‘CuAAC’-mediated 1,2,3-triazole appended polymeric nanogel systems based on different types of polymer/polymeric systems and functionalization agents with their corresponding characteristic aspects and functions.

Entry	Nanogel material	Basic structure	Aspect(s) of nanogel	Key function(s)	Reference
1	Boltorn® H40 and poly(vinylpyridine) nanogel		CuAAC assisted in covalent bond formation resulting in the chemically cross-linked nanogels comprising hyperbranched dendrimer (H40-PCL) with PVP as a crosslinker through mini emulsion polymerization	pH-sensitive nanogel utilized in the release of a hydrophobic anti-cancer medication	128
2	Nanogel formed through diacetylenic-based glycolipids		The presence of a 1,2,3-triazole ring between the hydrophobic and hydrophilic part of the diacetylene-based glycolipids resulted in their self-organization into 1D-nanotubes, and at higher concentrations, these bundled nanotubes crosslinked to form the nanogels	Nanocontainer for cytotoxic topotecan drug incorporation and its site-specific release	129
3	Poly(ethylene glycol) (PEG) monomers-based nanogel		Alkyne and azide functionalized PEG monomers were crosslinked via CuAAC to synthesize the nanogel and the polymerization was subsequently ceased by the addition of a Cu-chelating agent	The nanogel coatings efficiently exhibit short-term protein resistance, encompassing superior surfaces which could be well utilized for in vitro diagnostics	130
4	Ga-porphyrin-OH nanogel based on PEG		Fluorescent nanogel synthesized via reverse (mini)emulsion-CuAAC having uniform size	Applicability in near-infrared (NIR) imaging due to their fluorescence and cell affinity	131
5	Ga-porphyrin-FA nanogel based on PEG		The diameter of nanogels ranged between 30–120 nm, with an emission maximum between 700 and 800 nm. Applicability in near-infrared (NIR) imaging due to their fluorescence and cell affinity	Folate immobilization on the surface to target tumor cells for cell imaging and drug release	131
6	Hydroxyethyl methacrylate (HEMA), acrylated methyl ether poly (ethylene glycol) (ACMPEG), and Fe3O4 based nanogel		Click chemistry and surfactant-free emulsion photopolymerization in combination to produce amphiphilic nanogels from vinylated SPIONs/HEMA/PEG	Carrier for the anti-cancer drug quercetin	132
7	Polyethylene glycol (PEG), polyethyleneimine (PEI), and rhodamine-based nanogel		The nanostructures were biodegradable and appropriate for transporting drugs or genetic material and also could be tracked as they interacted with the cells	Drug delivery devices for sustained release of the succinimide anticonvulsant drug ethosuximide	133
8	Polyethylene glycol (PEG), polyethyleneimine (PEI), and rhodamine-based nanogel		The nanostructures were biodegradable and appropriate for transporting drugs or genetic material and also could be tracked as they interacted with the cells	Drug delivery devices for sustained release of the succinimide anticonvulsant drug ethosuximide	133
9	Polyethylene glycol (PEG), and polyethyleneimine (PEI) based nanogel framed via rhodamine		The potential of the nanogels to enhance or decrease microglia internalization was evaluated after they were coated with various concentrations of PEG monomethyl ether	Transportation of drugs or genes into the microglia environment, enhancing their therapeutic efficacy for reduction of microglia internalization	134
10	Polyethylene glycol and polyethyleneimine based nanogel		The nanogel loaded with the anti-hepatic stetosis properties bearing polyphenol i.e., hydroxytyrosol (HT) on in vitro administration exhibit the reduction of intracellular triglyceride levels	Potential pharmacological treatment of non-alcoholic fatty liver disease (NAFLD)	135
11	Polyethylene glycol and polyethyleneimine-based nanogels with high colloidal stability and biocompatibility		RhB and Cy5 fluorescent dyes bearing azide groups were used for the synthesis of the nanogels and utilizing the unreacted amines in the PEI chains, the primary amines linkers were grafted around the nanogel surface	Drug carrier for rolipram to reduce astrogliosis	136
12	Amine and pyridine-functionalized PEG-PEI based nanogel		The nanogel was synthesized via emulsification-evaporation method and a microscopic molecular examination of the surface features of these systems and an evaluation of their cytocompatibility were also performed	Efficient drug delivery devices with prolonged sustained release	137
