Development of injectable high molecular weight hyaluronic acid hydrogels for cartilage regeneration

The study focuses on developing hyaluronic acid (1200 kilo Dalton) hydrogels for cartilage regeneration. In spite of being highly biocompatible; a large amount of water absorption and easily degrading nature restricts the use of hyaluronic acid in the field of tissue regeneration. This can be rectified by crosslinking hyaluronic acid with a crosslinking agent such as divinyl sulfone; which results in a biocompatible hydrogel with superior rheological properties. Different amounts of divinyl sulfone have been used for crosslinking hyaluronic acid to get three types of hydrogels with differing properties. Swelling studies, rheology analysis, enzymatic degradation and scanning electron microscopic analysis were conducted on all the different types of hydrogels prepared. Viscoelastic properties of the hydrogel were analyzed so that a hydrogel with better elastic property and stability is obtained. Scanning electron microscopy was used to study the morphology of the HA hydrogels. The cytotoxicity testing was conducted to prove the non-toxic nature of the hydrogels and cell culture studies using adipose mesenchymal stem cells showed better adhesion and proliferation properties in all the three hydrogels. Thus hyaluronic acid hydrogel makes a promising material for cartilage regeneration.     

Group-selective antibodies based fluorescence immunoassay for monitoring opiate drugs

A novel carboxylic acid derivative of monoacetylmorphine (MAM-COOH) was synthesized and conjugated with bovine serum albumin (BSA) for generating polyclonal antibodies against the target molecule heroin and its major metabolites. The conjugate was characterized by fluorescence spectroscopy, polyacrylamide gel electrophoresis, and mass spectrometry to confirm the extent of haptenization of the carrier protein. A high titer (1:64,0000) of antibody was obtained by using the conjugate with an optimum protein/hapten molar ratio of 1:100. The generated antibody showed good binding affinity with heroin and its metabolites monoacetylmorphine (MAM) and morphine. The relative affinity constant (K (aff)) of the antibody was 3.1 x 10(7) l mol(-1), and the IC(50) values obtained for heroin, MAM, morphine, and codeine were 0.01, 0.013, 0.012, and 0.014 ng ml(-1), respectively. A fluorescence-based competitive inhibition immunoassay procedure was developed for the estimation of heroin and its major metabolites in standard and biofludic samples over a concentration range up to 0.01 ng ml(-1) with good signal reproducibility (p < 0.05). The method can be used as a convenient quantitative tool for the sensitive screening of major metabolites of heroin in biological samples.     

Thermal stability of magnesium-rich primers based on glycidyl carbamate resins

Coatings of outstanding thermal stability were obtained by the combination of two novel technologies, that of a magnesium-rich primer and a silane-modified glycidyl carbamate binder. While conducting a study to evaluate the new binder system with respect to properties of the magnesium-rich primer, during thermogravimetric analysis of samples, previously unobserved and unexpected properties were noted. The samples transformed into an intact solid residue, with the amount of the residual char ranging between 40 and 90% weight depending on the pigment volume concentration (PVC) of the magnesium particles in the composition. It appears that the hitherto unobserved property is essentially a function of the metallic pigment particles in the coating. The discovery of the exceptional thermal stability potentially increases the range of application for these primers and these can be further developed for use as a thermal barrier coating.     

A chemostat model of resource competition and allelopathy

Presented is a chemostat model in which one microbial population excretes a poison that increases the mortality of another, with toxin production increasing as the growth rate of the toxic species decreases. The model is intended to explore the role of allelopathy in blooms of harmful algae, such as red tide (Karenia brevis) and golden algae (Prymnesium parvum). This study introduces the model and its biological basis, and proceeds to the analysis of its asymptotic states. All theoretical results are supported by a set of numerical simulations. A discussion of biological conclusions and similarities to other mathematical models is also presented.     

Qualitative and Quantitative Standardization of Myrica esculenta Buch.-Ham. Stem Bark by Use of HPTLC

JPC – Journal of Planar Chromatography – Modern TLC - Bark of Myrica esculenta Buch.-Ham., commonly known as ‘Kaphal’ in indigenous systems of medicine, is used for...     

Synthesis of Maleimide-End Functionalized Star Polymers and Multimeric Protein-Polymer Conjugates

Protein-polymer conjugates exhibit superior properties to unmodified proteins, generating a high demand for these materials in the fields of medicine, biotechnology, and nanotechnology. Multimeric conjugates are predicted to surpass the activity of monomeric conjugates. Herein, we report a straightforward method to synthesize multimeric polymer-conjugates. Four armed poly(N-isopropylacrylamide) (pNIPAAm) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of a tetra-functionalized trithiocarbonate chain transfer agent (CTA). The polymer molecular weight, architecture and polydispersity index (PDI) were verified by gel permeation chromatography (GPC), dynamic light scattering gel permeation chromatography (DLS-GPC), and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. This approach afforded well-defined polymers (PDI's < 1.06) and the ability to target various molecular weights. Maleimide functional groups were introduced at the chain ends by heating the polymers in the presence of a furan-protected azo-initiator. This allowed for site-specific conjugation of V131C T4 lysozyme to the polymers to generate multimeric protein-polymer conjugates. MALDI-TOF mass spectrometry, electrospray ionization gas-phase electrophoretic-mobility macromolecule analysis (ESI-GEMMA), gel electrophoresis, and liquid chromatography tandem mass spectrometry (LC-MS/MS) of the trypsin digests demonstrated that multimeric protein-polymer conjugates had formed. This simple strategy provides ready access to star protein-polymer conjugates for application in the fields of drug discovery, drug delivery, and nanotechnology.     

A microfluidic "baby machine" for cell synchronization

Common techniques used to synchronize eukaryotic cells in the cell cycle often impose metabolic stress on the cells or physically select for size rather than age. To address these deficiencies, a minimally perturbing method known as the "baby machine" was developed previously. In the technique, suspension cells are attached to a membrane, and as the cells divide, the newborn cells are eluted to produce a synchronous population of cells in the G1 phase of the cell cycle. However, the existing "baby machine" is only suitable for cells which can be chemically attached to a surface. Here, we present a microfluidic "baby machine" in which cells are held onto a surface by pressure differences rather than chemical attachment. As a result, our method can in principle be used to synchronize a variety of cell types, including cells which may have weak or unknown surface attachment chemistries. We validate our microfluidic "baby machine" by using it to produce a synchronous population of newborn L1210 mouse lymphocytic leukemia cells in G1 phase.     

Unexpected formation of hydroxybiphenylmethane derivatives and some new observations on Labat test

An unexpected synthesis of symmetrical hydroxybiphenylmethanes involving the reaction of 2-hydroxyphenyl benzyl ketones with ethoxymethyl chloride has been observed. Some new interesting observations of Labat test on colorimetric detection of bichalconyloxy, bichalconyl and biflavonylmethanes having oxygenated ortho positions are presented.     

A facile method of producing femtoliter metal cups by pulsed laser ablation

Cuplike structures of Au, Ag, Cu, Zn, Nb, Cd, Al, In, and Sn in the size range of 300 nm to a few micrometers with an internal volume of a few femtoliters have been produced by the laser ablation of metal targets in a vacuum, by optimizing, in each case, the laser fluence and the substrate temperature. The metal droplets impinging on the substrate seem to undergo a hydraulic jump driven by the surface tension forces before solidifying into cups. The cups are robust and can be functionalized with biomarkers, filled with nanoparticle sols, oxidized to crucibles, or detached from the substrate without causing any deformation. We envisage their potential applications as femtoliter metal containers.