Chitosan (CS), a naturally occurring polysaccharide derived from chitin, is widely recognized for its biodegradability, biocompatibility, and non-toxicity, making it an attractive candidate for sustainable functional materials. Silver nanoparticles (AgNPs) possess remarkable antimicrobial and catalytic properties but are often produced through energy-intensive and non-ecofriendly chemical routes. In this work, we report the green synthesis of AgNPs using Rosmarinus officinalis (rosemary) extract as both a reducing and stabilizing agent, and their subsequent incorporation into CS matrices to prepare CS@R-AgNPs films via a simple ex-situ solution casting approach. The resulting nanocomposite films were comprehensively characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). TEM micrographs revealed a uniform dispersion of R-AgNPs within the CS matrix, while FTIR analysis confirmed electrostatic interactions between the polymeric chains and the nanoparticles. The CS@R-AgNPs films exhibited strong antibacterial activity against both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) strains even at a low AgNPs loading (0.5%). Moreover, the films efficiently catalyzed the reduction of 4-nitroaniline (4-NA) to 4-phenylenediamine in the presence of NaBH₄, following pseudo-first-order kinetics with rate constants increasing from 0.0871 to 0.196 min-1 as AgNPs content increased from 1% to 3%. The catalytic system demonstrated excellent stability, retaining 96% conversion after ten successive cycles. These findings underscore the potential of CS@R-AgNPs films as dual-function, environmentally benign materials for antimicrobial and catalytic applications.

Nosocomial infections caused by Staphylococcus aureus (S. aureus), a major pathogen that colonizes human skin, are a significant cause of morbidity and mortality. Effective management of S. aureus is essential, especially given the rising threat of antibiotic resistance. Innovative alternatives, such as antimicrobial peptides, are needed as they are effective against drug-resistant strains and less toxic to human cells than conventional antibiotics. Nanofiber-based materials are promising tools for delivering these peptides. In this study, a nisin-loaded polyvinyl alcohol (PVA) coated wipes were developed via electrospinning. The coated wipes were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermal gravimetric analysis (TGA). Air permeability, water sorption, and peptide assay tests were performed. Additionally, the antibacterial activity of the coated wipes was evaluated against S. aureus, including methicillin-resistant strains. The presence of nisin in the fiber was confirmed by infrared spectroscopy with the characteristic IR bands of nisin at 1652, 1517, and 1326 cm−1. The TGA results also confirmed the presence of nisin. The nisin-loaded nanofibers collected on wipes as coating exhibited significant antibacterial activity against S. aureus strains. The results indicated that the produced nanofiber-coated wipes have the potential to combat S. aureus effectively.

When a biomedical device is implanted into the body, its surface initially encounters biological fluids, resulting in the natural adsorption of various host proteins. This protein-adsorbed layer alters the inherent properties of the biomaterial surface and plays a crucial role in interactions between the implant and bacteria. Here, we investigated the influence of an adsorbed layer of albumin, the most abundant blood protein, on the adhesion and biofilm formation of three different bacterial strains: Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. We found that the effect of a serum albumin layer on bacterial adhesion was straindependent. Albumin pre-adsorption reduced the initial attachment of S. aureus and S. epidermidis to PDMS surfaces but had no impact on P. aeruginosa. However, with prolonged incubation, albumin-coated surfaces significantly promoted P. aeruginosa attachment and biofilm formation. Additionally, this biofilm alteration was associated with reduced macrophage-mediated bacterial clearance. Proteomic analysis further revealed significant physiological changes in P. aeruginosa upon exposure to albumin-coated surfaces compared to uncoated controls. These alterations were particularly associated with molecular pathways involved in surface colonization, including quorum sensing, motility, adhesion, and biofilm formation. These findings suggest that serum albumin adsorption not only affects the initial adhesion of bacteria but also modifies their adaptive responses upon contact with the biomaterial surface. This study provides a deeper understanding of the complex bacteriasurface interactions, contributing to the development of future strategies for preventing implant-associated infections.

