Natural cationic polymers-derived injectable hydrogels for targeted chemotherapy

Abstract

Streamflow is a vital component of the global water cycle. Long-term streamflow observations are required for water resources planning and management, hydroclimatic extremes analysis, and ecological assessment. However, long-term streamflow observations for the Indian-Subcontinental (ISC) river basins are lacking. Using meteorological observations, state-of-the-art hydrological model, and river routing model, we developed hydrological model-simulated monthly streamflow from 1951-2021 for the ISC river basins. We used high-resolution vector-based routing model (mizuRoute) to generate streamflow at 9579 stream reaches in the sub-continental river basins. The model-simulated streamflow showed good performance against the observed flow with coefficient of determination (R2) and Nash-Sutcliffe efficiency (NSE) above 0.70 for more than 60% of the gauge stations. The dataset was used to examine the variability in low, average, and high flow across the streams. Long-term changes in streamflow showed a significant decline in flow in the Ganga basin while an increase in the semi-arid western India and Indus basin. Long-term streamflow can be used for planning water management and climate change adaptation in the Indian sub-continent. Current therapeutics have been revolutionized with the future applications of injectable hydrogels. Therapeutic hydrogels exhibit distinctive physicochemical properties, including flexible porous structure, binding affinity for biological fluids, porous structural configuration, higher water content, high flexibility, biodegradability, and biocompatibility. These technologies have tremendously assisted in various clinical implications, specifically for the site-specific and sustained delivery of chemotherapeutic drugs. Drug-encapsulated injectable hydrogels showcase significant superiority over conventional therapeutics, such as minimized adverse effects, enhanced therapeutic efficacy, augmented pharmacological profile, and superior patient compliance. Conventional approaches mainly include intravenous chemotherapy, which can potentially cause adverse effects such as myelosuppression, nephro- or hepatic dysfunction, and neurotoxicity. The injectable hydrogel is a potent approach to overcome these impediments by releasing the chemotherapeutic drugs at the specific tumor sites after topical administration. Moreover, the therapeutic efficiency of cancer immunotherapy is majorly dependent upon the tumor microenvironment, which can be targeted with chemotherapeutic drugs-loaded injectable hydrogels for improved cancer therapy. In addition, natural cationic polymers such as chitosan, cyclodextrins, gelatin, cellulose, dextran, and others have endured substantial attention from investigators in drug delivery due to their easy obtainability, high encapsulation efficiency, improved bioavailability, sustained drug release properties, biodegradability, and biocompatibility. This review summarizes the mainstream approaches for synthesizing injectable hydrogels and the biological properties of different natural cationic polymers. We have also focused on the notable studies of cationic polymers used definitively to fabricate hydrogel-mediated systems for anticancer drug delivery. Further, the therapeutic approaches, molecular insights, pharmacological actions, and clinical significance have been discussed.