Vaibhav Dubey

Development, characterization, and toxicity evaluation of amphotericin B–loaded gelatin nanoparticles

Our aim in the present investigation was to develop a nanoparticulate carrier of amphotericin B (AmB) for controlled delivery as well as reduced toxicity. Nanoparticles of different gelatins (GNPs) (type A or B) were prepared by two-step desolvation method and optimized for temperature, pH, amount of cross-linker, and theoretical drug loading. AmB-loaded GNPs were characterized for size, polydispersity index (PI), shape, morphology, surface charge, drug release, and hemolysis. The developed GNPs (GNP(A300)) were found to be of nanometric size (213 +/- 10 nm), having low PI (0.092 +/- 0.015) and good entrapment efficiency (49.0 +/- 2.9%). All GNPs showed biphasic release characterized by an initial burst followed by controlled release. The in vivo hematological toxicity results suggest nonsignificant reduction (P > .05) in hemoglobin concentration and hematocrit. Nephrotoxicity results showed that there was a nonsignificant (P > .05) increase in blood urea nitrogen and serum creatinine levels. The results confirm that developed GNPs could optimize AmB delivery in terms of cost and safety, and type A gelatin with bloom number 300 was found suitable for such preparation.

Systemic and mucosal immune response induced by transcutaneous immunization using Hepatitis B surface antigen-loaded modified liposomes

We have evaluated the efficiency of novel modified liposomes (ethosomes) for transcutaneous immunization (TCI) against Hepatitis B. Antigen-loaded ethosomes were prepared and characterized for shape, lamellarity, fluidity, size distribution, and entrapment efficiency. Spectral bio-imaging and flow cytometric studies showed efficient uptake of Hepatitis B surface antigen (HBsAg)-loaded ethosomes by murine dendritic cells (DCs) in vitro, reaching a peak by 180 min. Transcutaneous delivery potential of the antigen-loaded system using human cadaver skin demonstrated a much higher skin permeation of the antigen in comparison to conventional liposomes and soluble antigen preparation. Topically applied HBsAg-loaded ethosomes in experimental mice showed a robust systemic and mucosal humoral immune response compared to intramuscularly administered alum-adsorbed HBsAg suspension, topically applied plain HBsAg solution and hydroethanolic (25%) HBsAg solution. The ability of the antigen-pulsed DCs to stimulate autologous peripheral blood lymphocytes was demonstrated by BrdU assay and a predominantly TH1 type of immune response was observed by multiplex cytometric bead array analysis. HBsAg-loaded ethosomes are able to generate a protective immune response and their ability to traverse and target the immunological milieu of the skin may find a potential application in the development of a transcutaneous vaccine against Hepatitis B virus (HBV).

Enhanced transdermal delivery of an anti-HIV agent via ethanolic liposomes.

Indinavir, as a protease inhibitor with a short biological half life, variable pH-dependent oral absorption, and extensive first-pass metabolism, presents a challenge with respect to its oral administration. The current work aims to formulate and characterize indinavir-bearing ethanolic liposomes (ethosomes), and to investigate their enhanced transdermal delivery potential. The prepared ethanolic liposomes were characterized to be spherical, unilamellar structures having low polydispersity, nanometric size range, and improved entrapment efficiency over other delivery formulations. Permeation studies of indinavir across human cadaver skin resulted in enhanced transdermal flux from ethanolic liposomes that was significantly (P < 0.05) greater than that with ethanolic drug solution, conventional liposomes, or plain drug solution. Additionally, the ethanolic liposomes showed the shortest lag time for indinavir, thus presenting a suitable approach for transdermal delivery of this protease inhibitor. From the clinical editor: This study characterizes indinavir bearing ethanolic liposomes (ethosomes), and investigate their enhanced transdermal delivery potential, demonstrating a potentially a suitable approach for transdermal delivery of this protease inhibitor for HIV treatment, which typically has been associated with limited bioavailability via the oral route.

Carbon nanotubes and their toxicity

The vital need of studying the toxicological profile of carbon nanotubes (CNTs) has emerged from the rapidly enhancing utility of CNTs in the field of nanobiology and drug delivery. This review highlights the vivid aspect of CNTs’ toxicity comprising of in-vitro to in-vivo toxicological profile vis-à-vis the various potential routes of CNTs exposure. The article also underlines the various surface modifications on carbon nanotubes and its role in imparting biocompatibility to the CNTs, further suggesting their utility as a safer delivery module for bioactives.

