First successful design of semi-IPN hydrogel–silver nanocomposites: A facile approach for antibacterial application

Development of Nano-Antimicrobial Biomaterials for Biomedical Applications

Around the globe, there is a great concern about controlling growth of pathogenic microorganisms for the prevention of infectious diseases. Moreover, the greater incidences of cross contamination and overuse of drugs has contributed towards the development of drug resistant microbial strains making conditions even worse. Hospital acquired infections pose one of the leading complications associated with implantation of any biomaterial after surgery and critical care. In this regard, developing non-conventional antimicrobial agents which would prevent the aforementioned causes is under the quest. The rapid development in nanoscience and nanotechnology has shown promising potential for developing novel biocidal agents that would integrate with a biomaterial to prevent bacterial colonization and biofilm formation. Metals with inherent antimicrobial properties such as silver, copper, zinc at nano scale constitute a special class of antimicrobials which have broad spectrum antimicrobial nature and pose minimum toxicity to humans. Hence, novel biomaterials that inhibit microbial growth would be of great significance to eliminate medical device/instruments associated infections. This chapter comprises the state-of-art advancements in the development of nano-antimicrobial biomaterials for biomedical applications. Several strategies have been targeted to satisfy few important concern such as enhanced long term antimicrobial activity and stability, minimize leaching of antimicrobial material and promote reuse. The proposed strategies to develop new hybrid antimicrobial biomaterials would offer a potent antibacterial solution in healthcare sector such as wound healing applications, tissue scaffolds, medical implants, surgical devices and instruments.

Guar gum as a promising starting material for diverse applications: A review

Guar gum is the powdered endosperm of the seeds of the Cyamopsis tetragonolobus which is a leguminous crop. The endosperm contains a complex polysaccharide called galactomannan, which is a polymer of d-galactose and d-mannose. This hydroxyl group rich polymer when added to water forms hydrogen bonding imparting significant viscosity and thickening to the solution. Due to its thickening, emulsifying, binding and gelling properties, quick solubility in cold water, wide pH stability, film forming ability and biodegradability, it finds applications in large number of industries. In last few decades a lot of research has been done on guar gum to fit it into particular application, as such or by its structural modifications. This review gives an overview of the nature, chemistry and properties of guar gum and discusses recent developments in its modifications and applications in major industries like hydraulic fracturing, explosives, food, agriculture, textile, paper, cosmetics, bioremediation, drug delivery, medical and pharmaceuticals. This article would help researchers engaged in biopolymer area and other end-users who want to begin research in natural polysaccharides.

Ultraviolet-induced polymerization of superabsorbent composites based on sodium humate and its urea release behavior

This study was carried out to develop a superabsorbent composite for agriculture application, which is based on acrylic acid and sodium humate and prepared by ultraviolet-induced polymerization in the presence of crosslinker and composite initiator.

BMSCs-laden gelatin/sodium alginate/carboxymethyl chitosan hydrogel for 3D bioprinting

Gelatin/sodium alginate/carboxymethyl chitosan hydrogel mixed with bone mesenchymal stem cells for 3D bioprinting.

Composites of Polymer Hydrogels and Nanoparticulate Systems for Biomedical and Pharmaceutical Applications

Due to their unique structures and properties, three-dimensional hydrogels and nanostructured particles have been widely studied and shown a very high potential for medical, therapeutic and diagnostic applications. However, hydrogels and nanoparticulate systems have respective disadvantages that limit their widespread applications. Recently, the incorporation of nanostructured fillers into hydrogels has been developed as an innovative means for the creation of novel materials with diverse functionality in order to meet new challenges. In this review, the fundamentals of hydrogels and nanoparticles (NPs) were briefly discussed, and then we comprehensively summarized recent advances in the design, synthesis, functionalization and application of nanocomposite hydrogels with enhanced mechanical, biological and physicochemical properties. Moreover, the current challenges and future opportunities for the use of these promising materials in the biomedical sector, especially the nanocomposite hydrogels produced from hydrogels and polymeric NPs, are discussed.

