Nanogels For Drug Delivery Research Articles

Recent advances in nanogels for drug delivery and biomedical applications.

Nanotechnology has shown great promise for researchers to develop efficient nanocarriers for better therapy, imaging, and sustained release of drugs. The existing treatments are accompanied by serious toxicity limitations, leading to severe side effects, multiple drug resistance, and off-target activity. In this regard, nanogels have garnered significant attention for their multi-functional role combining advanced therapeutics with imaging in a single platform. Nanogels can be functionalized to target specific tissues which can improve the efficiency of drug delivery and other challenges associated with the existing nanocarriers. Translation of nanogel technology requires more exploration towards stability and enhanced efficiency. In this review, we present the advances and challenges related to nanogels for cancer therapy, ophthalmology, neurological disorders, tuberculosis, wound healing, and anti-viral applications. A perspective on recent research trends of nanogels for translation to clinics is also discussed.

Characterization of Thermoresponsive Poly-N-Vinylcaprolactam Polymers for Biological Applications.

Poly-N-Vinylcaprolactam (PNVCL) is a thermoresponsive polymer that exhibits lower critical solution temperature (LCST) between 25 and 50 °C. Due to its alleged biocompatibility, this polymer is becoming popular for biomedical and environmental applications. PNVCL with carboxyl terminations has been widely used for the preparation of thermoresponsive copolymers, micro- and nanogels for drug delivery and oncological therapies. However, the fabrication of such specific targeting devices needs standardized and reproducible preparation methods. This requires a deep understanding of how the miscibility behavior of the polymer is affected by its structural properties and the solution environment. In this work, PNVCL-COOH polymers were prepared via free radical polymerization (FRP) in order to exhibit LCST between 33 and 42 °C. The structural properties were investigated with NMR, FT-IR and conductimetric titration and the LCST was calculated via UV-VIS and DLS. The LCST is influenced by the molecular mass, as shown by both DLS and viscosimetric values. Finally, the behavior of the polymer was described as function of its concentration and in presence of different biologically relevant environments, such as aqueous buffers, NaCl solutions and human plasma.

Acid degradable poly(vinylcaprolactam)-based nanogels with ketal linkages for drug delivery.

To improve the biocompatibility and biodegradability of nanocarriers, well-defined poly(vinylcaprolactam)-based acid degradable nanogels were fabricated for drug delivery via precipitation polymerization in water, where synthetic ketal-based 2,2-dimethacroyloxy-1-ethoxypropane (DMAEP) acted as a cross-linker, and N-(2-hydroxypropyl)methacrylamide (HPMA) served as a co-monomer. Expectedly, we observed that the temperature and pH of the environment play important roles in the performance of the nanogels. The nanogels were reduced in size upon increasing the temperature and showed higher volume phase transition temperature (VPTT) with higher concentration of HPMA. With the incorporation of ketal linkages, the nanogels showed accelerated degradation profiles by lowering the pH and increasing temperature of the incubation medium. When used as nanocarriers of anticancer drug doxorubicin (DOX), compared to non-degradable nanogels with similar components, the acid-degradable nanogels displayed more effective drug controlled release behaviour, low drug leakage of DOX at neutral pH while rapid and sufficient release from the nanogels under acidic conditions. The results of the cytotoxicity and hemolysis assays further highlighted that the acid-degradable nanogel produced no hemolysin but showed excellent viability to normal cells, and the DOX-loaded nanogel exhibited higher proliferation inhibition against tumor cells.

Synthesis, Molecular Targets, and Antitumor Activities of Substituted Tetrahydro-1- Oxopyrano[4,3-b][1]Benzopyrans and Nanogels for Drug Delivery

A class of substituted 1H,7H-5a,6,8,9-tetrahydro-1-oxopyrano[4,3-b][1]benzopyrans (tricyclic pyrones; TPs) was synthesized from a one-pot condensation reaction of 6-substituted 4-hydroxy-2-pyrones and cyclohexenecarboxaldehydes. The reaction involves a 6pi-electrocyclic ring closing process, and stereo- and regioselectivities were examined. C3-Pyridyl-containing TPs may represent a novel synthetic class of microtubule de-stabilizing anti-cancer drugs that inhibit macromolecule synthesis, tubulin polymerization, and the proliferation of a spectrum of wild-type and multi-drug resistant tumor cell lines in vitro. A linear skeleton with a N-containing aromatic ring attached at C3 of the top A-ring, a central pyran B-ring and a six-membered bottom C-ring with no alkylation at C7 are required for the antitumor activities of the lead compounds, a 3-pyridyl benzopyran (code name H10) and its 2-pyridyl regioisomer (code name H19). In addition to interacting with the colchicine-binding site to inhibit tubulin polymerization and increase the mitotic index, these TP analogs also block the cellular transport of nucleosides to inhibit DNA synthesis more effectively than other antimitotic agents. The anticancer potential of TPs in vivo is suggested by the fact that i.p. injections of H10 decrease the growth of solid tumors in mice inoculated with lung or ovarian carcinomas. A drug-delivery system involving nanogels was studied. We incorporated the anticancer compound, 6-hydroxymethyl-1,4-anthracenedione (code name AQ10) into PEG-PEI nanogel, and found that AQ10-encapsulated nanogel PEG-PEI is significantly more effective in altering the growth of Pan 02 (pancreatic cancer) cells compared to AQ10 or nanogel PEG-PEI alone. Since AQ10 is insoluble in water, PEG-PEI encapsulation represents a way to solubilize and deliver this as well as other poorly soluble compounds.