with better mechanical properties. Tannic acid was released from matrices gradually and not rapidly. The antioxidant properties of the obtained hydrogels increased over the course of their incubation in culture media and were dependent on the concentration of tannic acid in the matrices. The obtained materials influenced dehydrogenase activity and the ATP level of pathogens. Additionally, the materials' extracts improved the HaCaT cells' viability. Therefore, the obtained hydrogels seem to be promising biocompatible materials which display antimicrobial properties.

Enhanced Antibacterial Activity of CuS-BSA/Lysozyme under Near Infrared Light Irradiation

The synthesis of multifunctional photothermal nanoagents for antibiotic loading and release remains a challenging task in nanomedicine. Herein, we investigated a simple, low-cost strategy for the preparation of CuS-BSA nanoparticles (NPs) loaded with a natural enzyme, lysozyme, as an antibacterial drug model under physiological conditions. The successful development of CuS-BSA NPs was confirmed by various characterization tools such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Lysozyme loading onto CuS-BSA NPs was evaluated by UV/vis absorption spectroscopy, Fourier-transform infrared spectroscopy (FTIR), zeta potential, and dynamic light scattering measurements. The CuS-BSA/lysozyme nanocomposite was investigated as an effective means for bacterial elimination of B. subtilis (Gram-positive) and E. coli (Gram-negative), owing to the combined photothermal heating performance of CuS-BSA and lysozyme release under 980 nm (0.7 W cm-2) illumination, which enhances the antibiotic action of the enzyme. Besides the photothermal properties, CuS-BSA/lysozyme nanocomposite possesses photodynamic activity induced by NIR illumination, which further improves its bacterial killing efficiency. The biocompatibility of CuS-BSA and CuS-BSA/Lysozyme was elicited in vitro on HeLa and U-87 MG cancer cell lines, and immortalized human hepatocyte (IHH) cell line. Considering these advantages, CuS-BSA NPs can be used as a suitable drug carrier and hold promise to overcome the limitations of traditional antibiotic therapy.

In Vitro Microbiological and Drug Release of Silver/Ibuprofen Loaded Wound Dressing Designed for the Treatment of Chronically Infected Painful Wounds

This study consisted of developing a dressing loaded with silver (Ag) and ibuprofen (IBU) that provides a dual therapy, antibacterial and antalgic, intended for infected painful wounds. Therefore, non-woven polyethyleneterephtalate (PET) textiles nonwovens were pre-treated by cyclodextrin crosslinked with citric acid by a pad/dry/cure process. Then, textiles were impregnated in silver solution followed by a thermal treatment and were then coated by Layer-by-Layer (L-b-L) deposition of a polyelectrolyte multilayer (PEM) system consisting of anionic water-soluble poly(betacyclodextrin citrate) (PCD) and cationic chitosan. Finally, ibuprofen lysinate (IBU-L) was loaded on the PEM coating. We demonstrated the complexation of IBU with native βCD and PCD by phase solubility diagram and ¹H NMR. PEM system allowed complete IBU-L release in 6 h in PBS pH 7.4 batch (USP IV). On the other hand, microbiological tests demonstrated that loaded silver induced bacterial reduction of 4 Log₁₀ against S. aureus and E. coli and tests revealed that ibuprofen lysinate loading did not interfere with the antibacterial properties of the dressing.

Single-Step Green Synthesis of Highly Concentrated and Stable Colloidal Dispersion of Core-Shell Silver Nanoparticles and Their Antimicrobial and Ultra-High Catalytic Properties