In situ assembly of antifouling/bacterial silver nanoparticle-hydrogel composites with controlled particle release and matrix softening

Controlling bacterial contamination has been a major challenge for protecting human health and welfare. In this context, hydrogels loaded with silver nanoparticles have been used to prevent biofilm formation on substrates of interest. However, such gel composites are often plagued by rapid loss of silver nanoparticles and matrix softening, and thus the gel becomes less effective for antifouling. To this end, this study demonstrates that in situ photoreaction of an aqueous mixture of silver nitrates, poly(ethylene glycol) diacrylate, and vinylpyrrolidone results in a silver nanoparticle-laden hydrogel composite with minimal nanoparticle loss and matrix softening due to enhanced binding between nanoparticles and the gel. The resulting gel composite successfully inhibits the bacterial growth in media and the bacterial adhesion to surfaces of interest. We suggest that the results of this study serve to advance quality of materials with antifouling/bacterial activities.

Clinical and Antibiofilm Efficacy of Antimicrobial Hydrogels

Significance: Hydrogels have been shown to have a significant role to play in wound healing. Hydrogels are used to assist in the management of dry, sloughy, or necrotic wounds. However, recent scientific evidence has shown that biofilms delay wound healing and increase a wound propensity to infection. It is therefore essential that hydrogels incorporating antimicrobials demonstrate efficacy on biofilms. Consequently, it is the aim of this article to review the efficacy of hydrogels, incorporating antimicrobials, on wounds with specific reference to their efficacy on biofilms. Recent Advances: Technologies being developed for the management of wounds are rapidly expanding. In particularly next-generation hydrogels, incorporating copolymers, have been reported to enable the smart release of antimicrobials. This has led to the development of a more tailored patient-specific antimicrobial hydrogel therapy. Critical Issues: Evidence relating to the efficacy of hydrogels, incorporating antimicrobials, on biofilms within both the in vitro and in vivo environments is lacking. Future Direction: Studies that investigate the efficacy of antimicrobial hydrogel wound dressings on both in vivo and in vitro biofilms are important. However, there is a significant need for better and more reproducible in vivo biofilm models. Until this is possible, data generated from appropriate and representative in vitro models will help to assist researchers and clinicians in evaluating antimicrobial and antibiofilm hydrogel technology for the extrapolation of efficacy data relevant to biofilms present in the in vivo environment.

Nanoparticle-Hydrogel Composites: Concept, Design, and Applications of These Promising, Multi-Functional Materials

New technologies rely on the development of new materials, and these may simply be the innovative combination of known components. The structural combination of a polymer hydrogel network with a nanoparticle (metals, non-metals, metal oxides, and polymeric moieties) holds the promise of providing superior functionality to the composite material with applications in diverse fields, including catalysis, electronics, bio-sensing, drug delivery, nano-medicine, and environmental remediation. This mixing may result in a synergistic property enhancement of each component: for example, the mechanical strength of the hydrogel and concomitantly decrease aggregation of the nanoparticles. These mutual benefits and the associated potential applications have seen a surge of interest in the past decade from multi-disciplinary research groups. Recent advances in nanoparticle-hydrogel composites are herein reviewed with a focus on their synthesis, design, potential applications, and the inherent challenges accompanying these exciting materials.

Antimicrobial polymers with metal nanoparticles

Metals, such as copper and silver, can be extremely toxic to bacteria at exceptionally low concentrations. Because of this biocidal activity, metals have been widely used as antimicrobial agents in a multitude of applications related with agriculture, healthcare, and the industry in general. Unlike other antimicrobial agents, metals are stable under conditions currently found in the industry allowing their use as additives. Today these metal based additives are found as: particles, ions absorbed/exchanged in different carriers, salts, hybrid structures, etc. One recent route to further extend the antimicrobial applications of these metals is by their incorporation as nanoparticles into polymer matrices. These polymer/metal nanocomposites can be prepared by several routes such as in situ synthesis of the nanoparticle within a hydrogel or direct addition of the metal nanofiller into a thermoplastic matrix. The objective of the present review is to show examples of polymer/metal composites designed to have antimicrobial activities, with a special focus on copper and silver metal nanoparticles and their mechanisms.

