Cobalt doped nano-hydroxyapatite incorporated gum tragacanth-alginate beads as angiogenic-osteogenic cell encapsulation system for mesenchymal stem cell based bone tissue engineering.

Angiogenic-osteogenic cell encapsulation system is a technical need for human mesenchymal stem cell (hMSC)-based bone tissue engineering (BTE). Here, we have developed a highly efficient hMSC encapsulation system by incorporating bivalent cobalt doped nano-hydroxyapatite (HAN) and gum tragacanth (GT) as angiogenic-osteogenic components into the calcium alginate (CA) beads. Physico-chemical characterizations revealed that the swelling and degradation of HAN incorporated CA-GT beads (GT-HAN) were 1.34 folds and 2 folds higher than calcium alginate (CA) beads. Furthermore, the diffusion coefficient of solute molecule was found 2.5-fold higher in GT-HAN with respect to CA bead. It is observed that GT-HAN supports the long-term viability of encapsulated hMSC and causes 50% less production of reactive oxygen species (ROS) in comparison to CA beads. The expression of osteogenic differentiation markers was found 1.5-2.5 folds higher in the case of GT-HAN in comparison to CA. A similar trend was observed for hypoxia inducible factor 1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF). The soluble secretome from hMSC encapsulated in the GT-HAN induced proliferation of endothelial cells and supported tube formation (2.5-fold higher than CA beads). These results corroborated that GT-HAN could be used as an angiogenic-osteogenic cell encapsulation matrix for hMSC encapsulation and BTE application.

Silanization improves biocompatibility of graphene oxide.

Evaluation of the biological properties of silanized graphene oxide is important in the context of biomedical applications of the material. In this study, we have evaluated the toxicity, immunogenicity and other biological properties like osteogenicity of silanized graphene oxide (SiGO). Graphene oxide (GO) was silanized using a common silanizing agent namely (3-aminopropyl) triethoxysilane (APTES). Silanization was confirmed through infrared spectroscopy and elemental mapping. Post-silanization, we did not observe any significant changes in the morphology of GO. Silanization leads to an increase in the interlayer distance and disorder in the lattice. Study of in vitro toxicity of SiGO on three different cell lines namely primary human dermal fibroblast, murine embryonic fibroblast and human osteosarcoma cell lines revealed that toxicity of SiGO was significantly less than GO. We further showed that in vitro immune activation of macrophage was less in the case of SiGO in comparison to GO. Profiling of osteogenic differentiation of human mesenchymal stem cell revealed that SiGO is less osteogenic than GO. Study of acute toxicity in the murine model indicated that GO was hepatotoxic at experimental concentration whereas SiGO did not show any significant toxicity. This study implied that SiGO is a better biocompatible material than GO.

Anionic Dinuclear Oxidovanadium(IV) Complexes with Azo Functionalized Tridentate Ligands and µ-Ethoxido Bridge Leading to an Unsymmetric Twisted Arrangement: Synthesis, X-ray Structure, Magnetic Properties, and Cytotoxicity.

The synthesis of ethoxido-bridged dinuclear oxidovanadium(IV) complexes of the general formula (HNEt3)[(VOL1-3)2(µ-OEt)] (1-3) with the azo dyes 2-(2'-carboxy-5'-X-phenylazo)-4-methylphenol (H2L1, X = H; H2L2, X = NO2) and 2-(2'-carboxy-5'-Br-phenylazo)-2-naphthol (H2L3) as ligands is reported. The ligands differ in the substituents at the phenyl ring to probe their influence on the redox behavior, biological activity, and magnetochemistry of the complexes, for which the results are presented and discussed. All synthesized ligands and vanadium(IV) complexes have been characterized by various physicochemical techniques, namely, elemental analysis, electrospray ionization mass spectrometry, spectroscopic methods (UV/vis and IR), and cyclic voltammetry. X-ray crystallography of 1 and 3 revealed the presence of a twisted arrangement of the edged-shared bridging core unit. In agreement with the distorted nature of the twisted core, antiferromagnetic exchange interactions were observed between the vanadium(IV) centers of the dinuclear complexes with a superexchange mechanism operative. These results have been verified by DFT calculations. The complexes were also screened for their in vitro cytotoxicity against HeLa and HT-29 cancer cell lines. The results indicated that all the synthesized vanadium(IV) complexes (1-3) were cytotoxic in nature and were specific to a particular cell type. Complex 1 was found to be the most potent against HeLa cells (IC50 value 1.92 µM).

Photo-triggered destabilization of nanoscopic vehicles by dihydroindolizine for enhanced anticancer drug delivery in cervical carcinoma.

The efficacy and toxicity of drugs depend not only on their potency but also on their ability to reach the target sites in preference to non-target sites. In this regards destabilization of delivery vehicles induced by light can be an effective strategy for enhancing drug delivery with spatial and temporal control. Herein we demonstrate that the photoinduced isomerization from closed (hydrophobic) to open isomeric form (hydrophilic) of a novel DHI encapsulated in liposome leads to potential light-controlled drug delivery vehicles. We have used steady state and picosecond resolved dynamics of a drug 8-anilino-1-naphthalenesulfonic acid ammonium salt (ANS) incorporated in liposome to monitor the efficacy of destabilization of liposome in absence and presence UVA irradiation. Steady state and picosecond resolved polarization gated spectroscopy including the well-known strategy of solvation dynamics and Förster resonance energy transfer; reveal the possible mechanism out of various phenomena involved in destabilization of liposome. We have also investigated the therapeutic efficacy of doxorubicin (DOX) delivery from liposome to cervical cancer cell line HeLa. The FACS, confocal fluorescence microscopic and MTT assay studies reveal an enhanced cellular uptake of DOX leading to significant reduction in cell viability (∼40%) of HeLa followed by photoresponsive destabilization of liposome. Our studies successfully demonstrate that these DHI encapsulated liposomes have potential application as a smart photosensitive drug delivery system.