The versatile one-pot green synthesis of a highly concentrated and stable colloidal dispersion of silver nanoparticles (Ag NPs) was carried out using the self-assembled tannic acid without using any other hazardous chemicals. Tannic acid (Plant-based polyphenol) was used as a reducing and stabilizing agent for silver nitrate in a mild alkaline condition. The synthesized Ag NPs were characterized for their concentration, capping, size distribution, and shape. The experimental results confirmed the successful synthesis of nearly spherical and highly concentrated (2281 ppm) Ag NPs, capped with poly-tannic acid (Ag NPs-PTA). The average particle size of Ag NPs-PTA was found to be 9.90 ± 1.60 nm. The colloidal dispersion of synthesized nanoparticles was observed to be stable for more than 15 months in the ambient environment (25 °C, 65% relative humidity). The synthesized AgNPs-PTA showed an effective antimicrobial activity against Staphylococcus Aureus (ZOI 3.0 mM) and Escherichia coli (ZOI 3.5 mM). Ag NPs-PTA also exhibited enhanced catalytic properties. It reduces 4-nitrophenol into 4-aminophenol in the presence of NaBH₄ with a normalized rate constant (K_nor = K/m) of 615.04 mL·s^-1·mg^-1. For comparison, bare Ag NPs show catalytic activity with a normalized rate constant of 139.78 mL·s^-1·mg^-1. Furthermore, AgNPs-PTA were stable for more than 15 months under ambient conditions. The ultra-high catalytic and good antimicrobial properties can be attributed to the fine size and good aqueous stability of Ag NPs-PTA. The unique core-shell structure and ease of synthesis render the synthesized nanoparticles superior to others, with potential for large-scale applications, especially in the field of catalysis and medical.

Polyurethane/Nanosilver-Doped Halloysite Nanocomposites: Thermal, Mechanical Properties, and Antibacterial Properties

In this study, the researchers successfully embellished the surface of halloysite (Ag/HNTs) with silver using halloysite, silver nitrate (AgNO₃), and polyvinylpyrrolidone (PVP). The researchers then prepared polyurethane that contained pyridine ring by using 4,4′-diphenylmethane diisocyanate (MDI) and polytetramethylene glycol (PTMG) as the hard chain segment and the soft chain segment of polyurethane (PU), as well as 2,6-pyridinedimethanol (2,6-PDM) as the chain extension agent. This was followed by the preparation of Ag/HNTs/PUs nanocomposite thin films, achieved by mixing Ag/HNTs with different ratios into polyurethane that contains pyridine ring. First, the Ag/HNTs powders were analyzed using energy-dispersive X-ray spectroscopy, X-ray diffraction, and transmission electron microscopy. Subsequently, Fourier-transform infrared spectroscopy was used to examine the dispersibility of Ag/HNTs in PU, whereas the thermal stability and the viscoelasticity of Ag/HNTs/PU were examined using thermal gravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. When the mechanical properties of Ag/HNTs/PU were tested using a universal strength tester, the results indicated a maximum increase of 109.5% in tensile strength. The researchers then examined the surface roughness and the hydrophobic ability of the Ag/HNTs/PU thin films by using atomic force microscopy and water contact angle. Lastly, antibacterial testing on Escherichia coli revealed that when the additive of Ag/HNTs reached 2.0 wt%, 99.3% of the E. coli were eliminated. These results indicated that the addition of Ag/HNTs into PU could enhance the thermal stability, mechanical properties, and antibacterial properties of PU, implying the potential of Ag/HNTs-02 as biomedicine material.

Medical Applications Based on Supramolecular Self-Assembled Materials From Tannic Acid

Polyphenol, characterized by various phenolic rings in the chemical structure and an abundance in nature, can be extracted from vegetables, grains, chocolates, fruits, tea, legumes, and seeds, among other sources. Tannic acid (TA), a classical polyphenol with a specific chemical structure, has been widely used in biomedicine because of its outstanding biocompatibility and antibacterial and antioxidant properties. TA has tunable interactions with various materials that are widely distributed in the body, such as proteins, polysaccharides, and glycoproteins, through multimodes including hydrogen bonding, hydrophobic interactions, and charge interactions, assisting TA as important building blocks in the supramolecular self-assembled materials. This review summarizes the recent immense progress in supramolecular self-assembled materials using TA as building blocks to generate different materials such as hydrogels, nanoparticles/microparticles, hollow capsules, and coating films, with enormous potential medical applications including drug delivery, tumor diagnosis and treatment, bone tissue engineering, biofunctional membrane material, and the treatment of certain diseases. Furthermore, we discuss the challenges and developmental prospects of supramolecular self-assembly nanomaterials based on TA.