Development and application of a nanocomposite derived from crosslinked HPMC and Au nanoparticles for colon targeted drug delivery

Herein, we report a novel route for the synthesis of poly(acrylamide) (PAAm) crosslinked hydroxypropyl methyl cellulose/Au nanocomposite where chemically crosslinked HPMC (c-HPMC) works as a reducing agent.

Antibacterial nanocomposite hydrogels for superior biomedical applications: a Facile eco-friendly approach

Antibacterial Au-core Ag-shell Carbopol® 980 NF/Noveon® AA-1 polycarbophil nanocomposite hydrogels were fabricated by nucleation of Au³⁺ and Ag⁺ ions from the extracts of mint leaves by facile eco-friendly approach.

Effect of synthesis routes on the properties and bactericidal activity of cryogels incorporated with silver nanoparticles

AgNPs-incorporated cryogels prepared via three synthesis routes were explored as antibacterial sorbents for water disinfection.

Eco-friendly superabsorbent composite based on sodium alginate and organo-loess with high swelling properties

A novel superabsorbent composite with high swelling properties was synthesized by the grafted co-polymerization of partially neutralized acrylic acid (AA) onto a sodium alginate (NaAlg) backbone in the presence of organo-loess.

Ag-nanogel blended polymeric membranes with antifouling, hemocompatible and bactericidal capabilities

A highly efficient, universal and convenient protocol is reported to fabricate antifouling, hemocompatible, and bactericidal membranes by physically blending of antifouling nanogels and in situ silver nanoparticles immobilization.

Designing casein-coated iron oxide nanostructures (CCIONPs) as superparamagnetic core-shell carriers for magnetic drug targeting

Magnetic drug targeting is a drug delivery system applicable to cancer treatment. Coated magnetic particles, called carriers, are very useful for delivering chemotherapeutic drugs. In the present research, casein-coated iron oxide nanocarriers (CCIONPs) of core shell nanostructure have been described as being applicable to magnetic drug targeting. The structure, morphology, and composition of prepared magnetic nanoparticles were determined by analytical techniques like Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Electron diffraction (ED), X-ray diffraction (XRD), Zeta potential, Dynamic light scattering (DLS), Mossbauer and Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Vibrating sample magnetometery (VSM)) and in vitro cytotoxicity analysis. Magnetization studies of CCIONPs conducted at room temperature using a vibrating sample magnetometer suggested their superparamagnetic nature as having a saturation magnetization (Ms) of 64 emu g⁻¹ at an applied magnetic field of 5 kOe. The size of the magnetic polymeric nanoparticles was found to lie in the range of 73.9 ±0.36 nm, and the particles exhibited superparamagnetic behavior. The prepared particles could be used as a drug carrier for controlled and targeted drug delivery.

Investigation of magnetically controlled water intake behavior of Iron Oxide Impregnated Superparamagnetic Casein Nanoparticles (IOICNPs)

Iron oxide impregnated casein nanoparticles (IOICNPs) were prepared by in-situ precipitation of iron oxide within the casein matrix. The resulting iron oxide impregnated casein nanoparticles (IOICNPs) were characterized by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), Vibrating sample magnetometer (VSM) and Raman spectroscopy. The FTIR analysis confirmed the impregnation of iron oxide into the casein matrix whereas XPS analysis indicated for complete oxidation of iron (II) to iron(III) as evident from the presence of the observed representative peaks of iron oxide. The nanoparticles were allowed to swell in phosphate buffer saline (PBS) and the influence of factors such as chemical composition of nanoparticles, pH and temperature of the swelling bath, and applied magnetic field was investigated on the water intake capacity of the nanoparticles. The prepared nanoparticles showed potential to function as a nanocarrier for possible applications in magnetically targeted delivery of anticancer drugs.

Surface-engineered nanogel assemblies with integrated blood compatibility, cell proliferation and antibacterial property: towards multifunctional biomedical membranes

This study presents the fabrication of multifunctional nanolayers on biomedical membrane surfaces by using LBL self-assembly of nanogels and heparin-like polymers.

Segregated polymeric nanocomposites with tunable three-dimensional network of nanoparticles by controlling the dispersion and distribution

A facile and robust emulsion approach for fabrication of segregated polymeric nanocomposites with controllable nanoparticle dispersion/distribution is described.

