In Situ Synthesis of Antimicrobial Silver Nanoparticles within Antifouling Zwitterionic Hydrogels by Catecholic Redox Chemistry for Wound Healing Application

Co-deposition towards mussel-inspired antifouling and antibacterial membranes by using zwitterionic polymers and silver nanoparticles

Bacterial attachment and the subsequent colonization on the surfaces of bio-materials usually result in biofilm formation, and thus lead to implant failure, inflammation and so on.

Microwave Synthesis of Chitosan Capped Silver-Dysprosium Bimetallic Nanoparticles: A Potential Nanotheranosis Device

Accurate imaging of the structural and functional state of biological targets is a critical task. To amend paucities associated with individual imaging, there is high interest to develop a multifunctional theranostic devices for cancer diagnosis and therapy. Herein, chitosan coated silver/dysprosium bimetallic nanoparticles (BNPs) were synthesized through a green chemistry route and characterization results inferred that the BNPs are crystalline, spherical, and of size ∼10 nm. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray photoelectron spectroscopy (XPS) confirm the reduced metallic states of Ag and Dy in nanoparticles. These BNPs demonstrate high emission in a second near-infrared (NIR-II, 1000-1400 nm) biological window on excitation at 808 nm. Moreover, magnetization and magnetic resonance imaging (MRI) studies perceive the inherent paramagnetic features of Dy component that displays dark T₂ contrast and high relaxivity. Due to high X-ray attenuation effect, BNPs exhibit better Hounsfield unit (HU) value than the reported contrast agents. BNPs unveil good biocompatibility and also express sturdy therapeutic effect in HeLa cells when tethered with doxorubicin.

Governing factors affecting the impacts of silver nanoparticles on wastewater treatment

Silver nanoparticles (nanosilver or AgNPs) enter municipal wastewater from various sources, raising concerns about their potential adverse effects on wastewater treatment processes. We argue that the biological effects of silver nanoparticles at environmentally realistic concentrations (μgL^-1 or lower) on the performance of a full-scale municipal water resource recovery facility (WRRF) are minimal. Reactor configuration is a critical factor that reduces or even mutes the toxicity of silver nanoparticles towards wastewater microbes in a full-scale WRRF. Municipal sewage collection networks transform silver nanoparticles into silver(I)-complexes/precipitates with low ecotoxicity, and preliminary/primary treatment processes in front of biological treatment utilities partially remove silver nanoparticles to sludge. Microbial functional redundancy and microbial adaptability to silver nanoparticles also greatly alleviate the adverse effects of silver nanoparticles on the performance of a full-scale WRRF. Silver nanoparticles in a lab-scale bioreactor without a sewage collection system and/or a preliminary/primary treatment process, in contrast to being in a full scale system, may deteriorate the reactor performance at relatively high concentrations (e.g., mgL^-1 levels or higher). However, in many cases, silver nanoparticles have minimal impacts on lab-scale bioreactors, such as sequencing batch bioreactors (SBRs), especially when at relatively low concentrations (e.g., less than 1mgL^-1). The susceptibility of wastewater microbes to silver nanoparticles is species-specific. In general, silver nanoparticles have higher toxicity towards nitrifying bacteria than heterotrophic bacteria.

Bioengineered silver nanoparticles using Curvularia pallescens and its fungicidal activity against Cladosporium fulvum

Microorganisms based biosynthesis of nanomaterials has triggered significant attention, due to their great potential as vast source of the production of biocompatible nanoparticles (NPs). Such biosynthesized functional nanomaterials can be used for various biomedical applications. The present study investigates the green synthesis of silver nanoparticles (Ag NPs) using the fungus Curvularia pallescens (C. pallescens) which is isolated from cereals. The C. pallescens cell filtrate was used for the reduction of AgNO₃ to Ag NPs. To the best of our knowledge C. pallescens is utilized first time for the preparation of Ag NPs. Several alkaloids and proteins present in the phytopathogenic fungus C. pallescens were mainly responsible for the formation of highly crystalline Ag NPs. The as-synthesized Ag NPs were characterized by using UV–Visible spectroscopy, X-ray diffraction and transmission electron microscopy (TEM). The TEM micrographs have revealed that spherical shaped Ag NPs with polydisperse in size were obtained. These results have clearly suggested that the biomolecules secreted by C. pallescens are mainly responsible for the formation and stabilization of nanoparticles. Furthermore, the antifungal activity of the as-prepared Ag NPs was tested against Cladosporium fulvum, which is the major cause of a serious plant disease, known as tomato leaf mold. The synthesized Ag NPs displayed excellent fungicidal activity against the tested fungal pathogen. The extreme zone of reduction occurred at 50 μL, whereas, an increase in the reduction activity is observed with increasing the concentration of Ag NPs. These encouraging results can be further exploited by employing the as synthesized Ag NPs against various pathogenic fungi in order to ascertain their spectrum of fungicidal activity.

