Hitesh Kulhari

Xanthan gum stabilized gold nanoparticles: Characterization, biocompatibility, stability and cytotoxicity

Xanthan gum (XG) has been widely used in food, pharmaceutical and cosmetic industries. In the present study, we explored the potential of XG in the synthesis of gold nanoparticle. XG was used as both reducing and stabilizing agent. The effect of various formulation and process variables such as temperature, reaction time, gum concentration, gum volume and gold concentration, in GNP preparation was determined. The XG stabilized, rubey-red XGNP were obtained with 5 ml of XG aqueous solution (1.5 mg/ml). The optimum temperature was 80°C whereas the reaction time was 3 h. The optimized nanoparticles were also investigated as drug delivery carrier for doxorubicin hydrochloride. DOX loaded gold nanoparticles (DXGP) were characterized by dynamic light scattering, TEM, FTIR, and DSC analysis. The synthesized nanoparticle showed mean particle size of 15-20 nm and zeta potential -29.1 mV. The colloidal stability of DXGP was studied under different conditions of pH, electrolytes and serum. Nanoparticles were found to be stable at pH range between pH 5-9 and NaCl concentration up to 0.5 M. In serum, nanoparticles showed significant stability up to 24h. During toxicity studies, nanoparticles were found biocompatible and non-toxic. Compared with free DOX, DXGP displayed 3 times more cytotoxicity in A549 cells. In conclusion, this study provided an insight to synthesize GNP without using harsh chemicals.

Performance evaluation of PAMAM dendrimer based simvastatin formulations

The purpose of this investigation was to evaluate the performance of poly (amidoamine) (PAMAM) dendrimers, with three different surface groups, to be used as drug carriers. Drug-dendrimers complexes were investigated for solubility studies, dissolution studies, in vitro drug release studies, and for stability studies. The solubility enhancement was found maximum with PEGylated dendrimers (33 times) followed by amine (23 times) and hydroxyl (17.5 times) dendrimers. The solubility profile of simvastatin-dendrimer complex showed a linear correlation (Higuchi A(L)-type diagram) between solubility and dendrimers concentration. The formation of the complexes between drug molecules and dendrimers were characterized by the FTIR spectra of these complexes, showing the appearance of the bond formed between the functional groups of the drug (OH and COOH) and dendrimers (NH(2) and OH). The drug-dendrimer complexes displayed the controlled release action during in vitro release studies. Pure simvastatin (SMV) was released in 5h whereas the PEGylated dendrimers-SMV complexes released the drug up to 5 days. The non-PEGylated formulations released the drug up to 24h. Formulations with amine and PEGylated dendrimers were subjected to accelerated stability studies. Formulations with amine dendrimers were found to be most stable in dark, low temperature (0°C) whereas the dark, RT was most suitable storage conditions for formulation with PEGylated dendrimers.

Dendrimer-TPGS mixed micelles for enhanced solubility and cellular toxicity of taxanes

Taxanes are the most effective, efficient and broad spectrum anticancer drugs for the treatment of various cancers. However, poor aqueous solubility is the major problem in their delivery at higher concentrations in cancer cells. In this research work, poor solubility of taxanes is addressed by preparing dendrimer and d-α-tocopherol polyethylene glycol succinate (TPGS) mixed micelles by taking into consideration the advantages of TPGS such as solubility enhancement and P-glycoprotein inhibition. Dendrimer-TPGS mixed micelles were prepared by solvent casting method. Docetaxel (DTX) and paclitaxel (PTX) were chosen as model drugs representing the group of taxanes. Nanomicelles were characterized by DLS, FTIR, PXRD, in vitro drug release and hemolytic studies. Effects of pH and dendrimer to TPGS ratio on the solubility of taxanes were also studied. Solubility of DTX and PTX were increased by 20.36 and 34.95 folds, respectively, when formulated in dendrimer-TPGS mixed micelles. Drug release studies exhibited better release profile of encapsulated drug at acidic pH which is advantageous in enhanced intracellular drug release in cancer cells. Formulations were found to be biocompatible in hemolytic toxicity assay. Cytotoxicity studies revealed that anticancer activities of both drugs were enhanced after encapsulation in micelles against cancer cells while caused very low toxicity to normal cells. Thus, dendrimer-TPGS mixed micelles are promising alternate for delivery of poorly water-soluble drugs taxanes.

