Prajakta Dandekar

Diagnostic nanocarriers for sentinel lymph node imaging.

In the last decade, methods for the precise localization of sentinel lymph node (SLN) have drawn tremendous attention by cancer surgeons and researchers in the field of medical diagnosis. The accurate identification and characterization of lymph nodes by imaging has important therapeutic and prognostic significance in patients with newly diagnosed cancers. The SLN is the first lymph node that receives lymphatic drainage from the site of a primary tumor. The sentinel node is much more likely to contain metastatic tumor cells than other lymph nodes in the same region. Amongst the various exploited methods for SLN diagnosis, nanocarriers have received increasing attention as lymph node delivery agents. The present review focuses on various such particulate carriers namely radiolabeled sulfur colloids, liposomes, quantum dots, dendrimers and magnetic nanoparticles, which are most extensively studied and have been attributed with the most desirable characteristics for SLN imaging.

Curcumin-Loaded Hydrogel Nanoparticles: Application in Anti-Malarial Therapy and Toxicological Evaluation

The present investigation involved preparation of hydrogel nanoparticles using a combination of hydroxyl propyl methyl cellulose and polyvinyl pyrrolidone. The objective was to exploit the size and hydrophilic nature of the formulated nanocarriers to enhance absorption and prolong the rapid clearance of curcumin due to possible evasion of the reticulo-endothelial system. Reproducible nanoparticles of size around 100 nm, a fairly narrow distribution and encapsulation efficiency of 72%, were produced by the solvent emulsion-evaporation technique. This optimized system was further subjected to freeze-drying. The freeze-dried product was readily reconstituted with distilled water. The reconstituted product exhibited a size and distribution similar to that before freeze-drying, drug content of greater than 99% and presence of amorphous drug when analyzed by differential scanning calorimetry (DSC) which may result in possible improved absorption of curcumin. In vivo anti-malarial studies revealed significant superior action of nanoparticles over curcumin control suggesting the possibility of the formulation being employed as an adjunct anti-malarial therapy along with the standard therapy. Acute and subacute toxicity studies confirmed the oral safety of the formulation. A battery of genotoxicity studies was conducted to evaluate the nongenotoxic potential of the developed formulation thus indicating the possibility of the formulation being employed for prolonged duration.

Toxicological evaluation of pH-sensitive nanoparticles of curcumin: Acute, sub-acute and genotoxicity studies

Research in nanotoxicology is still in nascent stages. This hampers the design of appropriate regulatory policies for these beneficial nano-drug delivery systems thus affecting their routine employment as therapeutics. Establishing the entire toxicological profile is thus indispensable for proving the human safety of nanocarriers, which was the primary objective of the current investigation. The developed curcumin loaded polymeric nanoparticles of Eudragit S100 were subjected to various toxicological evaluations which included acute-toxicity study, sub-acute-toxicity study (28 days) and various genotoxicity studies like in vivo Micronucleus assay, in vivo Chromosomal Aberration assay and in vivo Comet assay. The formulation was found to be non-toxic at the dose equivalent to 2000 mg/kg of body weight of curcumin in the acute-toxicity study. Sub-acute-toxicity study proved the safety of the formulation for prolonged administration at the commonly used therapeutic dose of 100mg/kg of body weight of curcumin and at twice the therapeutic dose. Genotoxicity studies proved the cellular safety of the developed formulation at the therapeutic dose, and even at doses equivalent to thrice the therapeutic dose. Thus the developed curcumin loaded polymeric nanoparticles of Eudragit S100 were found to be safe for oral administration for a short as well as a prolonged duration.

A Hydrophobic Starch Polymer for Nanoparticle‐Mediated Delivery of Docetaxel

A hydrophobic starch derivative is used for safe and enhanced delivery of anticancer agents. The synthesis and characterization of propyl starch with a controlled degree of substitution to modulate the release of the encapsulated hydrophobic drug is reported. The application of this polymer for formulating nanoparticles of docetaxel, an anti-cancer agent effective against numerous types of cancers but possessing intrinsic formulation difficulties is described. The solvent emulsification/diffusion technique is used and the synthesis is optimized with respect to several formulation parameters. Uptake studies with these nanoparticles indicate their enhanced internalization by the cancerous cells and their peri-nuclear localization.

