Pseudomonas aeruginosa is a leading opportunistic pathogen and its expanding drug resistance is a growing menace to public health. Its ubiquitous nature and multiple resistance mechanisms make it a difficult target for antimicrobial chemotherapy and require a fresh approach for developing new antimicrobial agents against it. The broad-spectrum antibacterial effects of silver nanoparticles (SNPs) make them an excellent candidate for use in the medical field. However, attempts made to check their potency against extensively drug-resistant (XDR) microbes are meager. This study describes the biosynthesis and biostabilization of SNPs by Helicteres isora aqueous fruit extract and their characterization by ultraviolet-visible spectroscopy, transmission electron microscopy, dynamic light scattering, X-ray diffraction, and Fourier transform infrared spectroscopy. Majority of SNPs synthesized were of 8--20-nm size. SNPs exhibited dose-dependent antibacterial activities against four XDR P. aeruginosa (XDR-PA) clinical isolates as revealed by growth curves, with a minimum inhibitory concentration of 300 μg/ml. The SNPs exhibited antimicrobial activity against all strains, with maximum zone of inhibition (16.4 mm) in XRD-PA-2 at 1000 μg/ml. Amongst four strains, their susceptibilities to SNPs were in the following order: XDR-PA-2 > XDR-PA-4 > XDR-PA-3 > XDR-PA-1. The exposure of bacterial cells to 300 μg/ml SNPs resulted into a substantial leakage of reducing sugars and proteins, inactivation of respiratory chain dehydrogenases, and eventual cell death. SNPs also induced lipid peroxidation, a possible underlying factor to membrane porosity. The effects were more pronounced in XDR-PA-2 which may be correlated with its higher susceptibility to SNPs. These results are indicative of SNP-induced turbulence of membranous permeability as an important causal factor in XDR-PA growth inhibition and death.

Phosphatidylinositol-3-kinase (PI3K) signaling has been hijacked in different types of cancers. Hence, PI3K inhibitors have emerged as novel targeted therapeutics in cancer treatment as mono and combination therapy along with other DNA damaging drugs. However, targeting PI3K signaling with small molecules leads to the emergence of drug resistance and severe side effects to the cancer patients. To address these, we have developed a biocompatible, biodegradable cholesterol-based chimeric nanoparticle (CNP), which can simultaneously load PI103, doxorubicin, and cisplatin in a controlled ratiometric manner. Size, shape, and morphology of these CNPs were characterized by dynamic light scattering (DLS), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). Increased amounts of PI103, doxorubicin, and cisplatin were released from CNPs through controlled and continuous manner over 120 h at pH = 5.5 compared to neutral pH. The CNPs showed much enhanced in vitro cytotoxicity in HeLa, HL60, MCF7, and MDA-MB-231 cancer cells compared to a free drug cocktail at 24 and 48 h by inducing apoptosis. Confocal laser scanning microscopy (CLSM) imaging revealed that indeed these CNPs were internalized into subcellular lysosomes through endocytosis in a time dependent mode over 6 h and retained inside for 48 h in HeLa, MDA-MB-231, and MCF7 cells. These CNPs showed their efficacy by damaging DNA and inhibiting Akt as a downstream modulator of PI3K signaling in HeLa cervical cancer cells. These CNPs have the potential to open up new directions in next-generation nanomedicine by simultaneous targeting of multiple oncogenic signaling pathways and inducing DNA damage for augmented therapeutic outcome by reducing toxic side effects and overcoming drug resistance.

Overcoming drug resistance is one of the most challenging problems in cancer chemotherapy. Drug cocktails can overcome the drug resistance. However, multiple drug combinations lead to multifold increment of off-target toxicity, as well as the delivery of the required therapeutic amount of combined drugs remains problematic. To address these problems, we have developed a sub 200 nm vitamin D3 nanoparticle, which can contain a rational combination of dual drugs (PI103 and cisplatin or doxorubicin or proflavine). The size, shape and morphology of these dual drug containing vitamin D3 nanoparticles were characterized by DLS, FESEM, AFM and TEM. The nanoparticles released the dual drugs in high quantity at pH ¼ 5.5 compared to pH ¼ 7.4 in a slow and sustained manner over 72 h with stability over 15 days at 37 C, as well as 4 C. These dual drug loaded nanoparticles induced increased cell death in human hepatocellular carcinoma, Hep3B cells at 24 h compared to monotherapy; moreover, they were effective against cisplatin-resistant cells (Hep3B-R) as well. VitD3-PI103-CDDP-NP and vitD3-PI103-Dox-NP showed cytotoxicity by inducing apoptosis through DNA damage. Furthermore, vitD3-PI103-CDDP-NP showed considerably improved efficacy in 5-fluorouracil (5-FU) resistant Hep3B-5FU-R cells; its activity was even better compared to 5-FU. Finally, vitD3-PI103-proflavine-NP internalized into Hep3B-R cells considerably faster (within 3 minutes) compared to Hep3B cells, as visualized by fluorescent microscopy. Therefore, these dual drug loaded nanoparticles can successfully overcome the trauma of drug resistance and have the potential to be applied into the clinics for improved cancer therapeutics.

Mitogen‐activated protein kinase (MAPK) signaling has been dysregulated in different types of cancers. However, targeting MAPK signaling with small molecules leads to severe toxic side effects to the patients as well as manifestation of drug resistance. To address these, we have developed 120 nm sized self‐assembled, biocompatible, biodegradable oleic acid nanoparticles (OA‐NPs) which can simultaneously contain AZD6244 (MAPK inhibitor) and cisplatin (DNA damaging drug). These OA‐NPs released AZD6244 and cisplatin in increased amount in pH 5.5 compared to pH 7.4 in a slow and sustained manner over 4 days with excellent stability at 4 °C for 2 months in water and in blood circulation mimic for 6 days. Moreover, these OA‐NPs showed much improved in vitro cytotoxicity in cervical cancer (HeLa) and triple negative breast cancer (MDA‐MB‐231) cells at 48 h and in hepatocellular carcinoma (Hep3B) and cisplatin‐resistant hepatocellular carcinoma (Hep3B‐R) cells at 24 h. In HeLa cells, these OA‐NPs induced apoptosis through inhibiting MAPK signaling and damaging DNA after being internalized through macropinocytosis and homed into the acidic lysosomal compartments. These OA‐NPs have the potential to be translated into the clinic for targeting multiple oncogenic signaling pathways and damaging DNA concurrently for augmented efficacy, reduced toxicity, and overcoming drug resistance in next‐generation cancer treatment.