Peptide conjugated polymeric nanoparticles as a carrier for targeted delivery of docetaxel

The aim of this research work was to develop Bombesin peptide (BBN) conjugated, docetaxel loaded nanocarrier for the treatment of breast cancer. Docetaxel loaded nanoparticles (DNP) were prepared by solvent evaporation method using sodium cholate as surfactant. BBN was conjugated to DNP surface through covalent bonding. Both DNP and BBN conjugated DNP (BDNP) were characterized by various techniques such as dynamic light scattering, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and thermogravimetric analysis. The particle diameter and zeta potential of BDNP were 136±3.95 nm and -10.8±2.7 mV, respectively. The change in surface charge and FTIR studies confirmed the formation of amide linkage between BBN and DNP. AFM analysis showed that nanoparticles were spherical in shapes. In nanoparticles, docetaxel was present in its amorphous form as confirmed by DSC and PXRD analysis and was stable during the thermal studies. The formulations showed the sustained release of DTX over the period of 120 h. During cellular toxicity assay in gastrin releasing peptide receptor positive breast cancer cells (MDA-MB-231), BDNP were found to be 12 times more toxic than pure DTX and Taxotere. The IC50 value for DTX, Taxotere, DNP and BDNP was >375, >375, 142.23 and 35.53 ng/ml, respectively. The above studies showed that Bombesin conjugated nanocarrier system could be a promising carrier for active targeting of anticancer drugs in GRP receptor over expressing cancer cells.

Natural polysaccharide functionalized gold nanoparticles as biocompatible drug delivery carrier

Biocompatibility is one of the major concerns with inorganic nanoparticles for their applications as drug delivery system. Natural compounds such as sugars, hydrocolloids and plant extracts have shown potential for the green synthesis of biocompatible gold nanoparticles. In this study, we report the synthesis of gum karaya (GK) stabilized gold nanoparticles (GKNP) and the application of prepared nanoparticles in the delivery of anticancer drugs. GKNP were characterized using different analytical techniques. GKNP exhibited high biocompatibility during cell survival study against CHO normal ovary cells and A549 human non-small cell lung cancer cells and during hemolytic toxicity studies. Gemcitabine hydrochloride (GEM), an anticancer drug, was loaded on the surface of nanoparticles with 19.2% drug loading efficiency. GEM loaded nanoparticles (GEM-GNP) showed better inhibition of growth of cancer cells in anti-proliferation and clonogenic assays than native GEM. This effect was correlated with higher reactive oxygen species generation by GEM-GNP in A549 cells than native GEM. In summary, GK has significant potential in the synthesis of biocompatible gold nanoparticles that could be used as prospective drug delivery carrier for anticancer drugs.

Optimization of carboxylate-terminated poly(amidoamine) dendrimer-mediated cisplatin formulation.

Abstract Cisplatin is mainly used in the treatment of ovarian, head and neck and testicular cancer. Poor solubility and non-specific interactions causes hurdles in the development of successful cisplatin formulation. There were few reports on poly(amidoamine) (PAMAM) dendrimer–cisplatin complexes for anticancer treatment. But the earlier research was mainly focused on therapeutic effect of PAMAM dendrimer–cisplatin complex, with less attention paid on the formulation development of these complexes. Objective of the present study is to optimize and validate the carboxylate-terminated, EDA core PAMAM dendrimer-based cisplatin formulation with respect to various variables such as dendrimer core, generation, drug entrapment, purification, yield, reproducibility, stability, storage and in-vitro release. Dendrimer–cisplatin complex was prepared by an efficient method which significantly increases the % platinum (Pt) content along with the product yield. Dendrimers showed reproducible (∼27%) platinum loading by weight. Variation in core and generations does not produce significant change in the % Pt content. Percentage Pt content of dendrimeric formulation increases with increase in drug/dendrimer mole ratio. Formulation with low drug/dendrimer mole ratio showed delayed release compared to the higher drug/dendrimer mole ratio; these dendrimer formulations are stable in room temperature. In vitro release profiles of the stored dendrimer–cisplatin samples showed comparatively slow release of cisplatin, which may be due to formation of strong bond between cisplatin and dendrimer. This study will contribute to create a fine print for the formulation development of PAMAM dendrimer–cisplatin complexes.

Trastuzumab-grafted PAMAM dendrimers for the selective delivery of anticancer drugs to HER2-positive breast cancer

Approximately 20% of breast cancer cases are human epidermal growth factor receptor 2 (HER2)-positive. This type of breast cancer is more aggressive and tends to reoccur more often than HER2-negative breast cancer. In this study, we synthesized trastuzumab (TZ)-grafted dendrimers to improve delivery of docetaxel (DTX) to HER2-positive breast cancer cells. Bioconjugation of TZ on the surface of dendrimers was performed using a heterocrosslinker, MAL-PEG-NHS. For imaging of cancer cells, dendrimers were also conjugated to fluorescein isothiocyanate. Comparative in vitro studies revealed that these targeted dendrimers were more selective, and had higher antiproliferation activity, towards HER2-positive MDA-MB-453 human breast cancer cells than HER2-negative MDA-MB-231 human breast cancer cells. When compared with unconjugated dendrimers, TZ-conjugated dendrimers also displayed higher cellular internalization and induction of apoptosis against MDA-MB-453 cells. Binding of TZ to the dendrimer surface could help site-specific delivery of DTX and reduce systemic toxicity resulting from its lack of specificity. In addition, in vivo studies revealed that the pharmacokinetic profile of DTX was significantly improved by the conjugated nanosystem.

