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Nanogels are being explored as drug delivery agents for targeting cancer due to their easy tailoring properties and ability to efficiently encapsulate therapeutics of diverse nature through simple mechanisms. Nanogels are proficiently internalized by the target cells, avoid accumulating in nontarget tissues thereby lower the therapeutic dosage and minimize harmful side effects. However, there is an urgent need for relevant clinical data from nanogels so as to allow translation of the nanogel concept into a viable therapeutic application for the treatment of cancer. This review highlights some of the recent progress in nanogels as a carrier in the field of nanomedicine for the treatment of cancer. The present review critically analyzes the use of extracellular pH targeting for nanogels, siRNA delivery, PEGylated nanogels, multi-responsive nanogels and intracellular delivery of nanogels for improved therapy of cancer.

pH/redox dual-responsive nanogels (DEX-SS) were prepared by precipitation polymerization of methacrylated dextran (DEXMA), 2-aminoethylmethacrylate (AEMA) and N,N′-bis(acryloyl)cystamine (BAC), and then loaded with methotrexate (MTX). Nanogels were spherical and exhibited homogeneous size distribution (460 nm, PDI < 0.30) as observed using dynamic light scattering (DLS) and scanning electron microscopy (SEM). DEX-SS were sensitive to the variations of pH and redox environment. Nanogels incubated in buffer pH 5.0 containing 10 mM glutathione (GSH) synergistically increased the mean diameter and the PDI to 750 nm and 0.42, respectively. In vitro release experiments were performed at pH 7.4 and 5.0 with and without GSH. The cumulative release of MTX in pH 5.0 medium with 10 mM GSH was 5-fold higher than that recorded at pH 7.4 without GSH. Fibroblasts and tumor cells were used to tests the effects of blank DEX-SS and MTX@DEX-SS nanogels on cell viability. Remarkable influence of pH on nanogels internalization into HeLa cells was evidenced by means of confocal microscopy and flow cytometry. [ABSTRACT FROM AUTHOR]

The “click” characteristics of nucleophilic opening of epoxide have recently been exploited for the development of a functional hydrogel particle system based on commercially available bisepoxide and triamine polyetheramine monomers. Key features of these particles include high cationic charges and responsiveness to temperature, pH, and oxidation. Despite these advantages, the cytocompatibility of these particles must be considered prior to use in biomedical applications. Here we demonstrate that, by introducing a diamine polyetheramine as a comonomer in the “click” reaction, and tuning its molar ratio with the triamine monomer, cationic nanoparticles with improved cytocompatibility can be prepared. The reduced cytotoxicity is primarily due to the hydrophilic backbone of the diamine comonomer, which has polyethylene glycol as a primary component. The resulting nanoparticles formed from the diamine comonomer exhibited a lower surface charge, while maintaining a comparable size. In addition, the responsiveness of the nanoparticles to temperature, pH, and oxidation was conserved, while achieving greater colloidal stability at basic pH. Results from this study further demonstrated that the nanoparticles were able to encapsulate Nile red, a model for hydrophobic drug molecules, were effective against the bacteria Staphylococcus aureus , and were capable of binding DNA through ionic complexation. Based on the results from this work, the use of diamine comonomers significantly reduces the cytotoxicity of similarly developed hydrogel nanoparticles, allowing for numerous biomedical applications, including nanocarriers for therapeutic agents with poor water solubility, treatment of bacterial infection, and non-viral vectors for gene therapy. Statement of Significance In recent years significant attention has been placed on the development of nanocarriers for numerous biomedical applications. Of particular interest are cationic polymers, which contain high positive surface charges that allow binding of numerous therapeutic agents. Unfortunately, the advantages of cationic polymers for binding, are often negated by the tendency of these polymers to be cytotoxic. Previous studies have developed highly responsive cationic hydrogel nanoparticles, which meet several of the criteria for biomedical applications, but were acutely cytotoxic. In this work, cationic hydrogel nanoparticles, with significantly improved cytocompatibility, were synthesized using simple, green epoxy chemistry. In addition, the ability of these nanoparticles to maintain a small size (<500 nm), bind DNA, encapsulate hydrophobic drugs, and kill bacteria was maintained. [ABSTRACT FROM AUTHOR]

Nanogels are being explored as drug delivery agents for targeting cancer due to their easy tailoring properties and ability to efficiently encapsulate therapeutics of diverse nature through simple mechanisms. Nanogels are proficiently internalized by the target cells, avoid accumulating in nontarget tissues thereby lower the therapeutic dosage and minimize harmful side effects. However, there is an urgent need for relevant clinical data from nanogels so as to allow translation of the nanogel concept into a viable therapeutic application for the treatment of cancer. This review highlights some of the recent progress in nanogels as a carrier in the field of nanomedicine for the treatment of cancer. The present review critically analyzes the use of extracellular pH targeting for nanogels, siRNA delivery, PEGylated nanogels, multi-responsive nanogels and intracellular delivery of nanogels for improved therapy of cancer. [ABSTRACT FROM AUTHOR]

Nanogels are hydrophilic polymers made up of crosslinked nano-sized particles. These nanogels have large surface area that offers several functional groups as reserves for binding drugs, generating biosensors and as supports for enzyme immobilization. This mini-review is an attempt to evaluate the recent developments in the use of nanogels as supports in enzyme immobilization. Emphasis is laid on the effect of nanogel structure and immobilization protocol on the property profile of the immobilized enzymes as comparedwith their free counterparts. The prospective applications of the nanogel-immobilized enzymes are also evaluated. [ABSTRACT FROM AUTHOR]