Effective detection of bacteria using metal nanoclusters

Antibiotic-resistant bacterial infections cause more than 700 000 deaths each year worldwide. Detection of bacteria is critical in limiting infection-based damage. Nanomaterials provide promising sensing platforms owing to their ability to access new interaction modalities. Nanoclusters feature sizes smaller than traditional nanomaterials, providing great sensitive ability for detecting analytes. The distinct optical and catalytic properties of nanoclusters combined with their biocompatibility enables them as efficient biosensors. In this review, we summarize multiple strategies that utilize nanoclusters for detection of pathogenic bacteria.

Nanoparticles at biointerfaces: Antibacterial activity and nanotoxicology

Development of a biomaterial that is resistant to the adhesion and consequential proliferation of bacteria, represents a significant challenge in terms of application of such materials in various aspects of health care. Over recent years a large number of synthetic methods have appeared with the overall goal of the prevention of bacterial adhesion to surfaces. In contrast to these artificial techniques, living organisms over millions of years have developed different systems to prevent the colonization of microorganisms. Recently, these natural approaches, which are based on surface nanotopography, have been mimicked to fabricate a modern antibacterial surface. In this vein, use of nanoparticle (NP) technology has been explored in order to create a suitable antibacterial surface. However, few studies have focused on the toxicity of these techniques and the ecotoxicity of NP materials on mammalian and bacterial cells simultaneously. Researchers have observed that the majority of previous studies have demonstrated some of the extents of the harmful impacts on mammalian cells. Here, we provide a critical review of the NP approach to antibacterial surface treatment, and also summarize the studies of toxic effects caused by metal NPs on bacteria and mammalian cells.

Multifunctional Tannic Acid (TA) and Lysozyme (Lys) Films Built Layer by Layer for Potential Application on Implant Coating

A multifunctional (TA/Lys)_n film, featuring good antioxidant property, fast cell attachment at the initial stage, enhanced osteogenesis, and broad-spectrum antibacterial property, was constructed by the layer-by-layer (LBL) method. The building process was monitored by quartz crystal microbalance with dissipation (QCM-D); the physical properties, such as topography, stiffness in dry and liquid state, and conformation of Lys in the film, were thoroughly characterized. These physical properties were modulated by varying the salt concentration at which the film was constructed. The film not only allows for favorable cell attachment and proliferation of preosteoblasts Mc3t3-E1 but also provides antibacterial property against Gram-positive bacteria, S. aureus and M. lysodeikticus, and Gram-negative bacteria, E. coli. It also displays good antioxidant property, which plays a critical role on fast cell attachment at the initial stage.

In situ synthesis, stabilization and activity of protein-modified gold nanoparticles for biological applications

We demonstrate an in situ synthesis, stabilization and activity of a nanoparticle-based protein carrier platform via the Layer-by-Layer (LbL) technology.

Microenvironment-Responsive Magnetic Nanocomposites Based on Silver Nanoparticles/Gentamicin for Enhanced Biofilm Disruption by Magnetic Field