Magnetic nanoparticle incorporated oleogel as iontophoretic drug delivery system.

In this article, we validated the use of electric current as an external stimulus to induce an enhancement of drug release from magnetic nanoparticle (MNP) incorporated organogels (magnetogel) under iontophoretic conditions. For this purpose, we adopted a simple, two-step synthesis route to incorporate magnetic (Fe3O4) nanoparticles (MNP) and ciprofloxacin hydrochloride within the network of a soybean oil-based oleogel using stearic acid as gelator. We fabricated a series of MNP incorporated oleogels by varying the wt% of MNPs while keeping a constant weight ratio of soybean oil:stearic acid. The microstructures of the magnetogels were analyzed in MNP concentration-dependent manner by optical microscopy, powder X-ray diffraction, FTIR, mechanical, and electrical studies. Detailed analysis of the electrical properties revealed that the gel sample with a maximum proportion of MNP (S4) allowed the maximum passage of current through it among all the compositions. Under the iontophoretic environment of the active condition, we observed nearly 2.5 fold increase in cumulative drug release in case of sample S4 compared to the corresponding passive condition. These observations suggested that in future, our magnetogel formulation can be further developed as AC field induced 'remote controlled' agent for therapeutic application.

Mesoporous silica nanoparticle based enzyme responsive system for colon specific drug delivery through guar gum capping.

In the global context of increasing colonic diseases, colon specific oral drug delivery systems have shown promise as an effective therapeutic modality. Herein, we developed a mesoporous silica nanoparticle (MSN) based enzyme responsive materials for colon specific drug delivery. We have utilized guar gum, a natural carbohydrate polymer as a capping layer to contain a model drug, such as 5-flurouracil (5FU) within the mesoporous channels of MSN. Analytical characterization including electron microscopy, PXRD, nitrogen sorption, thermogravimetric analysis and FTIR, confirmed that the synthesized MSN with size less than 100nm is of MCM-41type. The studies further showed that the MSN maintained their discrete nanoparticle identity after guar gum capping through non-covalent interaction. The release of 5FU from guar gum capped MSN (GG-MSN) was specifically triggered via enzymatic biodegradation of guar gum by colonic enzymes in the simulated colonic microenvironment. Subsequently, the released drug manifested anticancer activity in colon cancer cell lines in vitro confirmed by flow cytometry and biochemical assay. The drug loaded GG-MSN system also demonstrated near perfect 'zero release' property in absence of enzymes in different simulated conditions of the gastrointestinal tract. Our study provides an important intermediate step to apply such GG-MSN based engineered nanomaterials for further detailed in vivo investigation.

Alginate Bead Based Hexagonal Close Packed 3D Implant for Bone Tissue Engineering.

Success of bone tissue engineering (BTE) relies on the osteogenic microarchitecture of the biopolymeric scaffold and appropriate spatiotemporal distribution of therapeutic molecules (growth factors and drugs) inside it. However, the existing technologies have failed to address both the issues together. Keeping this perspective in mind, we have developed a novel three-dimensional (3D) implant prototype by stacking hexagonal close packed (HCP) layers of calcium alginate beads. The HCP arrangement of the beads lead to a patterned array of interconnected tetrahedral and octahedral pores of average diameter of 142.9 and 262.9 µm, respectively, inside the implant. The swelling pattern of the implants changed from isotropic to anisotropic in the z-direction in the absence of bivalent calcium ions (Ca2+) in the swelling buffer. Incubation of the implant in simulated body fluid (SBF) resulted in a 2.7-fold increase in the compressive modulus. The variation in the relaxation times as derived from the Weichert viscoelasticity model predicted a gradual increase in the interactions among the alginate molecules in the matrix. We demonstrated the tunability of the spatiotemporal drug release from the implant in a tissue mimicking porous semisolid matrix as well as in conventional drug release set up by changing the spatial coordinates of the "drug loaded depot layer" inside the implant. The therapeutic potential of the implant was confirmed against Escherichia coli using metronidazole as the model drug. Detailed analysis of cell viability, cell cycle progression, and cytoskeletal reorganization using osteoblast cells (MG-63) proved the osteoconductive nature of the implant. Expression of differentiation markers such as alkaline phosphatase, runx2, and collagen type 1 in human mesenchymal stem cell in vitro confirmed the osteogenic nature of the implant. When tested in vivo, VEGF loaded implant was found capable of inducing angiogenesis in a mice model. In conclusion, the bead based implant may find its utility in non-load-bearing BTE.

Cobalt doped proangiogenic hydroxyapatite for bone tissue engineering application.

The present study delineates the synthesis and characterization of cobalt doped proangiogenic-osteogenic hydroxyapatite. Hydroxyapatite samples, doped with varying concentrations of bivalent cobalt (Co(2+)) were prepared by the ammoniacal precipitation method and the extent of doping was measured by ICP-OES. The crystalline structure of the doped hydroxyapatite samples was confirmed by XRD and FTIR studies. Analysis pertaining to the effect of doped hydroxyapatite on cell cycle progression and proliferation of MG-63 cells revealed that the doping of cobalt supported the cell viability and proliferation up to a threshold limit. Furthermore, such level of doping also induced differentiation of the bone cells, which was evident from the higher expression of differentiation markers (Runx2 and Osterix) and better nodule formation (SEM study). Western blot analysis in conjugation with ELISA study confirmed that the doped HAp samples significantly increased the expression of HIF-1α and VEGF in MG-63 cells. The analysis described here confirms the proangiogenic-osteogenic properties of the cobalt doped hydroxyapatite and indicates its potential application in bone tissue engineering.