Carbohydrate-conjugated multiwalled carbon nanotubes: development and characterization

UNLABELLED This work presents a novel cascade of chemical functionalization of multiwalled carbon nanotubes (MWCNTs) through chemical modification by a carbohydrate, D-galactose. Galactose-conjugated or galactosylated MWCNTs were synthesized involving the sequential steps of carboxylation, acylation, amine modification, and finally, galactose conjugation. The modification of MWCNTs with galactose was investigated by elemental analysis, x-ray diffraction analysis, Fourier transform-infrared spectroscopy, Raman spectroscopy, and zeta potential measurements, at every sequential step of functionalization. Size and surface characteristics of chemically modified MWCNTs were monitored by transmission electron microscopy and scanning electron microscopy. That galactosylation improved the dispersibility of MWCNTs in aqueous solvents was confirmed by investigation of their dispersion characteristics at different pH values. Thus, the galactosylated MWCNTs as developed could be used for delivery of different bioactive(s) as well as active ligand (galactose)-based targeting to hepatic tissue. FROM THE CLINICAL EDITOR This work presents a novel cascade of functionalization of multiwalled carbon nanotubes (MWCNTs) through chemical modification by a carbohydrate. Galactosylation improves the dispersibility of MWCNTs in aqueous solvents. The galactosylated MWCNTs could be used for delivery of different bioactive(s) as well as active ligand-based targeting to hepatic tissue.

In vitro evaluation of surface functionalized gelatin nanoparticles for macrophage targeting in the therapy of visceral leishmaniasis.

The present study evaluates the potential of surface functionalized gelatin nanoparticles (f-GNPs) for efficient macrophage-specific delivery of amphotericin B (AmB) in the treatment of visceral leishmaniasis (VL). Further, the effect of spacer for macrophage targeting was also evaluated. Gelatin was functionalized either through conjugation to mannose via direct coupling (mGelatin) or via PEG spacer (m-Gelatin), and the synthesis was confirmed by FTIR. AmB-loaded f-GNPs, that is, mGNPs and m-GNPs prepared from mGelatin and m-Gelatin conjugates, respectively, were characterized. In vitro concanavalin A (Con-A) agglutination assay confirmed the availability of mannose on the surface of these f-GNPs. Kinetics of cellular uptake of AmB-loaded f-GNPs by J774A.1 macrophage cells assessed through flow cytometry demonstrated a steady increase and maximum cell-associated fluorescence was observed at 4h for m-GNPs and 6 h for m-GNPs. Measurement of cytotoxicity using Annexin-V–FITC/PI apoptosis assay delineated marginal changes (7–9%) in treated macrophages following 48 h incubation, establishing the safety of f-GNPs. m-GNPs showed a 5.4-fold reduction in IC50 in comparison with plain AmB suggesting significant enhancement of antileishmanial activity. Our results indicate that f-GNPs could be a promising carrier for specific delivery of AmB to macrophages for effective treatment of VL. Furthermore, spacer contributed significantly in reducing the cytotoxicity as well as increasing the uptake and activity of f-GNPs.

Evaluation of Solid Lipid Nanoparticles as Carriers for Delivery of Hepatitis B Surface Antigen for Vaccination Using Subcutaneous Route

PURPOSE Solid lipid nanoparticles (SLN) have emerged as carriers for therapeutic peptides, proteins, antigens and bioactive molecules. We have explored the potential of SLN as carrier for Hepatitis B surface antigen (HBsAg) by surface modifications to enhance their loading efficiency and the cellular uptake, using subcutaneous route. METHODS Four different formulations of SLN were prepared by solvent injection method and characterized for various physical properties: particle size, surface morphology, shape, zeta potential, polydispersity, X-ray diffraction analysis, release profile and entrapment efficiency. HBsAg loaded SLN were studied for their functional characteristics, in vitro cellular uptake and internalization studies by human dendritic cells, macrophages and fibroblasts, T cell proliferation and TH1/TH2 response. Humoral immune response elicited by subcutaneously administered HBsAg containing SLN formulations were studied in vivo in mice. RESULTS Compared to soluble HBsAg; SLN, particularly the mannosylated formulation, showed better cellular uptake, lesser cytotoxicity and induction of greater TH1 type of immune response. They also showed better immunological potential by producing sustained antibody titer. CONCLUSION Mannosylated SLN appears to be promising as carrier for vaccine delivery against hepatitis B as ascertained by in vitro and in vivo studies, however further investigations on humans are required to establish their potential as vaccines against hepatitis B infection.

