This review highlights the application of lipases in the synthesis of pharmaceutically important small molecules and polymers for diverse applications.

Unusually photoluminescent undoped oligomers and doped electrically conducting polymers of 4-(3-Pyrrolyl) butyric acid have been enzymatically synthesized using the oxidoreductase soybean peroxidase as a catalyst. This biocatalytic approach provides a direct route to a fluorescent-undoped oligomer of pyrrole that requires no protection/deprotection chemistry. The synthesis is carried out in aqueous media that requires only monomer, enzyme, and hydrogen peroxide. The undoped oligomer exhibits stable emission properties and is highly sensitive to the presence of environmentally important metal ions, such as Co(II), Hg(II), and Cu(II) in solution. Electrically conducting polymers can also be obtained by adding a dopant to a buffered reaction solution prior to initiating the polymerization. Polymers doped with camphor-10-sulfonic acid exhibit conductivity values as high as 10(-2) S/cm. Additionally, polymers synthesized in the presence of a biobased cationic template, N, N, N-trimethylchitosan chloride, exhibit conductivity values that are an order of magnitude greater than polymers synthesized with the anionic polymeric template, poly(styrene sulfonic acid)-sodium salt. The biobased synthetic strategy described here is the first report of directly obtaining an undoped, fluorescent conjugated oligomer of a pyrrole in aqueous solution. Unlike conventional chemical catalysts, the enzyme does not dope the oligomer and therefore provides the opportunity to directly obtain fluorescent conjugated species. (C) 2014 Wiley Periodicals, Inc.

We report an easy and simple approach for making silver nanotubes (NTs) using electrospinning.

A series of two-photon (TP) active 4-dimethylaminocinnamoyl coumarins were synthesized. These compounds exhibit red shift in absorption and considerable Stokes shift in emission spectra in comparison to the parent coumarin. Large TP absorption cross-sections were measured for all the coumarins in dilute solutions. A correlation between the chemical structure and TP characteristics was established. TP confocal microscopy revealed that these coumarin derivatives can be internalized by cancer cells rendering them a potential candidate as a label in TP confocal imaging. (C) 2014 Elsevier B.V. All rights reserved.

Nanoparticles (NPs) with opposite charges of a donor polymer, poly(3-hexyl thiophene) (P3HT) and an acceptor molecule, phenyl-C61-butyric acid methyl ester (PCBM) were synthesized using simple miniemulsion technique. The NPs were examined by dynamic light scattering, atomic force microscopy and scanning electron microscopy to confirm the formation of the NPs. The NPs were assembled into thin films by spin-coating of a blend of the NPs dispersion. The built-up of a five layered film was monitored by UV-vis absorption spectroscopy. Our preliminary study demonstrated that a solar cell made from an annealed NP film can exhibit photovoltaic response. (C) 2014 Elsevier B.V. All rights reserved.

Dye-sensitized solar cells (DSSCs) were fabricated using photoanodes made from graphene–TiO2 nanocomposites. The dependence of the size of graphene sheets on the cell performance was investigated. The experimental results indicated that cells loaded with the smaller graphene sheets yielded larger enhancement. The smaller graphene sheets improved the dye adsorption, leading to higher conversion efficiency. The DSSC incorporated with graphene sheets of 184nm exhibited the largest enhancement in efficiency (∼49%) as compared to the cell without graphene.

We report the synthesis of a self organizable and water dispersible bis PEGylated (bis polyethyleneglycolated) curcumin (1) using an efficient synthetic method. Compound 1 forms nanoparticles on the order of 90 nm in water. Even though it forms nanoparticles, compound 1 interacts strongly with metal ions, Al+3, Cu+2, and Hg+2. Fluorescence and absorption spectroscopic techniques were employed to investigate the metal interactions of these nanoparticles. Al+3 and Cu+2 ions interact with compound 1 leading to enhancement and dramatic quenching in the fluorescence of the latter in 100% water, respectively. Addition of Hg+2 ions to compound 1 in water produces a ratiometric change in the absorption spectra of the nanoparticles. Although PEGylated curcumin derivatives were reported in the past, there have been no reports on their self organization into nanoparticles and extensive studies on their metal interaction properties in 100% water using its fluorescence and absorption properties. (C) 2013 Elsevier Ltd. All rights reserved.

Enzymatic synthesis of doped polypyrrole (PPy) complexes using oxidoreductases (specifically peroxidases) is very well established "green" methods for producing conducting polypyrrole. The importance of this approach is realized by the numerous potential opportunities of using PPy in biological applications. However, due to very high costs and low acid stability of these enzymes, there is need for more robust alternate biomimetic catalysts. Hematin, a hydroxyferriprotoporphyrin, has a similar iron catalytic active center like the peroxidases and has previously shown to catalyze polymerization of phenol monomers at pH 12. The insolubility of hematin due to extensive self-aggregation at low pH conditions has prevented its use in the synthesis of conjugated polymers. In this study, we have demonstrated the use of a micellar environment with sodium dodecylbenzenesulfonate (DBSA) for biomimetic synthesis of PPy. The micellar environment helps solubilize hematin, generating nanometer size reactors for the polymerization of pyrrole. The resulting PPy is characterized using UV-visible, Fourier transform infrared, and X-ray photoelectron spectroscopy and reveals the formation of an ordered PPy/DBSA complex with conductivities approaching 0.1 S/cm.

Two-photon (TP) fluorescence properties of an antioxidant and anti-tumor molecule, curcumin, were investigated. The two-photon absorption (TPA) action cross-section was measured in organic solvents and found to be 6 GM in tetrahydrofuran and 2 GM in dimethyl sulfoxide. The measured TPA cross-section is comparable to that of rhodamine 6G. One-photon and TP confocal microscopy has demonstrated that curcumin is internalized in cells and can be used for imaging applications. Our investigation indicates that curcumin is a viable biocompatible TP fluorescent marker.

Crosslinking of polymers using crosslinking agents has been widely utilized to further improve the mechanical and thermal properties of the polymers. We have explored various aliphatic and aromatic dicarboxylic acids such as malonic acid, glutaric acid, isophthalic acid, terephthalic acid and terephthaloyl chloride as crosslinking agents to crosslink polydimethylsiloxane copolymer [poly{poly(dimethylsiloxane-1000)-propylamine-5-aminoisophthaloyl}] to improve its flame retardant properties. We have also used nanoclays [Cloisite 20A, 2C18 MMT (dimethylditallowammonium-/ dimethyldioctadecylammonium-modified montmorillonite)] along with the crosslinker during crosslinking process to further reduce the flammability of the crosslinked polymers. Among all the crosslinkers investigated, isophthalic acid with the nanoclay was found to have the best performance for flame retardant applications. The present work provides a basis to further improve the performance of silicone-based polymers for the flame retardant applications.