Mesoporous silica-chondroitin sulphate hybrid nanoparticles for targeted and bio-responsive drug delivery

This work proposes the fabrication of a novel targeted drug delivery system based on mesoporous silica-biopolymer hybrids that can release drugs in response to biological stimuli present in cancer cells. The proposed system utilizes mesoporous silica nanoparticles as a carrier to host the drug molecules. A bio-polymer cap is attached onto these particles which serves the multiple functions of drug retention, targeting and bio-responsive drug release. The biopolymer chondroitin sulphate used here is a glycosaminoglycan that can specifically bind to receptors over-expressed in cancer cells. This molecule also possesses the property of disintegrating upon exposure to enzymes over-expressed in cancer cells. When these particles interact with cancer cells, the chondroitin sulphate present on the surface recognizes and attaches onto the CD44 receptors facilitating the uptake of these particles. The phagocytised particles are then exposed to the degradative enzymes, such as hyaluronidase present inside the cancer cells, which degrade the cap resulting in drug release. By utilizing a cervical cancer cell line we have demonstrated the targetability and intracellular delivery of hydrophobic drugs encapsulated in these particles. It was observed that the system was capable of enhancing the anticancer activity of the hydrophobic drug curcumin. Overall, we believe that this system might prove to be a valuable candidate for targeted and bioresponsive drug delivery.

Bio-inspired route for the synthesis of spherical shaped MgO:Fe3+ nanoparticles: Structural, photoluminescence and photocatalytic investigation

MgO:Fe3+ (0.1-5 mol%) nanoparticles (NPs) were synthesized via eco-friendly, inexpensive and simple low temperature solution combustion route using Aloe vera gel as fuel. The final products were characterized by SEM, TEM and HRTEM. PXRD data and Rietveld analysis revealed the formation of cubic system. The influence of Fe3+ ion concentration on the structure morphology, UV absorption, PL emission and photocatalytic activity of MgO:Fe3+ NPs were investigated. The yellow emission with CIE chromaticity coordinates (0.44, 0.52) and average correlated color temperature value was found to be 3540 K which corresponds to warm light of NPs. The control of Fe3+. on MgO matrix influences the photocatalytic decolorization of methylene blue (MB) under UV light. The enhanced photocatalytic activity of MgO:Fe3+ (4 mol%) was attributed to dopant concentration, effective crystallite size, textural properties, decreased band gap and capability for reducing the electron hole pair recombination. Further, the trends of inhibitory effect in the presence of different radical scavengers were explored. These findings open up new avenues for the exploration of Fe-doped MgO in eco-friendly water applications and in the process of display devices. (C) 2015 Elsevier B.V. All rights reserved.

Dispersible crystalline nanobundles of YPO4 and Ln (Eu, Tb)-doped YPO4: rapid synthesis, optical properties and bio-probe applications

Undoped and Ln(3+) (Eu and Tb)-doped crystalline nanobundles of YPO4 were prepared by a facile microwave-assisted route with water as a solvent and without using any surfactant. TEM investigations reveal that the as-prepared powder consists of lenticular-shaped nanobundles (similar to 100 nm in diameter) made of very small nanorods with diameter less than 10 nm and length varying from 20 to 50 nm. Each nanorod in turn is single crystalline, as revealed by HRTEM imaging. The as-prepared nanobundles are easily dispersible in various solvents, especially water, without any surface functionalization, which is critical for various bio-probe applications like cell and tissue imaging. The Eu- and Tb-doped YPO4 nanobundles show good photoluminescence properties and were further evaluated for their use as fluorescent biolabels. Our results show that HeLa cells labelled with Eu- and Tb-doped YPO4 nanobundles show bright red (Eu) and green (Tb) intracellular luminescence under a confocal microscope. Concentration-and time-dependent MTT cell viability assays show that the nanobundles show low toxicity towards cells which makes them promising in bioimaging field.

Fusing the Navigation Information of Dual Foot-Mounted Zero-Velocity-Update-Aided Inertial Navigation Systems

A range constraint method viz. centroid method is proposed to fuse the navigation information of dual (right and left) foot-mounted Zero-velocity-UPdaTe (ZUPT)-aided Inertial Navigation Systems (INSs). Here, the range constraint means that the distance of separation between the position estimates of right and left foot ZUPT-aided INSs cannot be greater than a quantity known as foot-to-foot maximum separation. We present the experimental results which illustrate the applicability of the proposed method. The results show that the proposed method significantly enhances the accuracy of the navigation solution when compared to using two uncoupled foot-mounted ZUPT-aided INSs. Also, we compare the performance of the proposed method with the existing data fusion methods.

