Fundamental Concepts of Hydrogels: Synthesis, Properties, and Their Applications

In the present review, we focused on the fundamental concepts of hydrogels-classification, the polymers involved, synthesis methods, types of hydrogels, properties, and applications of the hydrogel. Hydrogels can be synthesized from natural polymers, synthetic polymers, polymerizable synthetic monomers, and a combination of natural and synthetic polymers. Synthesis of hydrogels involves physical, chemical, and hybrid bonding. The bonding is formed via different routes, such as solution casting, solution mixing, bulk polymerization, free radical mechanism, radiation method, and interpenetrating network formation. The synthesized hydrogels have significant properties, such as mechanical strength, biocompatibility, biodegradability, swellability, and stimuli sensitivity. These properties are substantial for electrochemical and biomedical applications. Furthermore, this review emphasizes flexible and self-healable hydrogels as electrolytes for energy storage and energy conversion applications. Insufficient adhesiveness (less interfacial interaction) between electrodes and electrolytes and mechanical strength pose serious challenges, such as delamination of the supercapacitors, batteries, and solar cells. Owing to smart and aqueous hydrogels, robust mechanical strength, adhesiveness, stretchability, strain sensitivity, and self-healability are the critical factors that can identify the reliability and robustness of the energy storage and conversion devices. These devices are highly efficient and convenient for smart, light-weight, foldable electronics and modern pollution-free transportation in the current decade.

Superfluorinated PEI Derivative Coupled with (99m) Tc for ASGPR Targeted (19) F MRI/SPECT/PA Tri-Modality Imaging

Fluorinated polyethylenimine derivative labeled with radionuclide (99m) Tc is developed as a (19) F MRI/SPECT/PA multifunctional imaging agent with good asialoglycoprotein receptors (ASGPR)-targeting ability. This multifunctional agent is safe and suitable for (19) F MRI/SPECT/PA imaging and has the potential to detect hepatic diseases and to assess liver function, which provide powerful support for the development of personalized and precision medicine.

Asialoglycoprotein receptor-magnetic dual targeting nanoparticles for delivery of RASSF1A to hepatocellular carcinoma

We developed a nanovector with double targeting properties for efficiently delivering the tumor suppressor gene RASSF1A specifically into hepatocellular carcinoma (HCC) cells by preparing galactosylated-carboxymethyl chitosan-magnetic iron oxide nanoparticles (Gal-CMCS-Fe₃O₄-NPs). After conjugating galactose and CMCS to the surface of Fe₃O₄-NPs, we observed that Gal-CMCS-Fe₃O₄-NPs were round with a relatively stable zeta potential of +6.5 mV and an mean hydrodynamic size of 40.1 ± 5.3 nm. Gal-CMCS-Fe₃O₄-NPs had strong DNA condensing power in pH 7 solution and were largely nontoxic. In vitro experiments demonstrated that Gal-CMCS-Fe₃O₄-NPs were highly selective for HCC cells and liver cells. In vivo experiments showed the specific accumulation of Gal-CMCS-Fe₃O₄-NPs in HCC tissue, especially with the aid of an external magnetic field. Nude mice with orthotopically transplanted HCC received an intravenous injection of the Gal-CMCS-Fe₃O₄-NPs/pcDNA3.1(+)RASSF1A compound and intraperitoneal injection of mitomycin and had an external magnetic field applied to the tumor area. These mice had the smallest tumors, largest percentage of TUNEL-positive cells, and highest caspase-3 expression levels in tumor tissue compared to other groups of treated mice. These results suggest the potential application of Gal-CMCS-Fe₃O₄-NPs for RASSF1A gene delivery for the treatment of HCC.