Osteoporosis is characterized by the widespread deterioration of bone mass and microarchitecture. It poses an increasingly significant socioeconomic threat in light of the aging population. Emerging research highlights the crucial role played by crosstalk between bone cells and other components in the skeletal system, including immune cells, to maintain bone homeostasis. Despite articles introducing this novel field known as osteoimmunology, accumulating evidence has revealed that the role of the immune system in bone homeostasis extends beyond its previously recognized contributions. Therefore, we have performed a systematic review with the aim of synthesizing the existing literature on this particular topic, thereby offering readers a unified framework for immune-mediated bone regulation. A literature search was performed in PubMed, Embase and Web of Science. A total 16,021 results were found, and 150 articles were included following PRISMA guidelines. The involvement of the immune system in osteoporosis can be summarized into three primary aspects, providing a comprehensive overview for readers from diverse backgrounds: (1) the altered immune system in osteoporosis pathogenesis; (2) molecular pathways of immune system regulating bone homeostasis; and (3) current strategies targeting the immune system for therapeutic interventions. We found that the immune system not only responds to developmental changes through altered expression and differentiation but also mediates signals from other tissues to influence bone phenotype. We present a framework of osteoimmunology that can inform the development of new clinical strategies and biomaterials, highlighting immune cells as mediators of signals from other organs or tissues.

The development of effective antimicrobial surfaces is crucial for reducing the risk of medical device-associated infections. This study investigates the antibacterial potential of carvacrol (CAR), a natural essential oil, after their surface immobilization onto gold (Au) substrates through a polydopamine (pDA) layer. The successful deposition and properties of each layer were characterized using ellipsometry, water contact angle (WCA) measurements, Fourier Transform Infrared Reflection-Absorption Spectroscopy (FT-IRRAS), X-ray Photoelectron Spectroscopy (XPS), and Atomic Force Microscopy (AFM). The resulting coatings displayed a thin, uniform film with smooth topography and with enhanced hydrophilicity. Antibacterial efficacy was assessed against Staphylococcus epidermidis, a relevant etiological agent in this context. The results revealed that the polydopamine-carvacrol coated surfaces (Au-pDA-CAR) exhibited a significant reduction in bacterial viability, achieving a 96 % decrease compared to unmodified gold surfaces. This was contrasted with minimal antibacterial activity from surfaces with either only polydopamine (Au-pDA) or carvacrol (Au-CAR). Live/Dead bacterial viability assays confirmed the bactericidal effect of the Au-pDA-CAR surface, demonstrating its effectiveness in killing bacteria rather than merely preventing adhesion. Our findings indicate that the pDA-CAR coating presents a promising approach for developing antimicrobial surfaces with enhanced performance against biofilm-forming pathogens. The development of this coating is an important step towards the establishment of a new technological platform capable of preventing medical device associated infections.

Polyelectrolyte complexes (PECs) were elaborated from chitosan as cationic polymer and carboxymethylpullulan (CMP), hyaluronic acid (HA) and their derivatives grafted with aminoguaiacol (G) with different degrees of substitution (DSGA) with the aim of obtaining nanogels for drug delivery. For each couple of polysaccharides, the charge ratios giving the smaller size with the lower PDI were selected to produce PECs. CMP_CHIT and CMP-G_CHIT PECs had smaller sizes (220-280 nm) than HA_CHIT and HA-G_CHIT PECs (280-390 nm). PECs were stable at 4 degrees C during 28 days at pH 5. In phosphate buffer saline (PBS) at pH 7.4, at 4 degrees C, a better stability of PECs based on CMP-G derivatives was observed. The hydrophobic associations between aminoguaiacol groups (highlighted by measurements of pyrene fluorescence) led to a better PECs' stabilization in PBS. The PECs' antioxidant and antibacterial activities were demonstrated and related to the DSGA. Diclofenac and curcumin were used as drug models: their loading reached 260 and 53 mu g/mg PEC, respectively. The release of diclofenac in PBS at 37 degrees C followed a quasi-Fickian diffusion mechanism with release constant between 0.88 and 1.04 h-1. The curcumin release followed a slow linear increase in PBS/EtOH (60/40 V/V) with an effect of DSGA.

Using a three steps procedure a water soluble cationic bis-cyclocarbonate was prepared. Aminolysis was attempted in water but was not successful because of rapid hydrolysis of the starting cyclocarbonate in these basic conditions. Non-isocyanate polyurethanes (linear and crosslinked) were then prepared in acetonitrile with high yields. The resulting materials exhibited good thermal properties (T-deg > 230 degree celsius) and Tg > 60 degree celsius. The presence of the cationic moiety led to hydrophilic materials with swelling rate of 45% and a plastification effect was observed with Tg decreasing down to -28 degree celsius. Further, considering ammonium characteristics, antibacterial properties were assessed. Surface adhesion test showed a 99,9% inhibition towards gram-positive and gramnegative bacteria for the polyurethane thermoset. Acute toxicity was evaluated on the bis-cyclocarbonate oligomer confirming its innocuity in the studied concentration range.

