Antibacterial and biocompatible surfaces based on dopamine autooxidized silver nanoparticles

AgNPs-Modified Polylactic Acid Microneedles: Preparation and In Vivo/In Vitro Antimicrobial Studies

OBJECTIVE

To prepare polylactic acid microneedles (PLAMNs) with sustained antibacterial effect to avoid skin infection caused by traditional MNs-based biosensors.

METHODS

Silver nanoparticles (AgNPs) were synthesized using an in-situ reduction process with polydopamine (PDA). PLAMNs were fabricated using the hot-melt method. A series of pressure tests and puncture experiments were conducted to confirm the physicochemical properties of PLAMNs. Then AgNPs were modified on the surface of PLAMNs through in-situ reduction of PDA, resulting in the formation of PLAMNs@PDA-AgNPs. The in vitro antibacterial efficacy of PLAMNs@PDA-AgNPs was evaluated using agar diffusion assays and bacterial liquid co-culture approach. Wound healing and simulated long-term application were performed to assess the in vivo antibacterial effectiveness of PLAMNs@PDA-AgNPs.

RESULTS

The MNs array comprised 169 tiny needle tips in pyramidal rows. Strength and puncture tests confirmed a 100% puncture success rate for PLAMNs on isolated rat skin and tin foil. SEM analysis revealed the integrity of PLAMNs@PDA-AgNPs with the formation of new surface substances. EDS analysis indicated the presence of silver elements on the surface of PLAMNs@PDA-AgNPs, with a content of 14.44%. Transepidermal water loss (TEWL) testing demonstrated the rapid healing of micro-pores created by PLAMNs@PDA-AgNPs, indicating their safety. Both in vitro and in vivo tests confirmed antibacterial efficacy of PLAMNs@PDA-AgNPs.

CONCLUSIONS

In conclusion, the sustained antibacterial activity exhibited by PLAMNs@PDA-AgNPs offers a promising solution for addressing skin infections associated with MN applications, especially when compared to traditional MN-based biosensors. This advancement offers significant potential for the field of MN technology.

Homogeneous silver nanoparticle loaded polydopamine/polyethyleneimine-coated bacterial cellulose nanofibers for wound dressing

Utilizing mussel-inspired chemistry is an advanced strategy for surface modification, because dopamine (DA) can form a material-independent adhesive coating and further functionalization can be achieved, including the production of silver nanoparticles (AgNPs). Nevertheless, DA easily aggregates in the nanofiber network structure of bacterial cellulose (BC), which not only blocks the pores in the BC structure but also leads to the formation of large silver particles and the burst release of highly cytotoxic silver ions. Herein, a homogeneous AgNP-loaded polydopamine (PDA)/polyethyleneimine (PEI) coated BC was constructed via a Michael reaction between PDA and PEI. Under the action of PEI, the PDA/PEI coating was uniformly attached to the BC fiber surface with a thickness of approximately 4 nm, and homogeneous AgNPs were produced on the uniform PDA/PEI/BC (PPBC) fiber surface. The sustained release of silver ions was better from AgNPs@PPBC than from AgNPs@PDA/BC. The obtained AgNPs@PPBC exhibited excellent antibacterial activities and cytocompatibility. The results of the in vivo assay indicated that the AgNPs@PPBC dressing could inhibit S. aureus infection and inflammation, promote hair follicle growth, enhance collagen deposition, and accelerate wound healing within 12 days compared with BC. These results illustrate that the homogeneous AgNPs@PPBC dressing has great potential for treating infected wounds.

Polydopamine, harness of the antibacterial potentials-A review

Antibiotic resistance is one of the major causes of morbidity and mortality, triggered by the adhesion of microbes and to some extent the formation of biofilms. This condition has been quite challenging in the health and industrial sector. Conditions and processes required to foil these infectious and resistance are of much concern. The synthesis of PDA material, inspired by the Mytilus edulis foot protein (MEFP)5 possesses unique characteristics that allow for, adhesion, photothermal therapy, synergistic effects with other materials, biocompatibility process, etc. Therefore, their usage holds great potential for dealing with both the infectious nature and the antibiotic resistance processes. Hence, this review provides an overview of the mechanism involved in accomplishing and eradicating bacteria, the recently harnessed antibacterial effect of the PDA through other properties they possess, a way forward in tapping the benefit embedded in the PDA, and the future perspective.

