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Local delivery of anticancer agents via injectable hydrogels could be a promising method for achieving spatiotemporal control on drug release as well as minimizing the disadvantages related to the systemic mode of drug delivery. Keeping this in mind, we report the development of N,O-carboxymethyl chitosan (N,O-CMCS)–guar gum-based injectable hydrogels for the sustained delivery of anticancer drugs. The hydrogels were synthesized by chemical crosslinking of multialdehyde guar gum (MAGG) and N,O-CMCS through dynamic Schiff base linkages, without requiring any external crosslinker. Fabrication of injectable hydrogels, involving N,O-CMCS and MAGG via Schiff base crosslinking, is being reported for the first time. The hydrogels exhibited pH-responsive swelling behavior and good mechanical properties with a storage modulus of about 1625 Pa. Due to the reversible nature of Schiff base linkages, hydrogels displayed excellent self-healing and thixotropic properties. Doxorubicin (Dox), an anticancer agent, was loaded onto these hydrogels and its release studies were conducted at pH 7.4 (physiological) and pH 5.5 (tumoral). A sustained release of about 67.06% Dox was observed from the hydrogel after 5 days at pH 5.5 and about 32.13% at pH 7.4. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay on the human embryonic kidney cell line (HEK-293) and the hemolytic assay demonstrated the biocompatible nature of the hydrogels. The Dox-loaded hydrogel exhibited a significant killing effect against breast cancer cells (MCF-7) with a cytotoxicity of about 72.13%. All the data presented support the efficiency of the synthesized N,O-CMCS/MAGG hydrogel as a biomaterial that may find promising applications in anticancer drug delivery.

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Caffeinium-based surface-active ionic liquids (SAILs), (1-(2alkanoyl oxy) ethylcaffeinium bromide), [C n Ecaf]Br with variable chain length (n = 12, 14, 16) were synthesized and their molecular structures were explored by multiple spectral techniques. The critical micelle concentration (CMC) of pure SAILs and their mixtures with sodium dodecyl sulfate (SAIL-DS) in aqueous solution was determined by employing various techniques at 298 K. The tensiometry and dynamic light scattering (DLS) techniques have been employed to gain insight about the interfacial behavior and aggregate size of catanionic mixtures in aqueous solution. Interestingly, the interaction parameters (X m 1 ; b m ) showed strong synergism between these two oppositely charged molecules. Further, it was found that SAIL-DS cat-anionic mixtures exhibit excellent adsorption efficacy and are more effective in lowering the surface tension of water as compared to pure SAILs. The DLS results showed the formation of mixed-size aggregates in SAIL-DS systems. The contact angle and wetting properties of pure SAILs over the parafilm surface were also determined using a static sessile drop method. Further, MTT assay was used to determine the biocompatibility of SAILs on Human embryonic kidney (HEK-293) cell line and in-vitro anti-cancer activity on Lung cancer cells (A549). These SAILs displayed substantial cytotoxicity against cancerous cells, indicating that they could be useful in a variety of biological applications.

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