Chitosan hydrogel covalently crosslinked by gold nanoparticle: Eliminating the use of toxic crosslinkers

Abstract

Tissue engineering has directed a lot of effort toward the development of devices with suitable biocompatibility and mechanical properties. Chitosan has been pointed as a valuable material to be applied in scaffolds due to its antimicrobial activity and biocompatibility. Nevertheless, the low mechanical resistance associated with the requirement of toxic crosslinkers has hampered translational application of chitosan hydrogel. Herein, the use of gold nanoparticles (AuNP) as crosslinker is reported as a great strategy to obtain chitosan hydrogel without using toxic reactants. In addition, the resultant chitosan hydrogel, crosslinked by AuNP of 30 nm (AuNP30), presented outstanding properties compared to chitosan hydrogel crosslinked by glutaraldehyde. Chitosan hydrogel crosslinked by AuNP30 presented lower porosity, which provided lower swelling degree and slower degradation rate. In addition, compressive strength was about two times higher than the chitosan hydrogel crosslinked by glutaraldehyde. The crosslink by AuNP30 also increased the biocompatibility of the hydrogel. Chitosan hydrogel crosslinked by AuNP30 did not show cytotoxicity against MEF cells, whereas cell viability of cells incubated with extract from chitosan hydrogel crosslinked by glutaraldehyde was only 41%. In conclusion, the results reported herein pointed that the use of AuNP30 as crosslinker agent provided to chitosan hydrogel enhanced properties that made it suitable to application in biomedical devices.

Fabrication and Comparative Quantitative Analysis of Plasmonic-Polymer Nanocomposites as Optical Platforms

“…A wide range of plasmonic-polymer nanocomposites has been developed by combining AuNPs or AgNPs and polymers such as agarose, chitosan, and poly­(methyl methacrylate) (PMMA) for SERS-based optical sensing, imaging, and photothermal applications. ,− Plasmonic-polymer nanocomposites can synergistically benefit from the excellent optical properties of plasmonic NPs and the wide range of mechanical and chemical properties of polymers, rendering various functionalities. , For instance, plasmonic nanocomposites of macroporous poly- N -isopropylacrylamide (pNIPAM) hydrogel loaded with gold nanorods have been used as biocompatible, SERS substrates for label-free in situ probing of quorum sensing in biofilms . Chitosan complexed with plasmonic NPs have been widely used as biocompatible optical substrates due to their excellent biocompatibility, biodegradability, and non-toxicity. ,,− Xu et al . have developed stable and biocompatible Raman-active probes by coating gold nanoflowers (AuNFs) with chitosan and demonstrated their potential for targeting tumors in vivo .…”

Dynamic protein and polypeptide hydrogels based on Schiff base co-assembly for biomedicine

“…38 Hydrazide/carbodiimide coupling and regioselective oxidation of glycols are the most common one-pot routes to functional modification, as aldehyde crosslinkers are cytotoxic and may dissociate from the hydrogels under physiological conditions. 66 Periodate oxidation is best suited to functionalise polysaccharides with accessible vicinal diols, while hydrazide/carbodiimide coupling can also be used to functionalise amino and carboxylic acid residues in biopolymers. If aldehyde crosslinkers are to be used, dialdehyde crosslinkers such as glutaraldehyde may be added directly to the hydrogel mixture as they can form two imine bonds with oxidised polysaccharides, while mono-aldehydes, such as benzaldehyde and formaldehyde, can be appended as pendants to polymers such as polyethylene glycol (PEG).…”

Mechanical Properties of Bioengineered Corneal Stroma

“…Collagen cross-linking increases stiffness and tensile stress, however, it comes with a reduced biocompatibility and possible toxicity of remnant cross-linking agents. [100][101][102] For these types of solutions, the main challenge is finding a reasonable balance between mechanostability and biocompatibility during the first months after implantation, so that residing keratocytes are able to effectively re-establish a healthy ECM.…”

“…Hence, it is not ideal for the production of engineered corneal implants. [100,101] An alternative is genipin, a chemical cross-linker of natural origin that can form both inter-and intramolecular cross-links in collagen fibrils. in vitro, genipin has shown to be a successful cross-linker in collagen type I hydrogels, increasing storage and loss moduli by a factor of 15 and 4.5, respectively.…”