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The present study describes the formation of copolymers of linear and branched PEIs (25 kDa each). These polyethylenimines (bPEI and IPEI) were crosslinked with each other to obtain branched-linear (BL) PEI copolymers using epichlorohydrin as a crosslinker in two steps. First, IPEI was reacted with epichlorohydrin to form IPEI-chlorohydrin (CHL) and subsequently, bPEI was grafted onto CHL in basic medium by in situ generation of epoxy functionalities. The two PEIs were crosslinked by varying the weight ratio of bPEI while keeping the amount of IPEI fixed. The ratio of two PEIs (1:1, 2:1, 3:1, 4:1 and 5:1) and crosslinking percentage of epichlorohydrin (5, 10, 15 and 20%) appeared as the main parameters to have affected the transfection efficiency. The lead conjugate/DNA complex was tested for in vivo transgene expression in Balb/c mice and was found to show maximum expression in the spleen.

A new protocol has been described for solid phase preparation of 3′- and 5′-aminooxylalkylated oligonucleotides using commercially available reagents. This involves attachment of linker 4 either with an LCAA-CPG support via succinoylation followed by synthesis (3′-aminooxyalkylated oligomers) or formation of its phosphoramidite 6 followed by coupling with desired oligomer (for generating 5′-aminooxyalkylated oligomers). Both the routes produced modified oligonucleotides in sufficiently high yields and purity (on HPLC) via conventional oligonucleotide synthesis on an automated synthesizer and deprotection step using aqueous ammonia (16 h, 60 °C). Aminooxyalkylated oligonucleotides were used to construct microarrays on glass surface (biochips). The performance of the biochips was evaluated by immobilizing modified oligonucleotides on epoxylated glass microslides under different sets of conditions with respect to pH, temperature and time. Further, the constructed microarrays were successfully used for detection of nucleotide mismatches and bacterial typhoid.

A synthesis of labeled oligonucleotides incorporating a new chemically cleavable linker (III) via a two-step method is described. The labeled oligomers obtained after cleavage and deprotection reactions [treatment with anhydrous tert-butylamine and dry methanol, 1:1 (v/v) for 12 h at room temperature, and lyophilization followed by subsequent reaction with aq NH4OH and methylamine (40%), 1:1 (v/v) for 5 min at 65 °C] were analyzed by RP-HPLC. A distinctive feature of this protocol is that free oligomers can be recovered from their labeled analogs under mild conditions (0.2 M NaOH containing 0.5 M NaCl over 30 min at room temperature) and are comparable to the corresponding standard oligonucleotides (HPLC).

Polypropylene and polyethylene surfaces are activated by introducing an active functional group through 1-fluoro-2 nitro-4-azidobenzene by UV irradiation. Horseradish peroxidase and glucose oxidase are immobilized onto the activated surfaces, simply by incubating the enzymes at 37 degrees C. When untreated surfaces are used, insignificant immobilization of the enzymes is observed.

Intracellular nature and diversified locations of infectious and parasitic diseases such as leishmaniasis, trypanosomiasis, tuberculosis and hepatitis B and C pose a significant global burden and challenge to the scientists working in the area of drug discovery and drug delivery. The macrophages and hepatocytes are considered as potential target sites as they together play an important role in various infectious diseases. The present study scrutinizes the applicability of a natural biopolymer-based chemical vectors, capable of targeting both macrophages and hepatocytes, that can form a complex with plasmid and administer it into cells to produce a desired protein. The investigations were made to develop a novel series of gene carriers by conjugating depolymerized galactomannan (guar gum), a biocompatible polysaccharide with low molecular weight branched PEI (LMWP). A series of conjugates were developed and characterized using physicochemical techniques. All the GP/pDNA complexes showed significantly higher transfection efficiency with GP-3/pDNA, one of the best formulations, showed ~2.0-7.7-folds higher transfection efficacy when compared with the standard transfection reagents. Further, GP-3/pDNA displayed significantly higher target specific transfection efficiency under both in vitro and in vivo conditions. The data demonstrate the potential of GP vectors to deliver nucleic acids simultaneously to macrophages and hepatocytes in gene delivery applications.

Steady state photochemistry of vitamin K 1 has been examined using a 1 H nuclear magnetic resonance probe on solutions in CDCl 3 , acetone- d 6 , benzene- d 6 and acetonitrile- d 3 , and a UV probe on solutions in acetone, pentane and ethanol. A rationale for formation of the major photoproduct, i.e. chromenol ( 1 ), based on electron transfer from the side-chain olefinic bond to the naphthoquinone moiety in vitamin K 1 , has been suggested. The new mechanistic scheme implicates, inter alia , quinone methide ( 6 ) as the precursor of 1 . Attempted separation of photolysis mixture using flash chromatography has led to isolation of 9 and an oxygen adduct 10 of chromenol ( 1 ). The photoconversion of the vitamin is accelerated with catalytic amounts of triethylamine.

The development of oligonucleotide-based microarrays (biochips) is a major thrust area in the rapidly growing biotechnology industry, which encompasses a diverse range of research areas including genomics, proteomics, computational biology, and pharmaceuticals, among other activities. Microarray experiments have proved to be unique in offering cost-effective and efficient analysis at the genomic level. In the last few years, biochips have gained increasing acceptance in the study of genetic and cellular processes. As the increase in experimental throughput has posed many challenges to the research community, considerable progress has been made in the advancement of microarray technology. In this review, chemical strategies for immobilization of oligonucleotides have been highlighted with special emphasis on post-synthetic immobilization of oligonucleotides on glass surface. The major objective of this article is to make the researchers acquainted with some most recent advances in this area.