Mussel-inspired antimicrobial coating on PTFE barrier membranes for guided tissue regeneration

Guided tissue regeneration procedures to treat periodontitis lesions making use of polytetrafluoroethylene (PTFE) membranes exhibit large variability in their surgical outcomes, due to bacterial infection following implantation. This work reports on a facile method to obtain antimicrobial coatings for such PTFE membranes, by exploiting a mussel-inspired approach andin-situformation of silver nanoparticles (AgNPs). PTFE films were initially coated with self-polymerized 3,4-dihydroxy-DL-phenylalanine (DOPA) (PTFE-DOPA), then incubated with AgNO₃solution. In the presence of catechol moieties, Ag⁺ions reduced into Ag⁰, forming AgNPs of around 68 nm in the polyDOPA coating on PTFE membranes (PTFE-DOPA-Ag). The x-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy analyses indicated that the AgNPs were distributed quite homogeneously in the polymeric membrane. The antimicrobial ability of PTFE-DOPA-Ag membranes againstStaphylococcus aureusandEscherichia coliwas assessed.In vitrocell assay using NIH 3T3 fibroblasts showed that, although cells were adhered to PTFE-DOPA-Ag membranes, their viability and proliferation were limited demonstrating again the antibacterial activities of PTFE-DOPA-Ag membranes. This work provides proof-of-concept study of a new versatile approach for AgNPs coating, which may be easily applied to many other types of polymeric or metallic implants through exploiting the adhesive behavior of mussel-inspired coatings.

Silver nanoparticles functionalized Paclitaxel nanocrystals enhance overall anti-cancer effect on human cancer cells

For chemotherapeutic drugs, precise tumor-targeting and high anti-cancer efficiency is equally important in order to enhance chemotherapy and reverse drug resistance. The combination of multifunctional agents to achieve synergy should be a promising strategy. In our study, we have successfully developed novel multifunctionalized drug nanocrystals to realize co-delivery of the organic drug Paclitaxel (PTX), inorganic silver nanoparticles (AgNPs) and a tumor targeting agent. To be specific, PTX nanocrystals were first prepared as a template, then coated with polydopamine (PDA). The PDA layer was utilized as the connection bridge to produce and deposit AgNPs in situ, and provide sites for tumor-targeting peptide NR1 (RGDARF) grafting. As a result, these NR1/AgNP-decorated drug nanocrystals exhibited dramatically improved cellular uptake efficiency, in vitro anti-cancer activity and an anti-migratory effect against a variety of cancer cells, which was attributable to the synergistic, or at least additive, effect of the AgNPs and PTX, enhanced cellular uptake efficiency through NR1-receptor interaction, pH-responsive drug release and the nanoscaled nature. In particular, high anti-cancer activity and low side effects from these NR1/AgNP-decorated PTX nanocrystals were well balanced in terms of good selectivity and biocompatibility. Moreover, these novel drug nanocrystals displayed strong apoptotic-inducing potency, resulting in cell membrane lysis, nuclear damage, mitochondria dysfunction, excessive ROS release and double-stranded DNA breakage. The potential acting mechanism and molecular basis of these novel drug nanocrystals is relevant to the regulation of mitochondria-mediated apoptosis with a greater Bax-to-Bcl-2 ratio and the activation of pro-apoptotic P53 and caspase 3.

Metallic Nanoparticle-Decorated Polydopamine Thin Films and Their Cell Proliferation Characteristics

Plasmonic metal nanoparticle (NP)-decorated thin films of biobased and biocompatible polymers provide significant opportunities in various biomedical applications. Inspired from the adhesive proteins of the marine mussels, polydopamine (PDA) serves as a versatile, biocompatible, and simple thin-film material and enhances cell growth and proliferation. Herein, we report the fabrication of the gold NPs (AuNPs) or silver NPs (AgNPs)-deposited thin films of PDA and their employment in cell growth and proliferation. PDA thin film with its numerous functional groups enabled well-controlled adsorption of NPs. The number density of NPs was manipulated simply by tuning the deposition time. Cell viability test for human lung cancer (A549) and human colon cancer (CaCO2) cell lines indicated that a thin layer of PDA film remarkably enhanced the cell growth and proliferation. The lower number density of NPs for the 24 h of the culture time resulted in a higher proliferation rate. However, the increase in both the number density of NPs and culture time led to a decrease in cell growth.

