Mesoporous Zn_yCd_1-yS quantum dots (QDs) with mixed cubic–hexagonal phases prepared by sonochemical technique at varying Zn content. Incorporating Zn ions in the CdS lattice reduced the crystalline size and enhanced the corresponding surface areas at increasing Zn contents. The increase of Zn content in Zn_yCd_1-yS QDs increased the bandgap from 2.52 eV to 3.83 eV and enhanced the corresponding Urbach energy from 72 meV to 279 meV. Zn_yCd_1-yS QDs exhibited small electrical activation energies ranging from 249 mV to 361 mV. The effect of Zn content on the catalytic activity of Zn_yCd_1-yS QDs toward hydrogen production through NaBH₄ hydrolysis was investigated at different temperatures. Ternary alloys ZnCdS QDs exhibited higher catalytic activity than pure ZnS and CdS QDs, with Zn_0.5Cd_0.5S QDs displaying the highest hydrogen generation rate of 96 mL∙min⁻¹∙g⁻¹. The increase of reaction temperature from 30°C to 60°C enhanced the rate constant of hydrogen production from 0.071 to 0.36 min⁻¹. Based on the pseudo-first-order equation, the estimated apparent activation energy of Zn_0.5Cd_0.5S QDs was 45.3 kJ∙mol⁻¹. Overall, the obtained results underscored the potential of Zn_yCd_1-yS QDs as promising catalysts for hydrogen generation.

Metronomic chemotherapy (MC), long-term continuous administration of anticancer drugs, is gaining attention as an alternative to the traditional maximum tolerated dose (MTD) chemotherapy. By combining MC with other treatments, the therapeutic efficacy is enhanced while minimizing toxicity. MC employs multiple mechanisms, making it a versatile approach against various cancers. However, drug resistance limits the long-term effectiveness of MC, necessitating ongoing development of anticancer drugs. Traditional drug discovery is lengthy and costly due to processes like target protein identification, virtual screening, lead optimization, and safety and efficacy evaluations. Drug repurposing (DR), which screens FDA-approved drugs for new uses, is emerging as a cost-effective alternative. Both experimental and computational methods, such as protein binding assays, in vitro cytotoxicity tests, structure-based screening, and several types of association analyses (Similarity-Based, Network-Based, and Target Gene), along with retrospective clinical analyses, are employed for virtual screening. This review covers the mechanisms of MC, its application in various cancers, DR strategies, examples of repurposed drugs, and the associated challenges and future directions.