AimOrthopedic implants play a tremendous role in fixing bone damages due to aging as well as fractures. However, these implants tend to get colonized by bacteria on the surface, leading to infections and subsequently prevention of healing and osteointegration. Recently, Roupie et al. showed that a nisin layer-by-layer based coating applied on biomaterials has both osteogenic and antibacterial properties. The Galleria mellonella larva is a well-known insect infection model that has been used to test the virulence of bacterial and fungal strains as well as for the high throughput screening of antimicrobial compounds against infections. Recently, we have developed an insect infection model with G. mellonella larvae to study implant-associated biofilm infections using Kirschner (K)-wires as implant material. Here, we would like to test the antibacterial capacity of nisin layer-by-layer based coatings on K-wires against Staphylococcus aureus in the G. mellonella larva implant infection model.MethodPrior to the implantation procedure, G. mellonella larvae are maintained at room temperature on wheat germ in an incubator. The larvae received bare titanium K-wires (uncoated), or either control-coated or nisin-coated K-wires. After one hour, the larvae were injected with 5×105S. aureus bacteria per larva (i.e., hematogenous implant infection model). Next, the larvae were incubated at 37oC in an incubator and the survival of the larvae was monitored for five days. Moreover, the number of bacteria on the implant surface and in the surrounding tissue was determined after 24h of incubation. Further, scanning electron microscopy (SEM) analyses were performed to study the effect of nisin on biofilm formation.ResultsThe larvae receiving the nisin-coated K-wires showed significantly higher survival rates compared to uncoated titanium K-wires, although not when compared to control-coated K-wires. A more than 1-log reduction in number of bacteria on the implant surface and in the surrounding tissue was observed in larvae receiving the nisin-coated K-wires, when compared to uncoated titanium K-wires SEM analysis showed reduced colonization of the bacteria nisin-coated K-wires compared to the controlsConclusionsIn conclusion, the antimicrobial nisin layer-by-layer based coating applied on titanium surfaces is able to prevent implant-related S. aureus biofilm infection in G. mellonella and is a promising antimicrobial strategy to prevent implant-related infections.

ObjectiveFracture-related infection (FRI) remains a major concern in orthopaedic trauma. Functionalizing implants with antibacterial coatings are a promising strategy in mitigating FRI. Numerous implant coatings have been reported but the preventive and therapeutic effects vary. This systematic review aimed to provide a comprehensive overview of current implant coating strategies to prevent and treat FRI in animal fracture and bone defect models.MethodsA literature search was performed in three databases: PubMed, Web of Science and Embase, with predetermined keywords and criteria up to 28 February 2023. Preclinical studies on implant coatings in animal fracture or defect models that assessed antibacterial and bone healing effects were included.ResultsA total of 14 studies were included in this systematic review, seven of which used fracture models and seven used defect models. Passive coatings with bacteria adhesion resistance were investigated in two studies. Active coatings with bactericidal effects were investigated in 12 studies, four of which used metal ions including Ag+ and Cu2+; five studies used antibiotics including chlorhexidine, tigecycline, vancomycin, and gentamicin sulfate; and the other three studies used natural antibacterial materials including chitosan, antimicrobial peptides, and lysostaphin. Overall, these implant coatings exhibited promising efficacy in antibacterial effects and bone formation.ConclusionAntibacterial coating strategies reduced bacterial infections in animal models and favored bone healing in vivo. Future studies of implant coatings should focus on optimal biocompatibility, antibacterial effects against multi-drug resistant bacteria and polymicrobial infections, and osseointegration and osteogenesis promotion especially in osteoporotic bone by constructing multi-functional coatings for FRI therapy.The translational potential of this paperThe clinical treatment of FRI is complex and challenging. This review summarizes novel orthopaedic implant coating strategies applied to FRI in preclinical studies, and offers a perspective on the future development of orthopaedic implant coatings, which can potentially contribute to alternative strategies in clinical practice.

Antibacterial coatings are becoming increasingly attractive for application in the field of biomaterials. In this framework, we developed polymer coating zirconia with antibacterial activity using the “grafting from” methodology. First, 1-(4-vinylbenzyl)-3-butylimidazolium chloride monomer was synthesized. Then, the surface modification of zirconia substrates was performed with this monomer via surface-initiated photo atom transfer radical polymerization for antibacterial activity. X-ray photoelectron spectroscopy, ellipsometry, static contact angle measurements, and an atomic force microscope were used to characterize the films for each step of the surface modification. The results revealed that cationic polymers could be successfully deposited on the zirconia surfaces, and the thickness of the grafted layer steadily increased with polymerization time. Finally, the antibacterial adhesion test was used to evaluate the antibacterial activity of the modified zirconia substrates, and we successfully showed the antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa strains.