Cellular delivery of polynucleotides by cationic cyclodextrin polyrotaxanes

Cationic polyrotaxanes, obtained by temperature activated threading of cationic cyclodextrin derivatives onto water-soluble cationic polymers (ionenes), form metastable nanometric polyplexes with pDNA and combinations of siRNA with pDNA. Because of their low toxicity, the polyrotaxane polyplexes constitute a very interesting system for the transfection of polynucleotides into mammalian cells. The complexation of Cy3-labeled siRNA within the polyplexes was demonstrated by fluorescence correlation spectroscopy. The uptake of the polyplexes (red) was imaged by confocal fluorescence microscopy using the A549 cell line as a model (blue: nuclei, green: membranes). The results prove the potential of polyrotaxanes for further investigations involving knocking down genes of therapeutic interest.

Formulation and evaluation of novel micellar nanocarrier for nasal delivery of sumatriptan

AIM The investigation was aimed at designing a micellar nanocarrier of sumatriptan for nose-to-brain delivery and to identify the probable pathway of drug transport to the brain. MATERIALS & METHODS Micellar nanocarriers were formulated using various safe and acceptable excipients. Optimized formulation was characterized for particle size by multiangle dynamic light scattering, small-angle neutron scattering and cryo-transmission electron microscopy. (99m)Tc was used as a radiolabeling agent to radiolabel sumatriptan for in vivo studies. RESULTS Various characterization studies demonstrated the nanometric, homogenous and spherical nature of the developed micellar nanocarrier. Biodistribution and autoradiography studies in rats showed a significantly higher brain uptake of sumatriptan micellar nanocarrier as compared with sumatriptan solution. CONCLUSION Preliminary investigations in rats indicated the potential of the developed micellar nanocarrier for nose-to-brain delivery of sumatriptan. These investigations in lower animals provided an excellent lead to further evaluate the formulation in higher animals and finally in clinical settings.

pH-sensitive nanoparticles of curcumin-celecoxib combination: evaluating drug synergy in ulcerative colitis model.

Inflammatory bowel diseases, which largely comprise ulcerative colitis (UC) and Crohns disease, are increasingly posing as a global threat because of the incompetence of the current therapy in the entire patient population. This necessitates the identification of alternative therapeutic molecules or their combinations, which may serve as effective first-line or maintenance therapeutics. In this quest, celecoxib, a selective cyclooxygenase-2 inhibiting nonsteroidal anti-inflammatory agent and curcumin, a natural antioxidant and anti-inflammatory agent, have both been found to be useful in alleviating UC. Furthermore, studies involving their combination have proved synergistic action of these two agents. In the current investigation, we have formulated pH-sensitive nanoparticles of curcumin-celecoxib combination as a potential therapy for UC. Synergistic action of the drug combination, delivery advantages of nanosized carriers, and pH-sensitive nature of the polymer were collectively hypothesized to reduce the overall toxicity and total dose of celecoxib and provide enhanced efficacy for mitigating UC. The hypothesis was confirmed in a UC model in rats, where pH-sensitive nanoparticles of the drug combination were found to be more efficacious than nanoparticles of either drugs or drug/s suspension. Further, the blank nanoparticles did not exhibit any therapeutic effect, thereby confirming efficacy of the drug combination for treating UC.

Improved mucoadhesion and cell uptake of chitosan and chitosan oligosaccharide surface-modified polymer nanoparticles for mucosal delivery of proteins.