Biofilms contribute to persistent bacterial infections as well as formidable resistances to conventional antibiotics. However, it is still a major challenge to establish an advanced antibacterial nanoplatform that can efficiently eradicate biofilms while overcoming bacterial resistances. Taking advantage of the stimuli-responsive technique and the magnetic guidance strategy, here we present a highly efficient nanoplatform for planktonic inactivation and biofilm disruption. The multilayer films consisting of antibiotic gentamicin (Gen), tannic acid, and silver nanoparticles (AgNPs) were fabricated and coated on magnetic nanoparticles via electrostatic interactions. To achieve controlled drug release and improved biocompatibility, biodegradable hyaluronic acid was capped on the outer surface as a responsive shell. In vitro release profiles suggested that the nanocomposites showed both enzyme and pH-responsive release properties. The nanoplatform could be employed as a powerful nanocarrier for small molecular Gen and AgNPs delivery and on-demand release in response to bacterial infection microenvironment. The nanocomposites also showed satisfying antibacterial capacities against planktonic Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Intriguingly, with magnetic field navigation (NdFeB, 2000 gauss), the nanocomposites could be guided to handily penetrate into S. aureus biofilm and performed dual-responsive release, showing significantly enhanced biofilm disruption. Moreover, excess reactive oxygen species production resulting from the nanocomposites contributed to the decomposition of biofilm matrix and ultimate biofilm eradication. As a consequence, the ingenious antibacterial nanoplatform could be promising for combating biofilm infections while overcoming bacterial resistances with extra environmental factors such as magnetic field.

Tailored antimicrobial activity and long-term cytocompatibility of plasma polymer silver nanocomposites

The deposition of coatings enabling antibacterial properties in combination with cytocompatibility remains a challenge for biomaterial applications, such as in medical devices. Silver is one of the most utilized antibacterial surface components, due to its efficacy and extensive applicability. In this work, silver-containing plasma polymer nanocomposites (single layer and multilayers) were developed and tested, with a focus on cytotoxicity and bactericidal function, on the NIH3T3 mammalian cell line as well as Gram-negative ( Pseudomonas aeruginosa) and Gram-positive ( Staphylococcus aureus) bacterial strains. The data demonstrate that a tuneable Ag⁺ release is required, allowing sufficient antimicrobial activity while retaining appropriate cytocompatibility over the entire testing period of up to eight days.

Polyphenols at interfaces

Polyphenols are important molecules in living organisms, particularly in plants, where they serve as protectants against predators. They are also of fundamental importance in pharmacology for their antioxidant and antibacterial activities. Since a few years polyphenols are also used in surface functionalization mimicking the tannin deposition observed when tea or red wine are in contact with the surface of cups or glasses respectively. The interaction of polyphenols with proteins to yield colloids and of polyphenol with surfaces will be reviewed in this article to provide an overview of such particles and surface functionalization methods in modern surface science. Particular emphasis will be given to biological applications of polyphenols at interfaces.

Layer-By-Layer Decorated Nanoparticles with Tunable Antibacterial and Antibiofilm Properties against Both Gram-Positive and Gram-Negative Bacteria

Bacteria-mediated diseases are a global healthcare concern due to the development and spread of antibiotic-resistant strains. Cationic compounds are considered membrane active biocidal agents having a great potential to control bacterial infections, while limiting the emergence of drug resistance. Herein, the versatile and simple layer-by-layer (LbL) technique is used to coat alternating multilayers of an antibacterial aminocellulose conjugate and the biocompatible hyaluronic acid on biocompatible polymer nanoparticles (NPs), taking advantage of the nanosize of these otherwise biologically inert templates. Stable polyelectrolyte-decorated particles with an average size of 50 nm and ζ potential of +40.6 mV were developed after five LbL assembly cycles. The antibacterial activity of these NPs against the Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli increased significantly when the polycationic aminocellulose was in the outermost layer. The large number of amino groups available on the particle surface, together with the nanosize of the multilayer conjugates, improved their interaction with bacterial membrane phospholipids, leading to membrane disruption, as confirmed by a Langmuir monolayer model, and the 10 logs reduction for both bacteria. The biopolymer decorated NPs were also able to inhibit the biofilm formation of S. aureus and E. coli by 94 and 40%, respectively, without affecting human cell viability. The use of LbL-coated NPs appears to be a promising antibiotic-free alternative for controlling bacterial infections using a low amount of antimicrobial agent.