13	Polyethylene glycol (PEG) and polyethylene-imine (PEI) based nanogel coated with primary amines		The nanogel was synthesized by emulsification-evaporation method and experimental analysis indicated that activated astrocytes were more likely to be targeted by NG in vitro than microglia or neurons	Targeted delivery of rolipram to quench the pro-inflammatory effects mediated by astrocyte activation	138
14	Poly(ε-caprolactone)-b-poly(glycidyl methacrylate) (PCL-b-PGMA) block copolymers based nanogel		A combination of ring-opening polymerization and reversible addition–fragmentation chain transfer polymerization was implied for the synthesis of copolymers for nanogel production	Potential carrier for low molecular weight drugs	124
15	Poly-amino acid-based nanogel		Biodegradable and biocompatible cross-linked nanogels synthesized from polyglutamic acid ∼100 nm in size	Hydrophilic drug carriers for the chemotherapeutic agent doxorubicin for triple-negative breast cancer treatment	139
16	Anisotropic gold nanoparticles incorporated-polymeric thermoresponsive nanogel		Nanogel was thermoresponsive in nature and synthesized via click chemistry and thermo-nanoprecipitation with gold nanoparticles as the crosslinking agent	High NIR light-to-heat conversion efficiency for photothermal therapy	140
17	Photoresponsive oligonucleotide-based nanogel		The photoirradiation of nanogel led to hyperchromic shift at 260 nm and a simultaneous redshift of the absorption in the 350–400 nm region	Control of protein release via managing the dissociation of a protein's DNA complex	141
18	Thiacalix[4]arene functionalized chitosan-based nanogel (CS-g-TC4A)		The unique multifunctional nano adsorbent nanogel was an efficient sorption agent with controlled super-paramagnetic and sorption capabilities	The synthesized CS-g-TC4A nanogel having a triazole ring was used as an effective adsorbent for metal ions	142
19	Hyaluronan and riboflavin derivatives based nanohydrogel		The nanohydrogels formulation could be freeze-dried when dextrose was added as a cryoprotectant since they were extremely stable in water solutions	Drug carriers for the delivery of hydrophobic drugs	143
20	Thermoresponsive poly(N-vinylcaprolactam) nanogels functionalized with glucose and maltose		The nanogels were synthesized via semibatch precipitation polymerization which shrank upon heating and was equipped with a thermoresponsive structure and surface functionalities that allow for biorelevant interactions	Enhanced affinity for biomolecules due to the presence of carbohydrates results in greater potential for therapeutic uses as drug-delivery agents	144
21	Biodegradable dendritic polyglycerol nanogel		The dendritic polyglycerol nanogels were synthesized by inverse nanoprecipitation wherein the introduction of benzacetal bonds induced the biodegradability	Effective protein encapsulation and release among other biomacromolecules	145
22	Bisphosphonate ligand-functionalized dextran nanogel		Controlled functionalization of the nanogel with bisphosphonate ligand through astoichiometric click-chemistry in-emulsion method	Hepatic avoidance, binding to the bone on the inside of marrow cavities, and anti-osteoporotic actions	146
23	Alkynopoly(acrylic acid), diazido-poly(ethylene glycol), and diazido-poly(butylene succinate) based nanogel		Amphiphilicity of the nanogel is controlled via variations in the hydrophobic diazido-poly(butylene succinate) and the hydrophilic diazido-poly(ethylene glycol)	Interaction with multi-walled carbon nanotubes (MWCNTs), thereby acting as a potential dispersant of MWCNTs in hydrophilic media	147
24	Nanogel based on (adamantly (AD)-benzoic imine-conjugated poly [poly(ethylene glycol) monomethyl ether methacrylate]-co-poly(2-hydroxyethyl methacrylate) (PPEGMA-co-PHEMA-AD) as well as doxorubicin (DOX)-hydrazone and b-cyclodextrin(b-CD)		The polymeric nanogels were synthesized via host–guest interactions, for dual pH-triggered multistage drug delivery, and nanogels were reorganized into smaller nanoparticles in response to tumor acidity	Deep penetration of the drug at the tumor site, the release of doxorubicin in endosomal or lysosomal acidity (pH ∼5)	148
25	A pH and reduction dual-sensitive prodrug nanogel		The nanogel displayed excellent size stability against large-volume dilution, high salt concentration, and prolonged incubation in phosphate-buffered saline	Release doxorubicin in the intracellular acidic and reducible environment after being successfully absorbed by cancer cells	149