Curcumin as a green fluorescent label to revive the fluorescence property of functionalized graphene oxide nanosheets

Platin-C containing nanoparticles: a recipe for the delivery of curcumin-cisplatin combination chemotherapeutics to mitochondria

The success story of cisplatin spans over six decades now and yet it continues to be the key player in most chemotherapeutic regimens. Numerous efforts have been made to improve its efficacy, address its shortcomings, and overcome drug resistance. One such strategy is to develop new platinum(IV)-based prodrugs with functionally active ligands to deliver combination therapeutics. This strategy not only enables the drug candidate to access multiple drug targets but also enhances the kinetic inertness of platinum complexes and thereby ensures greater accumulation of active drugs at the target site. We report the synthesis of Platin-C, a platinum(IV)-based cisplatin prodrug tethered to the active component of ancient herbal medicine, curcumin, as one of the axial ligands. This combination complex showed improved chemotherapeutic efficacy in cisplatin resistant A2780/CP70 cell lines compared with the individual components. An amine-terminated biodegradable polymer was suitably functionalized with the triphenylphosphonium (TPP) cation to obtain a mitochondria-directed drug delivery platform. Quantification of Platin-C loading into these NPs using complementary techniques employing curcumin optical properties in high-performance liquid chromatography and platinum-based inductively coupled plasma mass spectrometry evidenced efficacious payload incorporation resulting in functional activities of both the components. Stability studies for a period of one week indicated that the NPs remain stable, enabling substantial loading and controlled release of the prodrug. The targeting nanoparticle (NP) platform was utilized to deliver Platin-C primarily in the mitochondrial network of cancer cells as monitored using confocal microscopy employing the green fluorescence of the curcumin pendant. Our studies showed that amine terminated NPs were relatively less efficient in their ability to target mitochondria despite being positively charged. This re-validated the importance of lipophilic positively charged TPP surface functionalities to successfully target cellular mitochondria. We validated the capabilities of Platin-C and its mitochondria-targeting nanoparticles towards inflicting mitochondria-directed activity in cisplatin-sensitive and cisplatin-resistant cell lines. Furthermore, our studies also demonstrated the effectiveness of Platin-C incorporated targeting NPs in attenuating cellular inflammatory markers by utilizing the curcumin component. This study advances our understanding of the cisplatin prodrug approach to combine chemotherapeutic and inflammatory effects in accessing combinatory pathways.

NiO nanocomposites/rGO as a heterogeneous catalyst for imidazole scaffolds with applications in inhibiting the DNA binding activity

Herein, we report a facile approach to synthesize a new highly versatile heterogeneous catalyst by spontaneous aerial oxidation based on nickel oxide nanocomposites immobilized on surface-functionalized reduced graphene oxide sheets. NiO nanocomposite/reduced graphene oxide (rGO-NiO-NC) is a highly efficient, cost-effective, reusable, selective, and eco-friendly nano-catalyst that does not lose any activity even after five reaction cycles. Nickel loading on the rGO-NiO nanocomposite was found to be 3.3 at%, which contributes to the effective and efficient use of rGO-NiO-NCs as a nano-catalyst for the synthesis of imidazole derivatives. Consequently, a series of imidazole derivatives were synthesized, catalyzed by rGO-NiO-NCs, in 60 min with high yields (86% to 96%) under green conditions. Furthermore, the present synthetic methodology was used for the synthesis of highly aromatic imidazole derivatives (B1-B3) whose calf thymus-DNA binding affinities suggest their superior inhibition ability to displace ethidium bromide (EB), which was further confirmed by molecular docking studies. Additionally, the green chemistry matrix of the synthesis reaction was found to be very close to ideal values, such as carbon efficiency (82.32%), E-factor (0.51), atom economy (77.86%), process mass intensity (1.51), and reaction mass efficiency (66.14%).