Cyclic-RGDfK peptide conjugated succinoyl-TPGS nanomicelles for targeted delivery of docetaxel to integrin receptor over-expressing angiogenic tumours

UNLABELLED Docetaxel (DTX) is an anticancer drug that is used alone and in combination with other drugs to treat tumours. However, it suffers from the drawback of non-specific cytotoxicity. To improve the therapeutic potential of DTX, we report the synthesis of cRGDfK peptide-conjugated succinoyl-TPGS (tocopheryl polyethylene glycol succinate) nanomicelles for targeted delivery of DTX. Among RGD (Arg-Gly-Asp) peptides, cRGDfK peptide shows specificity towards αvβ3 integrin receptors that are most commonly over-expressed in tumour cells. To cRGDfK peptide, succinoylated TPGS was synthesised and conjugated to cRGDfK peptide using a carbodiimide reaction. Peptide-conjugated DTX loaded nanomicelles (PDNM) displayed small particle size with a narrow distribution, controlled drug release and high physicochemical stability. Cytotoxicity, cellular uptake, apoptosis and anti-angiogenic comparisons of unconjugated nanomicelles to PDNM in DU145 human prostate cancer cells and HUVECs (Human Umblical Vein Endothelial Cells) clearly revealed the importance of the cRGDfK peptide in enhancing the drug delivery performance of nanomicelles. FROM THE CLINICAL EDITOR Common to many chemotherapeutic agents for cancer, systemic toxicity remains a big concern. In this article, the authors attempted to address this issue by conjugating RGD based peptides to Docetaxel, which would target integrins expressed on tumor cell surface. The experimental data revealed enhanced drug delivery.

Encapsulation of biophenolic phytochemical EGCG within lipid nanoparticles enhances its stability and cytotoxicity against cancer.

Epigallocatechin gallate (EGCG), a green tea polyphenolic catechin, has been known to possess a variety of beneficial biological activities. The in-vitro anti-cancer activity of EGCG is well documented. However, the use of EGCG in modern therapeutics is limited due to its poor bioavailability and limited stability at physiological pH. In this study, we have investigated the stability profiles of EGCG in aqueous solutions using UV-vis spectroscopy. Stability results showed very low stability profile of EGCG at physiological pH with rapid degradation under alkaline conditions. Therefore, we have encapsulated EGCG in solid lipid nanoparticles to increase its stability and evaluated for anticancer activity. The lipid core of nanoparticles not only provides an additional structural reinforcement to the nanoparticle assembly, but also makes it biologically compatible, thereby enabling a stealth vehicle for efficient drug delivery. EGCG loaded nanoparticles (EGCG-SLN) were characterized using dynamic light scattering, Fourier transform infrared spectroscopy and differential scanning calorimetry. EGCG and EGCG-SLN were evaluated for their anticancer activities by cellular proliferation. The cytotoxicity of EGCG-SLN was found to be 8.1 times higher against MDA-MB 231 human breast cancer cells and 3.8 times higher against DU-145 human prostate cancer cells than that of the pure EGCG.

Fabrication, characterization and bioevaluation of silibinin loaded chitosan nanoparticles.

Silibinin is reported to possess multiple biological activities. However, its hydrophobic nature limits its bioavailability compromising in vivo biological activities. Nanoparticles-based delivery of such molecules has emerged as new technique to resolve these issues. Bio-degradable, compatible and adhesive nature of chitosan has recently attracted its suitability as a carrier for biologically active molecules. This study presents fabrication and characterization of chitosan-tripolyphosphate based encapsulation of silibinin. Various preparations of silibinin encapsulated chitosan-tripolyphosphate nanoparticles were studied for particle size, morphology, zeta-potential, and encapsulation efficiencies. Preparations were also evaluated for cytotoxic activities in vitro. The optimized silibinin loaded chitosan nanoparticles were of 263.7±4.1nm in particle size with zeta potential 37.4±1.57mV. Nanoparticles showed high silibinin encapsulation efficiencies (82.94±1.82%). No chemical interactions between silibinin and chitosan were observed in FTIR analysis. Powder X-ray diffraction analysis revealed transformed physical state of silibinin after encapsulation. Surface morphology and thermal behaviour were determined using TEM and DSC analysis. Encapsulated silibinin displayed increased dissolution and better cytotoxicity against human prostate cancer cells (DU145) than silibinin alone.