The Holy Grail of Polymer Therapeutics for Cancer Therapy: An Overview on the Pharmacokinetics and Bio Distribution

In recent years, multifaceted clinical benefits of polymeric therapeutics have been reported. Over the past decades, cancer has been one of the leading causes of mortality in the world. Many clinically approved chemotherapeutics encounter potential challenges against deadly cancer. Moreover, safety and efficacy of anticancer agents have been limited by undesirable pharmacokinetics and biodistribution. To address these limitations, various polymer drug conjugates are being studied and developed to improve the antitumor efficacy. Among other therapeutics, polymer therapeutics are well established platforms that circumvent anticancer therapeutics from enzymatic metabolism via direct conjugation to therapeutic molecules. Interestingly, polymer therapeutics meets an unmet need of small molecules. Further clinical study showed that polymer-drug conjugation can achieve desired pharmacokinetics and biodistribution properties of several anticancer drugs. The present retrospective review mainly enlightens the most recent preclinical and clinical studies include safety, stability, pharmacokinetic behavior and distribution of polymer therapeutics.

l(1)-K-SVD: A robust dictionary learning algorithm with simultaneous update

We develop a new dictionary learning algorithm called the l(1)-K-svp, by minimizing the l(1) distortion on the data term. The proposed formulation corresponds to maximum a posteriori estimation assuming a Laplacian prior on the coefficient matrix and additive noise, and is, in general, robust to non-Gaussian noise. The l(1) distortion is minimized by employing the iteratively reweighted least-squares algorithm. The dictionary atoms and the corresponding sparse coefficients are simultaneously estimated in the dictionary update step. Experimental results show that l(1)-K-SVD results in noise-robustness, faster convergence, and higher atom recovery rate than the method of optimal directions, K-SVD, and the robust dictionary learning algorithm (RDL), in Gaussian as well as non-Gaussian noise. For a fixed value of sparsity, number of dictionary atoms, and data dimension, l(1)-K-SVD outperforms K-SVD and RDL on small training sets. We also consider the generalized l(p), 0 < p < 1, data metric to tackle heavy-tailed/impulsive noise. In an image denoising application, l(1)-K-SVD was found to result in higher peak signal-to-noise ratio (PSNR) over K-SVD for Laplacian noise. The structural similarity index increases by 0.1 for low input PSNR, which is significant and demonstrates the efficacy of the proposed method. (C) 2015 Elsevier B.V. All rights reserved.

Fabrication and bio-functionalization of tetrahedral amorphous carbon thin films for bio sensor applications

Tetrahedral amorphous carbon (ta-C) thin films are a promising material for use as biocompatible interfaces in applications such as in-vivo biosensors. However, the functionalization of ta-C film surface, which is a pre-requisite for biosensors, remains a big challenge due to its chemical inertness. We have investigated the bio-functionalization of ta-C films fabricated under specific physical conditions through the covalent attachment of functional biomolecular probes of peptide nucleic acid (PNA) to ta-C films, and the effect of fabrication conditions on the bio-functionalization. The study showed that the functional bimolecular probes such as protected long-chain ω-unsaturated amine (TFAAD) can be covalently attached to the ta-C surface through a well-defined structure. With the given fabrication process, electrochemical methods can be applied to the detection of biomolecular interaction, which establishes the basis for the development of stable, label-free biosensors. © 2011 Elsevier B.V. All rights reserved.

Bio-inspired mechanics of reversible adhesion: Orientation-dependent adhesion strength for non-slipping adhesive contact with transversely isotropic elastic materials

Geckos and many insects have evolved elastically anisotropic adhesive tissues with hierarchical structures that allow these animals not only to adhere robustly to rough surfaces but also to detach easily upon movement. In order to improve Our understanding of the role of elastic anisotropy in reversible adhesion, here we extend the classical JKR model of adhesive contact mechanics to anisotropic materials. In particular, we consider the plane strain problem of a rigid cylinder in non-slipping adhesive contact with a transversely isotropic elastic half space with the axis of symmetry oriented at an angle inclined to the surface. The cylinder is then subjected to an arbitrarily oriented pulling force. The critical force and contact width at pull-off are calculated as a function of the pulling angle. The analysis shows that elastic anisotropy leads to an orientation-dependent adhesion strength which can vary strongly with the direction of pulling. This study may suggest possible mechanisms by which reversible adhesion devices can be designed for engineering applications. (C) 2006 Elsevier Ltd. All rights reserved.