N-succinyl chitosan preparation, characterization, properties and biomedical applications: a state of the art review

N-succinyl chitosan (NSC) remains a promising chitosan derivative to develop targeted drug delivery, wound dressings, and tissue engineering systems. All these systems are important in life sciences. NSC is an amphiprotic derivative obtained from the N-acylation of chitosan. NSC exhibits extraordinary biocompatibility, significantly increased aqueous solubility in acidic and basic media without affecting the biological properties, appreciable transfection efficiency, and the ability to stimulate osteogenesis. NSC shows enhanced bioavailability, which highlights its potential applications in the biomedical field. This review briefly introduces chitosan, including its limitations as a biomaterial, and modifications of chitosan with a particular focus on acylation, along with a comprehensive overview of the synthesis, characterization, properties, biodistribution, and toxicological/biopharmaceutical profile of NSC. Furthermore, it extensively surveys current state-of-the-art NSC-based formulations for drug delivery with special emphasis on protein delivery, anti-cancer activity in the colon, as well as nasal and ophthalmic targeted gene/drug delivery. Moreover, it discusses NSC-based biomaterial applications in articular, adipose, and bone tissue engineering. In addition, it describes recent contributions of NSC-based hydrogels in wound dressings along with a brief account of drug delivery in combination with tissue engineering. Finally, it presents potential current challenges and future perspectives of NSC-based formulations in the biomedical field.

A self-assembling polycationic nanocarrier that exhibits exceptional gene transfection efficiency

A novel polycationic gene carrier was prepared by conjugation of low molecular weight polyethyleneimine with gelatin through 4-bromonaphthaleic anhydride with exceptionally high transfection efficiency.

Arginine functionalized peptide dendrimers as potential gene delivery vehicles

The quest for highly efficient and safe gene delivery systems has become the key factor for successful application of gene therapy. Peptide dendrimers are currently investigated as excellent candidates for non-viral gene delivery vectors. In this study, we report the synthesis and characterization of arginine functionalized peptide dendrimer-based vectors ranging from 5th generation (G5A) to 6th generation (G6A) via click chemistry, and their use for gene transfection in vitro and in vivo. The dendrimers can condense plasmid DNA (pDNA) and protect pDNAs from nuclease digestion. Both atomic force microscopy (AFM) and dynamic light scattering (DLS) revealed that the sizes of dendrimer/DNA particles were within 180-250 nm range. In vitro studies showed that the functionalized peptide dendrimers provided serum independent and high transfection efficiency on all studied cells, as over 2 fold higher than that of branched polyetherimide (PEI) in the presence of serum. Dendrimer G5A with molecular weight of 17 kDa demonstrated 6-fold transfection activity than PEI in breast tumor models, as well as good biosafety proved by in vitro and in vivo toxicity evaluation. However, G6A with molecular weight of 46 kDa showed much higher cytotoxicity. The functionalized dendrimer G5A with optimal generation may be therefore a potential candidate for gene delivery vehicle.

Design and synthesis of dual-ligand modified chitosan as a liver targeting vector

Vector plays an important role in hepatic targeted drug delivery system. In this study, a novel material as a liver targeting vector, dual-ligand modified chitosan (GCGA) composed of chitosan (CTS), glycyrrhetinic acid (GA) and lactobionic acid (LA), was designed and synthesized by an orthogonal experiment with two-step synthesis under mild conditions. The synthesized final product was characterized and confirmed by FTIR and (1)H-NMR spectroscopy, and DS of GA and LA in CTS were measured to be 13.77 and 16.74 mol% using (1)H-NMR, respectively. The cytotoxicity of CTS and GCGA was concentration dependent which was inverse proportion to the cell viability by MTT assay using L929 cell line, and inhibitory concentration 50% (IC50) was 0.2 mg/ml for GCGA. The in vitro targeting efficiency and the in vitro cellular uptake were investigated. Compared with CTS NPs and GA-CTS NPs, GCGA NPs showed good cell specificity to BEL-7402 cells via the dual-ligand-receptor-mediated recognition, leading to a higher affinity to BEL-7402 cells. The results suggested that GCGA described here has the potential to be used as an effective vector for hepatic targeted drug therapy.