The main aim of the present study was to compare mucoadhesion and cellular uptake efficiency of chitosan (CS) and chitosan oligosaccharide (COS) surface-modified polymer nanoparticles (NPs) for mucosal delivery of proteins. We have developed poly (d, l-lactide-co-glycolide) (PLGA) NPs, surface-modified COS-PLGA NPs and CS-PLGA NPs, by using double emulsion solvent evaporation method, for encapsulating bovine serum albumin (BSA) as a model protein. Surface modification of NPs was confirmed using physicochemical characterization methods such as particle size and zeta potential, SEM, TEM and FTIR analysis. Both surface-modified PLGA NPs displayed a slow release of protein compared to PLGA NPs. Furthermore, we have explored the mucoadhesive property of COS as a material for modifying the surface of polymeric NPs. During in vitro mucoadhesion test, positively charged COS-PLGA NPs and CS-PLGA NPs exhibited enhanced mucoadhesion, compared to negatively charged PLGA NPs. This interaction was anticipated to improve the cell interaction and uptake of NPs, which is an important requirement for mucosal delivery of proteins. All nanoformulations were found to be safe for cellular delivery when evaluated in A549 cells. Moreover, intracellular uptake behaviour of FITC-BSA loaded NPs was extensively investigated by confocal laser scanning microscopy and flow cytometry. As we hypothesized, positively charged COS-PLGA NPs and CS-PLGA NPs displayed enhanced intracellular uptake compared to negatively charged PLGA NPs. Our results demonstrated that CS- and COS-modified polymer NPs could be promising carriers for proteins, drugs and nucleic acids via nasal, oral, buccal, ocular and vaginal mucosal routes.

Enhanced cellular delivery of idarubicin by surface modification of propyl starch nanoparticles employing pteroic acid conjugated polyvinyl alcohol

Enhanced intracellular internalization of the anti-cancer active idarubicin (IDA) was achieved through appropriate surface modification of IDA loaded propyl starch nanoparticles. This was conducted by synthesizing pteroic acid modified polyvinyl alcohol (ptPVA) and employing this stabilizer for formulating the said nanoparticles. Pteroic acid attached at the nanoparticles improved the surface protein adsorption of the nanoparticle, a condition which the nanoparticles would largely experience in vitro and in vivo and hence improve their cellular internalization. Spherical, homogenous IDA nanoparticles (214 ± 5 nm) with surface modified by ptPVA were formulated using the solvent emulsification-diffusion technique. The encapsulation efficiency and drug loading amounted around 85%. In vitro release studies indicated a controlled release of IDA. Safety and efficacy of the nanoparticles was confirmed by suitable cellular cytotoxicity assays. Protein binding studies indicated a higher adsorption of the model protein on nanoparticles formulated with ptPVA as compared to PVA. Cellular uptake studies by confocal laser scanning microscopy revealed a higher cellular uptake of ptPVA stabilized nanoparticles thus confirming the proposed hypothesis of higher protein adsorption being responsible for higher cellular internalization.

Freeze Drying: Potential for Powdered Nanoparticulate Product

Nanoparticles were prepared by using an emulsion solvent evaporation method. Further, the drying of an anti-cancer drug of proprietary nature (nanosized) was carried out by a freeze-drying technique to get a free-flowing powder. A systematic approach was developed to study the freeze-drying technique for polymeric nanoparticles. Initially, the freeze-thawing experiments were carried out with varying concentrations of cryoprotectants to screen the most suitable cryoprotectant. Subsequently, the freeze drying was carried out with the selected cryoprotectants to study their effect on the final product quality after drying. Annealing experiments were carried out to optimize the freeze-drying cycle time and study its effect on the particle size of nanoparticles. The effect of selected cryoprotectant on the heat and mass transfer parameters was also studied. Finally, the simulation of the freezing temperature was carried out by using MATLAB 7.0 software. The lyophilized product was characterized in terms of appearance and particle size by photon correlation spectroscopy (PCS) and X-ray powder diffraction (XRD). The lyophilized product obtained with mannitol (0.2% w/v) and lactose (0.5% w/v) as cryoprotectant resulted into a slight increase in particle size after freeze drying.