Biogenic silver nanoparticles (AgNPs) have gained considerable attention in nanotechnology due to their desirable properties and potential applications. However, their long-term stability poses a bottleneck to their application. The objective of this study is to improve the stability of AgNPs using surfactants as an additional capping agent. First, biogenic AgNPs were synthesized using Salvia rosmarinus extract (R-AgNPs). Subsequently, a comprehensive characterization of their physicochemical properties and long-term stability was conducted. R-AgNPs were found to be quasi-spherical with a diameter of 31.1 ± 6.5 nm. However, despite a low zeta potential of − 34.45 ± 0.41 mV, R-AgNPs were found to be unstable after 2 weeks of storage. To improve their long-term stability, the R-AgNPs were subsequently capped using low concentrations of surfactants with varying charges: Cetyltrimethylammonium bromide (CTAB), a cationic surfactant; sodium dodecyl sulfate (SDS), an anionic surfactant; and Tween 80, a non-ionic surfactant. All surfactants were effective in stabilizing R-AgNPs, particularly using 7 µM of SDS, which significantly enhanced R-AgNP stability even after 6 months without affecting their size and morphology. Nevertheless, the addition of surfactants to R-AgNPs might affect their antibacterial activities and cause toxicity to mammalian cells. Therefore, the surfactant-stabilized R-AgNPs were evaluated against pathogenic bacteria and mammalian cells. Both R-AgNPs and surfactant R-AgNPs displayed significant antibacterial activities against Escherichia coli , Pseudomonas aeruginosa , Staphylococcus aureus , and Enterococcus faecalis . Moreover, an eightfold increase in antibacterial activity against S. aureus was achieved CTAB-stabilized R-AgNPs at 3 µM of CTAB. Importantly, both R-AgNPs and surfactant-stabilized R-AgNPs showed no cytotoxic effects against mouse fibroblasts at concentrations effective against all the tested bacteria.

The use of chitosan as a support in the field of catalysis has gained tremendous interest because of its abundance and sustainability. We herein disclose a straightforward strategy to trap and stabilize bismuth nanoparticles (BiNPs) on chitosan biopolymer Bi@CS and their use for catalytic applications. Bi@CS was configured as micrometer-thick films, porous beads, and native powders analyzed and next used for the controlled and selective reduction of nitroaromatic compounds to their corresponding anilines and azoarenes, respectively, by varying the concentration medium in reducing NaBH4. A regioselective mechanism has been suggested. Powder nanocomposites CSp-BiNPs exhibited high catalytic capacity, and 10 corresponding anilines and 15 azoarenes were obtained with very high yields. The reductions were achieved under mild and sustainable reaction conditions (water solvent and room temperature) with easy processing and 12 recovery cycles. Shaped catalysts were easily recovered by simple filtration. This catalyst, derived from nontoxic and affordable bismuth metal supported on chitosan ocean waste, presents significant improvements in the realm of sustainable chemistry and could open a new channel of possibilities for green catalysis.

Nowadays, there is an increasing need to develop new green biodegradable materials for active antimicrobial food packaging applications. In this work, polylactic acid-2 % Fluorphlogopite-1.5%silver nanoparticles (AgNPs) composites were prepared using melt extrusion. Films were characterized using Scanning Electron Microscopy, Transmission Electron Microscopy, X-Ray Diffraction, Differential Scanning Calorimetry, and Water Contact Angle measurements. Results showed a good dispersion of both fluorphlogopite and AgNPs in PLA which increased the surface roughness and hydrophobicity of PLA. Subsequently, the thermal, mechanical, and barrier properties of PLA nanocomposites were assessed. PLA-2%Fluorphlogopite-1.5%AgNPs showed a higher thermal stability than neat PLA while the mechanical properties remained unchanged. Furthermore, the excellent barrier properties of PLA were also unaffected by the introduction of fluorphlogopite and AgNPs. Finally, the antibacterial activity of the nanocomposites was assessed against three bacteria, S. aureus, E. faecalis, and E. coli and PLA-2%Fluorphlogopite-1.5%AgNPs inhibited almost completely the bacterial adhesion on the surface of the films.

