Recent Advances in the Biomedical Applications of Functionalized Nanogels

Abstract

Nanomaterials have been extensively used in several applications in the past few decades related to biomedicine and healthcare. Among them, nanogels (NGs) have emerged as an important nanoplatform with the properties of both hydrogels and nanoparticles for the controlled/sustained delivery of chemo drugs, nucleic acids, or other bioactive molecules for therapeutic or diagnostic purposes. In the recent past, significant research efforts have been invested in synthesizing NGs through various synthetic methodologies such as free radical polymerization, reversible addition-fragmentation chain-transfer method (RAFT) and atom transfer radical polymerization (ATRP), as well as emulsion techniques. With further polymeric functionalizations using activated esters, thiol–ene/yne processes, imines/oximes formation, cycloadditions, nucleophilic addition reactions of isocyanates, ring-opening, and multicomponent reactions were used to obtain functionalized NGs for targeted delivery of drug and other compounds. NGs are particularly intriguing for use in the areas of diagnosis, analytics, and biomedicine due to their nanodimensionality, material characteristics, physiological stability, tunable multi-functionality, and biocompatibility. Numerous NGs with a wide range of functionalities and various external/internal stimuli-responsive modalities have been possible with novel synthetic reliable methodologies. Such continuous development of innovative, intelligent materials with novel characteristics is crucial for nanomedicine for next-generation biomedical applications. This paper reviews the synthesis and various functionalization strategies of NGs with a focus on the recent advances in different biomedical applications of these surface modified/functionalized single-/dual-/multi-responsive NGs, with various active targeting moieties, in the fields of cancer theranostics, immunotherapy, antimicrobial/antiviral, antigen presentation for the vaccine, sensing, wound healing, thrombolysis, tissue engineering, and regenerative medicine.

Biomaterials Based on Organic Polymers and Layered Double Hydroxides Nanocomposites: Drug Delivery and Tissue Engineering

“…As mentioned above, to improve the properties of the polymers (or co-polymers) and add functionalities, their bulky surfaces can be modified to increase, for instance, wettability, biodegradability, bioavailability, cell adhesion, and cell internalization [ 41 , 42 ]. Through organic chemical reactions (amide or ester bonds formation, click chemistry, ring-opening etc.…”

Controlled polymerization in microfluidics: Advancement in nanogel synthesis

“…This process is reversible, allowing for the precise control of polymer chain length. 18,19 Deactivation A dormant species is formed by the reversible transfer of an atom (usually a halogen) from the polymer chain back to the transition metal complex. This deactivation step allows for the control of the polymerization kinetics.…”

Advances in Nanogels for Topical Drug Delivery in Ocular Diseases

“…In recent years, scientists have investigated and created many novel types of ophthalmic formulations, including micelles, liposomes, nanoparticles, nanosuspensions, dendritic polymers, microneedles, cubosomes, niosomes, nanowafers, etc., providing a number of alternatives to the drug delivery of traditional ophthalmic formulations [ 13 ]. Nanogels are formed from natural polymers, synthetic polymers, or a combination thereof, and their three-dimensional network structure allows for the encapsulation of small molecules, oligonucleotides, and even proteins [ 14 ], whose unique characteristics make it possible for drug delivery, diagnostics, and imaging and have great potential for application in the biomedical, tissue engineering, and pharmaceutical fields [ 15 , 16 , 17 , 18 , 19 ]. Recently, the application of nanogels in the eye has attracted more attention, not only as an upgrade to hydrogels or microgels [ 20 ] but also as a nanocarrier that can be combined with micelles, liposomes, dendritic polymers, etc., which are superior alternatives since they have higher biocompatibility, drug loading capacity, and lower toxicity [ 21 , 22 , 23 ].…”