There has been considerable progress in recent years addressing the clinical and pharmacological limitations of hydrogels for drug delivery applications but substantial challenges remain. Here we discuss overcoming these challenges, particularly with regards to effectively delivering inside body without implantation, prolonging release kinetics drugs from hydrogels, expanding nature which can be delivered using hydrogel-based approaches.

Naturally derived cellulose nanocrystals (CNCs) and nanofibrils (CNFs) are emerging nanomaterials that display high strength, surface area, tunable chemistry, allowing for controlled interactions with polymers, nanoparticles, small molecules, biological materials. Industrial production of nanocelluloses is increasing rapidly several companies already producing on the tons-per-day scale, intensifying quest viable products across many sectors. While hydrophilicity nanocellulose interface has...

Degradable microparticles have broad utility as vehicles for drug delivery and form the basis of several therapies approved by US Food Drug Administration. Conventional emulsion-based methods manufacturing produce particles with a wide range diameters (and thus kinetics release) in each batch. This paper describes fabrication monodisperse, drug-loaded from biodegradable polymers using microfluidic flow-focusing (FF) devices drug-delivery properties those particles. Particles are engineered...

Nanogels and microgels are soft, deformable, penetrable objects with an internal gel-like structure that is swollen by the dispersing solvent. Their softness potential to respond external stimuli like temperature, pressure, pH, ionic strength, different analytes make them interesting as soft model systems in fundamental research well for a broad range of applications, particular field biological applications. Recent tremendous developments their synthesis open access complex architectures...

Temperature-responsive microgels based on poly(N-isopropylacrylamide) (PNIPAM) and functionalized with vinylacetic acid (VAA) are observed to exhibit a host of novel swelling responses compared equally prepared using the conventional acrylic (AA) methacrylic (MAA) comonomers. VAA−NIPAM ionized over narrow pH range show functional group pKa values which independent degree ionization. Ionization induces much larger response in than microgels; upon ionization at physiological temperature,...

Nanocomposite membranes based on thermosensitive, poly(N-isopropylacrylamide)-based nanogels and magnetite nanoparticles have been designed to achieve "on-demand" drug delivery upon the application of an oscillating magnetic field. On−off release sodium fluorescein over multiple cycles has successfully demonstrated using prototype membrane-based devices. The total dose delivered was directly proportional duration "on" pulse. were noncytotoxic, biocompatible, retained their switchable flux...

Injectable hydrogels based on carboxymethyl cellulose and dextran, reinforced with rigid rod-like nanocrystals (CNCs) aldehyde-functionalized CNCs (CHO–CNCs), were prepared characterized. The mechanical properties, internal morphology, swelling of injectable unmodified modified at various loadings examined. In all cases, gelation occurred within seconds as the hydrogel components extruded from a double-barrel syringe, evenly distributed throughout composite, observed by scanning transmission...

Drug delivery devices based on nanocomposite membranes containing thermoresponsive nanogels and superparamagnetic nanoparticles have been demonstrated to provide reversible, on−off drug release upon application (and removal) of an oscillating magnetic field. We show that the dose delivered across membrane can be tuned by engineering phase transition temperature nanogel, loading density in membrane, thickness, allowing for on-state model drugs over at least 2 orders magnitude (0.1−10 μg/h)....

Fabrication of anisotropic hydrogels exhibiting direction-dependent structure and properties has attracted great interest in biomimicking, tissue engineering, bioseparation. Herein, we report a freeze-casting-based fabrication structurally mechanically aerogels composed hydrazone cross-linked poly(oligoethylene glycol methacrylate) (POEGMA) cellulose nanocrystals (CNCs). We show that, by controlling the composition CNC/POEGMA dispersion freeze-casting temperature, with fibrillar, columnar,...

While injectable hydrogels have several advantages in the context of biomedical use, their generally weak mechanical properties often limit applications. Herein, we describe situ-gelling nanocomposite based on poly(oligoethylene glycol methacrylate) (POEGMA) and rigid rod-like cellulose nanocrystals (CNCs) that can overcome this challenge. By physically incorporating CNCs into hydrazone cross-linked POEGMA hydrogels, macroscopic including gelation rate, swelling kinetics, properties,...

Poly(N-isopropylacrylamide) (PNIPAM) microgels are functionalized with aminophenyboronic acid (APBA) to produce nanoparticles which swell in response increases the glucose concentration. A "graft-to" approach was used synthesize a range of different physical properties from same base microgel. Higher APBA graft yields achieved as −COOH groups platform microgel become more localized on surface and highly spaced within subchains. The swelling is enhanced PBA functional outer shell randomly...