A Green Approach to Synthesize Silver Nanoparticles in Starch-co-Poly(acrylamide) Hydrogels by Tridax procumbens Leaf Extract and Their Antibacterial Activity

A series of starch-co-poly(acrylamide) (starch-co-PAAm) hydrogels were synthesized by employing free radical redox polymerization. A novel green approach, Tridax procumbens (TD) leaf extract, was used for reduction of silver ions (Ag+) into silver nanoparticles in the starch-co-PAAm hydrogel network. The formation of silver nanoparticles was confirmed by UV-visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (X-RD) studies. 22% of weight loss difference between hydrogel and silver nanocomposite hydrogel (SNCH) clearly indicates the formation of silver nanoparticles by TGA. TEM images indicate the successful incorporation of silver nanoparticles ranging from 5 to 10 nm in size and spherical in shape with a narrow size distribution. These developed SNCHs were used to study the antibacterial activity by inhibition zone method against gram-positive and gram-negative bacteria such as Bacillus and Escherichia coli. The results indicated that these SNCHs can be used potentially for biomedical applications.

UV-irradiation-induced templated/in-situ formation of ultrafine silver/polymer hybrid nanoparticles as antibacterial

Two types of facile approaches toward ultrafine Ag/polymer hybrid nanoparticles (NPs) within 10 nm are introduced. Template and in-situ formation method are developed by photoreduction based on inverse microemulsion (IME) polymerization of N,N-dimethylacrylamide (DMAA). The template method refers to the usage of size-varied polymeric PDMAA NPs as templates for the preparation of Ag/PDMAA hybrids with desired morphology and optical property. To avoid the self-seeding nucleation of free Ag(+) in the solution, in-situ formation method is developed by introducing AgNO3 during IME polymerization, in which product hybrids could be obtained via autoprecipitation in large scale. Additionally, the produced Ag/PDMAA hybrids show high antibacterial performance.

Antimicrobial hydrogels for the treatment of infection

The increasing prevalence of microbial infections, especially those associated with impaired wound healing and biomedical implant failure has spurred the development of new materials having antimicrobial activity. Hydrogels are a class of highly hydrated material finding use in diverse medical applications such as drug delivery, tissue engineering, as wound fillers, and as implant coatings, to name a few. The biocompatible nature of many gels make them a convenient starting platform to develop selectively active antimicrobial materials. Hydrogels with antimicrobial properties can be obtained through the encapsulation or covalent immobilization of known antimicrobial agents, or the material itself can be designed to possess inherent antimicrobial activity. In this review we present an overview of antimicrobial hydrogels that have recently been developed and when possible provide a discussion relevant to their mechanism of action.

Bactericidal effect of poly(acrylamide/itaconic acid)-silver nanoparticles synthesized by gamma irradiation against Pseudomonas aeruginosa

Antimicrobial activity of silver nanoparticles is gaining importance due its broad spectrum of targets in cell compared to conventional antimicrobial agents. In this context, silver nanoparticles were synthesized by gamma irradiation-induced reduction method of acrylamide and itaconic acid with irradiation dose up to 70 kGy. Silver nanoparticles were examined by Fourier-transform infrared, scanning electron microscopic images (SEM), and ultraviolet-visible spectrophotometer. The particle size was determined by X-ray diffraction, transmission electron microscopy (TEM), and dynamic light scattering. The antibacterial effect was studied by disk diffusion method against some bacterial pathogenic strains. Silver nanoparticles showed promising activity against Pseudomonas aeruginosa and slightly active against Escherichia coli, methicillin-resistant Staphylococcus aureus, and Klebsiella pneumonia. The bactericidal effect of silver nanoparticles was tested against P. aeruginosa. The killing rate of P. aeruginosa was found to be 90 % of viability at (100 μl/ml) of silver nanoparticles. Exposure of P. aeruginosa cells to silver nanoparticles caused fast loss of 260 nm absorbing materials and release of potassium ions. The TEM and SEM observation showed that silver nanoparticles may destroy the structure of bacterial cell membrane in order to enter the bacterial cell resulting in the leakage of the cytoplasmic component and the eventual death.