A novel CPC composite cement reinforced by dopamine coated SCPP fibers with improved physicochemical and biological properties

Traditional CPC cements have attracted wide attentions in repairing bone defects for injectability, easy plasticity and good osseointegration. However, its further application was limited by poor mechanical properties, long setting time and unsatisfactory biocompatibility. To solve these problems, polydopamine (DOPA) coated strontium-doped calcium polyphosphate (SCPP) fibers were added into CPC cements for the first time. A doping amount at fiber weight fraction of 0%, 1%, 2% and 5% was designed to develop a multifunctional composite fitting for bone tissues' regeneration and reconstruction and the optimum amount was selected through subsequent physicochemical and biological characterizations. The results implied DOPA coating successfully formed stable connections between SCPP fibers and CPC matrix, which simultaneously reinforced biomechanical strength and tenacity (5% SCPP/D/CPC samples exhibited more prominent mechanical property than others). In addition, 5% D/SCPP fibers doped composite cements were characterized as markedly-improved cytocompatibility: Sr²⁺ introduction induced cytoactive and significantly accelerated proliferation, attachment and spreading of osteoblasts. Besides, it also stimulated the secretion of OT, Col-I and ALP from seeded MG63, which was a critical character for further inducing osteogenic process, mineralization and bone tissues formation. The promoted cytocompatibility and improved osteogenesis-related growth factors' secretion could be attributed to constant and controllable release of Sr²⁺ and this deduction was approved by ICP analysis. In addition, Sr doping made this novel cement had a potential efficacy to inhibit aseptic loosening. In a word, present studies all demonstrated 5% SCPP/D/CPC composites could be a potential candidate material employed in bone regeneration and reconstruction for excellent mechanical property and cytocompatibility.

A redox interaction-engaged strategy for multicomponent nanomaterials

The review article focuses on the redox interaction-engaged strategy that offers a powerful way to construct multicomponent nanomaterials with precisely-controlled size, shape, composition and hybridization of nanostructures.

Preparation and Characterization of Polydopamine-Modified Ni/Carbon Nanotubes Friction Composite Coating

In this paper, dopamine (DA) was used for the surface modification of carbon nanotubes (CNTs) to solve the agglomeration problem. High resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) were utilized to understand the morphology and presence of different elements in the modified CNTs. The treated CNT surfaces were wrapped by a pDA layer and the layer thickness was controlled by reaction time. The dispersion test showed that the treated CNTs remained uniformly dispersed in solution for more than 30 days. The Ni/CNTs@pDA composite coating on the mild steel specimen was obtained by the electrodeposition technique. Ball-on-disc friction-wear equipment and an electrochemical workstation were used to test the friction-wear and corrosion resistance of the composite coating. The results indicated that the Ni/CNTs@pDA coating showed excellent tribological performance and were superior to the pure Ni coating.

Time-Dependent Antimicrobial Activity of Filtering Nonwovens with Gemini Surfactant-Based Biocides

Previous studies on nonwovens used for respiratory protective devices (RPDs) were related to equipment intended for short-term use. There is only limited research on the development of biocidal nonwoven fabrics for reusable RPDs that could be used safely in an industrial work environment where there is a risk of microbial growth. Moreover, a new group of biocides with high antimicrobial activity-gemini surfactants, has never been explored for textile's application in previous studies. The aim of this study was to develop high-efficiency melt-blown nonwovens containing gemini surfactants with time-dependent biocidal activity, and to validate their antimicrobial properties under conditions simulating their use at a plant biomass-processing unit. A set of porous biocidal structures (SPBS) was prepared and applied to the melt-blown polypropylene (PP) nonwovens. The biocidal properties of the structures were triggered by humidity and had different activation rates. Scanning electron microscopy was used to undertake structural studies of the modified PP/SPBS nonwovens. In addition, simulation of plant biomass dust deposition on the nonwovens was performed. The biocidal activity of PP/SPBS nonwovens was evaluated following incubation with Escherichia coli and Aspergillus niger from the American Type Culture Collection, and with Pseudomonas fluorescens and Penicillium chrysogenum isolated from the biomass. PP/SPBS nonwovens exhibited antimicrobial activity to varying levels. Higher antimicrobial activity was noted for bacteria (R = 87.85-97.46%) and lower for moulds (R = 80.11-94.53%).