In Situ Impregnation of Silver Nanoclusters in Microporous Chitosan-PEG Membranes as an Antibacterial and Drug Delivery Percutaneous Device

An in situ synthesis method for preparing silver nanoclusters (AgNCs) embedded in chitosan-polyethylene glycol (CS-PEG) membranes is disclosed. The aim is to develop implantable multifunctional devices for biofilm inhibition and drug release to reduce percutaneous device related complications (PDRCs). A multiple array of characterization techniques confirmed the formation of fluorescent AgNCs with sizes of ∼3 nm uniformly distributed in CS-PEG matrix and their active role in determining the fraction and interconnectivity of the microporous membranes. The presence and increasing contents of AgNCs enhanced the mechanical stability of membranes and decreased their susceptibility to degradation in the presence of lysozyme and H₂O₂. Moreover, the presence and increasing concentrations of AgNCs hindered biofilm formation against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) and enabled a sustainable release of an anti-inflammatory drug naproxen in vitro until 24 h. The overall results gathered and reported in this work make the AgNCs impregnated CS-PEG membranes highly promising multifunctional devices combining efficient antibacterial activity and biocompatibility with active local drug delivery.

Angiogenic Effects of Collagen/Mesoporous Nanoparticle Composite Scaffold Delivering VEGF165

Vascularization is a key issue for the success of tissue engineering to repair damaged tissue. In this study, we report a composite scaffold delivering angiogenic factor for this purpose. Vascular endothelial growth factor (VEGF) was loaded on mesoporous silica nanoparticle (MSN), which was then incorporated within a type I collagen sponge, to produce collagen/MSN/VEGF (CMV) scaffold. The CMV composite scaffold could release VEGF sustainably over the test period of 28 days. The release of VEGF improved the cell proliferation. Moreover, the in vivo angiogenesis of the scaffold, as studied by the chick chorioallantoic membrane (CAM) model, showed that the VEGF-releasing scaffold induced significantly increased number of blood vessel complexes when compared with VEGF-free scaffold. The composite scaffold showed good biocompatibility, as examined in rat subcutaneous tissue. These results demonstrate that the CMV scaffold with VEGF-releasing capacity can be potentially used to stimulate angiogenesis and tissue repair.

Zwitterionic hydrogels promote skin wound healing

Skin traumas are among the most common health problems in the world, and are routinely treated with wound dressings such as bandages and gauze. Traditional dressings are typically made of dry cotton, which tends to adhere to the wound, causing scab formation and bacterial infections. Ideally, a dressing should accelerate wound healing while avoiding any side effects or complications. Recent studies have found that wet dressings, especially hydrogels, can provide a moist environment for wounds that mimics the in vivo environment, thus facilitating debridement of necrotic tissue, enhancing tissue regeneration, and avoiding scab formation. Zwitterionic hydrogels exhibit strong hydration, are biomimetic in nature, and show excellent anti-fouling properties; their resulting high water content, excellent biocompatibility, and negligible interactions with proteins and cells make them ideal wet wound dressings. In this work, we demonstrated that zwitterionic hydrogels, especially poly-carboxybetaine (PCB) hydrogels, can efficiently promote skin wound healing. Skin wounds treated with zwitterionic hydrogels healed significantly better than those treated with PHEMA hydrogels and the commercial product DuoDerm. Moreover, these zwitterionic hydrogels can be easily coated on cotton gauze or bandage pads for easy handling and application. The findings in this work hold great promise for the development of next-generation wound dressings to improve healthcare.

Mussel inspired locomotive: the moisture induced actuation in a poly(vinyl alcohol) film containing melanin-like dopamine nano spheres

We report here for the first time a PVA film incorporated with PDNs that is capable of fast and perpetual motion driven by a humidity gradient.