One of the main challenges when building antibacterial surfaces with antimicrobial peptides (AMPs) is to preserve their antimicrobial activity after stable immobilization of the peptides. Among all parameters, order/conformation of self-assembled monolayers, used as spacer, is one the most important. Herein we report the covalent immobilization of the nisin Z peptide on a gold surface functionalized with a self-assembled monolayer of 11-mercaptoundecanoic acid (MUA) alone or mixed with 6-mercaptohexanol, used as a spacer. The MUA acid is activated by treatment with carbodiimide/N-hydroxysuccinimidine and then reacts with nisin Z to form amide bonds via the N terminal part of the peptide. We have characterized each step of the surface modification using X-ray photoelectron spectroscopy, FTIR-ATR spectroscopy and contact angle measurements. The combined results show the success of each functionalization step. Additionally, SFG brings information on the orientation and conformational ordering of the self-assembled monolayers. Indeed, a better order of MUA25 layers compared to MUA was observed due to the spacing of carboxylic acid groups. The antibacterial activity of the immobilized AMPs against Staphylococcus aureus is evaluated using confocal microscopy and bacterial counting: it increases with a better order of the SAMs rather than a greater peptide concentration. This study provides fundamental insights on how to engineer AMPs and substrate to produce efficient biocidal surfaces.

Zirconia surfaces were functionalized by polymer grafting according to a simple and successful two-steps procedure. In the first step, the initiator bearing a N,N-dimethyl amine group was grafted on the surface by co-deposition with dopamine. Secondly, different monomers such as styrene, methyl methacrylate, 2-hydroxyethylmethacrylate, 2,2,2-trifluoroethyl methacrylate and styrene sulfonate were polymerized on the surface using photochemical activation. The efficiency of the two steps, initiator grafting and photopolymerization, were checked by several analytical techniques including X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE) and water contact angle measurements. Theses characterizations highlighted the surface chemical change after each step and the possibility to modulate surface hydrophilicity and hydrophobicity by grafting-from polymerizations.

N-[2-(acryloyloxy)ethyl]-N,N-dimethyl-N-butylammonium iodide was successfully photo-polymerized from native and thiolated PDMS surface, in the presence of benzophenone. The directly and indirectly grafted surfaces exhibited quaternary ammonium densities of about 1015 and 1017 N+.cm−2, respectively, and very high hydrophilicity compared to non-grafted surfaces. The live and dead tests performed by fluorescence microscopy revealed an effective contact bactericidal effect of this surface against Escherichia coli and Staphylococcus epidermidis.

Several clay minerals as inorganic fillers were incorporated to aliphatic polyester by various procedures. The target of enhancing the physicochemical properties of the resulting composite material leading thereby to overcome the limitations of neat polyesters. Still, bentonite (Bnt) as a clay mineral has been relatively unexplored as a reinforcing agent of the poly(epsilon-caprolactone) (PCL). In this study, a bio-nanocomposite based on poly (epsilon-caprolactone) & bentonite nanofiller was prepared by in-situ ring opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL) under open air using tin-based catalyst. The obtained bio-composites (PCL-OBnt) were fully characterized to examine their structural interactions, thermal stability, mechanical, and morphological properties. Finally, the antimicrobial activity against S. epidermidis and S. aureus of the prepared bio-composites materials was evaluated.

Implanted biomaterials can be regarded in a cornerstone in the domain of bone surgery. Their surfaces are expected to fulfil two particular requirements: preventing the settlement and the development of bacteria, and stimulating bone cells in view to foster osseointegration. Therefore, a modern approach consists in the design of dual functional coatings with both antibacterial and osteogenic features. To this end, we developed ultrathin Layer-by-Layer (LbL) coatings composed of biocompatible polyelectrolytes, namely chondroitin sulfate A (CSA) and poly-l-lysine (PLL). The coatings were crosslinked with genipin (GnP), a natural and biocompatible crosslinking agent, to increase their resistance against environmental changes, and to confer them adequate mechanical properties with regards to bone cell behaviors. Antibacterial activity was obtained with nisin Z, an antimicrobial peptide (AMP), which is active against gram-positive bacteria. The coatings had a significant bactericidal impact upon Staphylococcus aureus, with fully maintained bone cell adhesion, proliferation and osteogenic differentiation.

Vinylbenzyl dimethylbutylammonium chloride was successfully grafted and photo-polymerized from a PDMS surface, in presence of benzophenone. The obtained surface exhibited quaternary ammonium density above 10(17) charge/cm(2) and very high hydmphilicity compared to ungrafted surfaces. Bacterial enumeration and fluorescence microscopy revealed an efficient contact killing of this surface against Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis.

Cationic ROMP-polymers bearing ammonium or phosphonium groups were photo-grafted onto a PDMS surface via the thiol-ene click reaction, in the presence of benzophenone. The PDMS surface was first thiolated using pentaerythritol tetrakis (3-mercaptopropionate) (PTTMP) under UV, in the presence of benzophenone. The obtained cationic surfaces exhibited charge densities above 1014 charge/cm2 and a higher degree of hydrophilicity compared to non-grafted surfaces. The live and dead tests performed by fluorescence microscopy revealed an effective contact bactericidal effect of these surfaces against Escherichia coli and Staphylococcus epidermidis.