Self-Polymerization of Dopamine in Acidic Environments without Oxygen

An alkaline environment and the presence of oxygen are essential requirements for dopamine polymerization. In this study, we are the first to demonstrate the self-polymerization of dopamine through plasma-activated water (PAW) under acidic environments (pH < 5.5). Resulting poly(dopamine) (PDA) was characterized using Nanosizer, SEM, FTIR, UV-vis, ¹H NMR, and fluorescence spectrophotometers and proved to have similar physical and chemical properties to those polymerized under a basic condition, except that the PDA particles formed in PAW were more stable and hardly aggregated at varied pHs. The PAW polymerization method avoids alkaline solutions and the presence of oxygen and thus extends the applications of dopamine polymerization, particularly in biomedical and pharmaceutical sciences.

Antibacterial and cytocompatible AgNPs constructed with the assistance of Mefp-1 for orthopaedic implants

For the first time, Mefp-1 coating has been used in surface antibacterial and biocompatible modifications based on its multifunctionality.

Anti-cancer activity of camptothecin nanocrystals decorated by silver nanoparticles

CPT/Ag nanocrystals display extreme and broad-spectrum anti-cancer activity and high selectivity through a cooperation effect between CPT and AgNPs.

Epoxy resin reinforced with nanothin polydopamine-coated carbon nanotubes: a study of the interfacial polymer layer thickness

Carbon nanotubes (CNTs) functionalized by a nanothin poly(dopamine) (PDA) layer were produced by a one-pot, nondestructive approach, with direct polymerization of dopamine on the CNT surface.

Polydopamine-induced nanocomposite Ag/CaP coatings on the surface of titania nanotubes for antibacterial and osteointegration functions

A mussel-inspired novel nano silver/calcium phosphate (CaP) composite coating was prepared on anodized Ti, with its surface maintaining preferable biological performance and possessing long-term antibacterial ability.

Surface-independent antibacterial coating using silver nanoparticle-generating engineered mussel glue

During implant surgeries, antibacterial agents are needed to prevent bacterial infections, which can cause the formation of biofilms between implanted materials and tissue. Mussel adhesive proteins (MAPs) derived from marine mussels are bioadhesives that show strong adhesion and coating ability on various surfaces even in wet environment. Here, we proposed a novel surface-independent antibacterial coating strategy based on the fusion of MAP to a silver-binding peptide, which can synthesize silver nanoparticles having broad antibacterial activity. This sticky recombinant fusion protein enabled the efficient coating on target surface and the easy generation of silver nanoparticles on the coated-surface under mild condition. The biosynthesized silver nanoparticles showed excellent antibacterial efficacy against both Gram-positive and Gram-negative bacteria and also revealed good cytocompatibility with mammalian cells. In this coating strategy, MAP-silver binding peptide fusion proteins provide hybrid environment incorporating inorganic silver nanoparticle and simultaneously mediate the interaction of silver nanoparticle with surroundings. Moreover, the silver nanoparticles were fully synthesized on various surfaces including metal, plastic, and glass by a simple, surface-independent coating manner, and they were also successfully synthesized on a nanofiber surface fabricated by electrospinning of the fusion protein. Thus, this facile surface-independent silver nanoparticle-generating antibacterial coating has great potential to be used for the prevention of bacterial infection in diverse biomedical fields.

Immobilization of Lipase on Silver Nanoparticles via Adhesive Polydopamine for Biodiesel Production

Biodiesel production technology is competitive in terms of low cost and alternative source of energy which should be not only sustainable but also environmentally friendly. Designing of the lipase immobilization for biodiesel production has a remarkable impact and is still challenging. In this work, biodiesel production from soybean oil was enhanced and facilitated by using a novel biocatalyst consisting of commercial lipase (EC 3.1.1.3), silver nanoparticles, and polydopamine. Silver nanoparticles (AgNPs) were synthesized with a size range of 10–20 nm. Polydopamine (PD) was delivered by the self-polymerization of dopamine in 10 mM Tris-HCl pH 8.5 and simultaneously coated the AgNPs to form a PD/AgNPs complex. Lipase was immobilized on the PD/AgNPs complex surface via covalent bonds to form a tailor-made biocatalyst consisting of immobilized lipase/PD/AgNPs complex (LPA). The formation and morphology of each composition were characterized by UV-Vis spectroscopy and scanning electron microscope (SEM). Significantly, gas chromatography analysis showed a remarkable biodiesel production yield of 95% by using the LPA complex at 40^°C for 6-hours reaction time, whereas the yield was 86% when using free lyophilized lipase. The LPA complex was apparently reusable after 7 batches and the latter conversion rate of soybean oil was decreased by only 27%.