A new protocol has been developed for incorporation of a photoisomerizable azobenzene moiety into synthetic stereo-enriched [Rp] and [Sp] PS-oligonucleotides. The azobenzene pendant is attached at pre-selected positions in internucleotidic phosphorothioate oligonucleotides of both [Rp] and [Sp] diastereomers using a novel reagent, N-iodoacetyl-p-aminoazobenzene, 1. The modified oligomers are purified on HPLC, characterized by LC–MS, and examined for their thermal and photoisomerization properties. The azobenzene moiety imparts greater stability to oligomer duplexes in (E) N N configuration as compared to (Z) configuration. The placement of the azobenzene pendant close to 5′-terminus (n − 1) and 3′-terminus of the modified PS-oligos contributes maximum stability to the duplex while a gradual decline in stability occurs with azobenzene moving toward middle of the duplex. Circular Dichroism studies reveal that the chiral environment at the phosphorus center of the PS-oligos does not alter the global conformation of the DNA duplex as such, suggesting conservation of conformation of the modified DNA strands.

A simple photoresponsive azo-dextran polymer has been investigated for its ability to act as a nanogel drug carrier. Self aggregation of the azo-dextran polymer leads to the formation of nanogels, AD (5 and 10) in aqueous media, which were characterized by TEM and DLS. When examined under UV light (365 nm), the unloaded nanogels, which were observed to be in the range of 120-290 nm, show dependence on the degree of crosslinking, pH and ionic concentration of the dispersed media. Nanogels, AD (5 and 10), have been loaded with a model fluorophore, rhodamine B and a drug, aspirin, by freeze drying an aqueous dispersion of the nanogels in the presence of the substrate dissolved in water or PBS buffer. The release pattern of the encapsulated bio-active molecules from these nanogels was regulated by (trans-cis) photoisomerization of the azobenzene moiety present in the crosslinker. A comparison of the release behavior of the loaded (rhodamine, aspirin) AD (5 and 10) nanogels reveal that the rate of release of the encapsulated active molecules from the nanogels was slower when the azo moiety was in E-configuration as compared to that the azo in the Z-configuration. The in vitro release behavior of drug from these polymeric micellar systems is revelative of the potential of the nanogels for targeted drug delivery in nanomedicine.

A two-step general method for labeling of synthetic oligonucleotides is described. The protocol employs a cleavable universal linker, 5'-O-(4,4'-dimethoxytrityl)-3'-O-benzoyl-2'-O-(2-cyanoethyl-N,N-diisopropyl)-uridine phosphoramidite, to effect coupling to polymer-bound oligonucleotide chains. Sequentially, coupling with commercially available phosphoramidite reagent of an appropriate label (Biotin, HEX etc.) in an automated DNA synthesizer is carried out. The labeled oligomers, obtained after cleavage and deprotection reactions, are analyzed on RP-HPLC. A distinctive feature of this protocol is the recovery of free oligomers from their labeled analogs under mild conditions. The oligomers obtained are comparable to the corresponding standard oligonucleotides (HPLC).

A simple and mild procedure is developed for the preparation of an activated polymer surface, used for immobilization of a protein ligand through a covalent linkage. Activation of the polymer surface is carried out by attaching an active functional group through 1-fluoro-2-nitro-4-azidobenzene (FNAB). UV irradiation of FNAB transforms its azido group into a highly reactive nitrene, which binds with the inert polymer surface, whereas the active fluoro group of FNAB, now part of the polymer, remains intact. Covalent linkage between the ligand and the inert surface is established through this active fluoro group in a thermochemical reaction. The photochemical step is carried out under dry conditions to exclude the possibility of undesirable reactions between the solvent and the highly reactive nitrene. The method can be used for activation of different inert polymer surfaces having carbon hydrogen bonds. The efficacy of our method is demonstrated by immobilizing horseradish peroxidase on an activated polystyrene surface. The enzyme, immobilized through the photolinker, is found to give a twofold increase in absorbance with the substrate as compared to the directly adsorbed enzyme. The method may have many applications in the preparation of bioreactors, biostrips, and biosensors, and in diagnostic tests involving the ELISA technique.

The tacticity and number average sequence length of like ( n o ), meso ( n m ) and racemic ( n r ) acrylonitrile (AN) triad units in polyacrylonitrile (PAN) prepared in both water and water—acetone (2:1 v/v) media and AN-3-chloro, 2-hydroxypropyl acrylate/methacrylate, AN-2-bromoethyl methacrylate and AN-2-chloroethyl acrylate copolymers have been calculated using 13C n.m.r. spectra of the polymer solutions concerned at a field strength of 24.99 MHz. The spectra reveal that PAN prepared in water medium has a greater percentage (33.4%) of isotactic units than PAN prepared in water-acetone (2:1 v/v) medium (28.3%). The tacticity distribution of AN sequences in PAN and the copolymers is found to be random ( n m ⋍ n r ⋍2.0 ) and the number average sequence length of AN sequences in a copolymer containing 14.8 mole% of 3-chloro, 2-hydroxypropyl methacrylate was 15.2.

A new synthesis of DL-ar-turmerone starting from DL-curcumone is described. The aromatic ketone DL-ar-turmerone (I) occurs with turmerone (II) a monocyclic sesquiterpene ketone, as chief component of the essential oil from the rhizomes of Curcuma longa Linn.