Comparative evaluation of hepatitis B surface antigen–loaded elastic liposomes and ethosomes for human dendritic cell uptake and immune response

UNLABELLED The aim of the present study was to evaluate two vesicular carrier systems, ethosomes and elastic liposomes loaded with hepatitis B surface antigen, for in vitro qualitative and quantitative uptake by human dendritic cells (DCs) and ability to stimulate T lymphocytes. Quantitative uptake of antigen-loaded carriers was documented by flow cytometry, and internalization of the systems by the DCs was studied using spectral bioimaging. Ability of antigen-pulsed DCs to stimulate autologous peripheral blood lymphocytes and levels of TH1/TH2 cytokines were also examined using flow cytometry. Both vesicular carrier systems as antigen delivery modules and DCs as antigen-presenting cells were able to generate a protective immune response. However, ethosomes were found to have higher internalizing ability and immunogenicity in comparison with elastic liposomes. These properties of ethosomes coupled with their skin-navigating potential, make it an attractive vehicle for development of a transcutaneous vaccine against hepatitis B in preference to elastic liposomes. FROM THE CLINICAL EDITOR Two carrier systems for more potent vaccine administration - ethosomes and elastic liposomes loaded with hepatitis B surface antigen - are compared. Ethosomes demonstrated higher internalizing ability and immunogenicity. Due to their known skin-navigating potential, ethosomes may represent an attractive vehicle for development of a transcutaneous vaccine against hepatitis B.

Vesicles as tools for the modulation of skin permeability

Human skin is a remarkably efficient barrier designed to keep our insides in and the outside out. The modulation of this efficient barriers properties, including its permeability to chemicals, drugs and biologically active agents is the prime target for various dermal, transdermal, drug, antigen and gene delivery approaches. Therefore, several methods have been attempted to enhance the permeation rate of biologically active agents, temporarily and locally. One of the approaches is the application of drug-laden vesicular formulations. This review presents various mechanisms involved in increasing drug transport across the skin via different vesicular approaches, such as liposomes, elastic vesicles and ethosomes, along with compiling the research work conducted in this field.

Elastic Liposomes Mediated Transdermal Delivery of An Anti-Jet Lag Agent:Preparation, Characterization and In Vitro Human Skin Transport Study

In order to get across the intact skin, drug-laden carriers have to pass through narrow, confining pores of 50 nm or less diameter, under the influence of a suitable transdermal gradient. Novel ultradeformable carriers, the elastic liposomes achieve this target via its deforming and self-optimizing property. The main goal of this work was to prepare and characterize, elastic liposomes bearing melatonin, an anti-jet lag agent for its efficient transdermal delivery. Elastic liposomes bearing melatonin were prepared by modified extrusion method and characterized for shape, lamellarity, size distribution, percent drug loading, turbidity profile by Transmission electron microscopy (TEM), Dynamic light scattering (DLS), Mini-column centrifugation and Nephelometric techniques. The effect of different formulation variables like type of surfactant and concentration of surfactant on the deformability of vesicles, turbidity changes, transdermal flux across human cadaver skin, amount of drug deposited into the skin were investigated. Confocal laser scanning (CLS) micrographs revealed that probe (Rhodamine Red) loaded elastic liposomes were able to penetrate much deeper than the probe loaded conventional rigid liposomes. Out of the three surfactants utilized namely, Span 80, Sodium cholate and Sodium dodecylsulphate, formulation bearing Span 80 at an optimum lipid: surfactant ratio of 85:15% w/w proved to be the best in all parameters studied. The optimum skin permeation profile including greater transdermal flux and lower lag time of melatonin from optimized elastic liposomes via human cadaver skin was observed. Our results of the present study demonstrated the feasibility of elastic liposomal system for transdermal delivery of this anti- jet lag agent, which provides better transdermal flux, higher entrapment efficiency, greater skin drug deposition and possesses the ability of a self-penetration enhancer as compared to conventional liposomes.