Control of the functional group distribution is fundamental importance in design polymer particles, particularly biological applications. Surface-functionalized particles are useful for bioconjugation and medical diagnostics, while internally functionalized may have applications drug delivery. We prepared a series temperature-sensitive poly(N-isopropylacrylamide) (PNIPAM)-based microgels containing carboxylic acid groups via copolymerization with methacrylic acrylamide, which was selectively...

To formulate and characterize a drug-eluting contact lens designed to provide extended, controlled release of drug.Prototype lenses were created by coating PLGA (poly[lactic-co-glycolic acid]) films containing test compounds with pHEMA (poly[hydroxyethyl methacrylate]) ultraviolet light polymerization. The films, encapsulated fluorescein or ciprofloxacin, characterized scanning electron microscopy. Release studies conducted in phosphate-buffered saline at 37 degrees C continuous shaking....

The design and application of soft nanocomposite injectable hydrogels containing entrapped microgels for small-molecule drug delivery is demonstrated. Copolymer based on N-isopropylacrylamide acrylic acid were synthesized that exhibited both ionic hydrophobic affinity binding to bupivacaine, a cationic local anesthetic used as model drug. Microgels subsequently immobilized within an in situ-gelling hydrogel network cross-linked via hydrazide-aldehyde chemistry generate hydrogel-microgel...

Amphoteric, poly(N-isopropylacrylamide)-based microgels are functionalized with aminophenylboronic acid (PBA) functional groups to produce colloidally stable, glucose-responsive gel nanoparticles that exhibit glucose-dependent swelling responses at physiological temperature, pH, and ionic strength. Up 2-fold volumetric observed in response glucose concentrations, the first such reported for a stable microgel. Amphoteric can also be designed both swell deswell according pH of medium,...

ABSTRACT Microgels based on thermally responsive polymers have been widely investigated in the context of controlled release applications, with increasing recent interest developing a clearer understanding what physical, chemical, and biological parameters must be considered to rationally design microgel deliver specific drug at rate physiological context. In this contribution, we outline these key associated engineering microgels for delivery discuss several examples how principles applied...

A series of synthetic oligomers (based on the thermosensitive polymer poly(N-isopropylacrylamide) and carbohydrate polymers (including hyaluronic acid, carboxymethyl cellulose, dextran, methylcellulose) were functionalized with hydrazide or aldehyde functional groups mixed using a double-barreled syringe to create in situ gelling, hydrazone-cross-linked hydrogels. By mixing different numbers ratios reactive oligomer precursors, covalently cross-linked hydrogel networks comprised polymeric...

The design criteria for injectable, <italic>in situ</italic>-gelling hydrogels are reviewed in conjunction with highlights on recent progress the preparation of injectable PEG and PEG-analogue poly(oligoethylene glycol methacrylate) (POEGMA) hydrogels.

The interactions of a range water-soluble drugs different charges and hydrophobicities with carboxylic acid-functionalized poly(N-isopropylacrylamide)-based microgels containing functional group distributions are investigated to determine the impact drug properties microgel morphologies on uptake release. radial distribution acid groups in cationic both strongly affect partitioning between solution phases. Microgels surface-localized bind less than bulk-functionalized microgels, likely due...

Degradable, covalently in situ gelling analogues of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) hydrogels have been designed by mixing aldehyde and hydrazide-functionalized PNIPAM oligomers with molecular weights below the renal cutoff. Co-extrusion reactive polymer solutions through a double-barreled syringe facilitates rapid gel formation within seconds. The resulting hydrazone cross-links hydrolytically degrade over several weeks into low weight oligomers. characteristic...

Cellulose nanocrystals (CNCs) are emerging nanomaterials that form chiral nematic liquid crystals above a critical concentration (C*) and additionally orient within electromagnetic fields. The control over CNC alignment is significant for materials processing end use; to date, magnetic has been demonstrated using only strong fields extended or arbitrary time scales. This work investigates the effects of comparatively weak (0-1.2 T) (1.65-8.25 wt %) on kinetics degree ordering small-angle...

Injectable PEG-analogue hydrogels based on poly(oligoethylene glycol methacrylate) have been developed complementary hydrazide and aldehyde reactive linear polymer precursors. These display the desired biological properties of PEG, form covalent networks in situ following injection, are easily modulated for improved control over their functionality physiochemical properties.