Nagaprasad Puvvada

The potential of celecoxib-loaded hydroxyapatite-chitosan nanocomposite for the treatment of colon cancer

Celecoxib has shown potential anticancer activity against most carcinomas, especially in patients with familial adenomatous polyposis and precancerous disease of the colon. However, serious side effects of celecoxib restrict its generalized use for cancer therapy. In order to resolve these issues and develop an alternative strategy/preliminary approach, chitosan modified hydroxyapatite nanocarriers-mediated celecoxib delivery represents a viable strategy. We characterized the nanoparticle for morphology, particle size, zeta potential, crystalinity, functional group analysis, entrapment efficiency, drug release and hemocompatibility. The effects of celecoxib-loaded nanoparticles on colon cancer cell proliferation, morphology, cytoskeleton, cellular uptake and apoptosis were analysed in vitro. Further, we evaluated the antiproliferative, apoptotic and tumor inhibitory efficacy of celecoxib-loaded nanocarriers in a nude mouse human xenograft model. Nanoparticles exhibited small, narrow hydrodynamic size distributions, hemocompatibility, high entrapment efficiencies and sustained release profiles. In vitro studies showed significant antiproliferation, apoptosis and time-dependent cytoplasmic uptake of celecoxib-loaded Hap-Cht nanoparticles in HCT 15 and HT 29 colon cancer cells. Additional in vivo studies demonstrated significantly greater inhibition of tumor growth following treatment with this modified nanoparticle system. The present study indicates a promising, effective and safe means of using celecoxib, and potentially other therapeutic agents for colon cancer therapy.

Synthesis of biocompatible multicolor luminescent carbon dots for bioimaging applications

Abstract Water-soluble carbon dots (C-dots) were prepared through microwave-assisted pyrolysis of an aqueous solution of dextrin in the presence of sulfuric acid. The C-dots produced showed multicolor luminescence in the entire visible range, without adding any surface-passivating agent. X-ray diffraction and Fourier transform infrared spectroscopy studies revealed the graphitic nature of the carbon and the presence of hydrophilic groups on the surface, respectively. The formation of uniformly distributed C-dots and their luminescent properties were, respectively, revealed from transmission electron microscopy and confocal laser scanning microscopy. The biocompatible nature of C-dots was confirmed by a cytotoxicity assay on MDA-MB-468 cells and their cellular uptake was assessed through a localization study.

Photoresponsive coumarin-tethered multifunctional magnetic nanoparticles for release of anticancer drug

Recently, photoresponsive nanoparticles have received significant attention because of their ability to provide spatial and temporal control over the drug release. In the present work, we report for the first time photoresponsive multifunctional magnetic nanoparticles (MNPs) fabricated using coumarin-based phototrigger and Fe/Si MNPs for controlled delivery of anticancer drug chlorambucil. Further, newly fabricated photoresponsive multifunctional MNPs were also explored for cell luminescence imaging. In vitro biological studies revealed that coumarin tethered Fe/Si MNPs of ~9 nm size efficiently delivered the anticancer drug chlorambucil into cancer cells and thereby improving the drug action to kill the cancer cells upon irradiation. Such multifunctional MNPs with strong fluorescence, good biocompatibility and efficient photocontrolled drug release ability will be of great benefit in the construction of light-activated multifunctional nano drug delivery systems.

Novel ZnO hollow-nanocarriers containing paclitaxel targeting folate-receptors in a malignant pH-microenvironment for effective monitoring and promoting breast tumor regression

Low pH in the tumor micromilieu is a recognized pathological feature of cancer. This attribute of cancerous cells has been targeted herein for the controlled release of chemotherapeutics at the tumour site, while sparing healthy tissues. To this end, pH-sensitive, hollow ZnO-nanocarriers loaded with paclitaxel were synthesized and their efficacy studied in breast cancer in vitro and in vivo. The nanocarriers were surface functionalized with folate using click-chemistry to improve targeted uptake by the malignant cells that over-express folate-receptors. The nanocarriers released ~75% of the paclitaxel payload within six hours in acidic pH, which was accompanied by switching of fluorescence from blue to green and a 10-fold increase in the fluorescence intensity. The fluorescence-switching phenomenon is due to structural collapse of the nanocarriers in the endolysosome. Energy dispersion X-ray mapping and whole animal fluorescent imaging studies were carried out to show that combined pH and folate-receptor targeting reduces off-target accumulation of the nanocarriers. Further, a dual cell-specific and pH-sensitive nanocarrier greatly improved the efficacy of paclitaxel to regress subcutaneous tumors in vivo. These nanocarriers could improve chemotherapy tolerance and increase anti-tumor efficacy, while also providing a novel diagnostic read-out through fluorescent switching that is proportional to drug release in malignant tissues.

Shape dependent peroxidase mimetic activity towards oxidation of pyrogallol by H2O2

Truncated octahedron shaped magnetite nanoparticles have been prepared via a chemical method and subsequently their shape dependent peroxidase mimetic activity has been verified using pyrogallol substrate. Their peroxidase mimetic activity has been found to be superior to that of spherical-shaped nanoparticles.

Overcoming Akt Induced Therapeutic Resistance in Breast Cancer through siRNA and Thymoquinone Encapsulated Multilamellar Gold Niosomes.

Akt overexpression in cancer causes resistance to traditional chemotherapeutics. Silencing Akt through siRNA provides new therapeutic options; however, poor in vivo siRNA pharmacokinetics impede translation. We demonstrate that acidic milieu-sensitive multilamellar gold niosomes (Nio-Au) permit targeted delivery of both Akt-siRNA and thymoquinone (TQ) in tamoxifen-resistant and Akt-overexpressing MCF7 breast cancer cells. Octadecylamine groups of functionalized gold nanoparticles impart cationic attribute to niosomes, stabilized through polyethylene glycol. TQs aqueous insolubility renders its encapsulation within hydrophobic core, and negatively charged siRNA binds in hydrophilic region of cationic niosomes. These niosomes were exploited to effectively knockdown Akt, thereby sensitizing cells to TQ. Immunoblot studies revealed enhanced apoptosis by inducing p53 and inhibiting MDM2 expression, which was consistent with in vivo xenograft studies. This innovative strategy, using Nio-Au to simultaneously deliver siRNA (devoid of any chemical modification) and therapeutic drug, provides an efficacious approach for treating therapy-resistant cancers with significant translational potential.

Aqueous route for the synthesis of magnetite nanoparticles under atmospheric air: functionalization of surface with fluorescence marker

A simple chemical precipitation approach has been established for the synthesis of magnetite nanoparticles under atmospheric air conditions. The process involves precipitation of Fe3O4 nanoparticles from an aqueous solution containing ferric chloride, hydrochloric acid, sodium sulphite, ammonium ferrous sulphate and ammonia. Further, these nanoparticles were surface conjugated with aminated silica for the attachment of rhodamine 610. The crystallinity was assessed by X-ray diffraction and surface conjugation of aminated silica confirmed by Fourier transform infrared spectroscopy and Electron probe micro-analyzer. Fluorescent absorption measurements revealed a red shift with surface conjugated rhodamine 610 magnetite nanoparticles in comparison to free rhodamine 610 mixed with aminated magnetic nanoparticles. The magnetic measurements of prepared samples showed superparamagnetism, which led us to investigate its usage in internalization studies for biomedical applications. The internalization study of the conjugated magnetite nanoparticles in cell by fluorescent microscopy at different time intervals recommends its usage as an efficient drug delivery system.