A highly efficient, multifunctional, bioderived white-emitting hydrogel (biophosphor) consisting of crosslinked bovine serum albumin and three fluorescent dyes, Coumarin 460, fluorescein, and 5(6)-carboxy-x-rhodamine, is reported here. White emission is obtained upon excitation of the biophosphor at 365 nm with appropriate mole ratios of the above dyes. The CIE 1931 chromaticity coordinates of white emission with 365 nm excitation are (0.36, 0.37), and the correlated color temperature is 5300 K. Multifunctional nature of the biophosphor is also demonstrated. A UV-light-emitting-diode (361 nm) coated with this biophosphor, for example, indicates white emission (CIE 0.28, 0.31) with a half-life of 106 (±5) h. The white emission is also highly sensitive to pH over a broad range (pH 1-11). Incorporation of glucose oxidase and peroxidase in the biophosphor allows for the detection of glucose over a physiologically relevant range of 1.8-288 mg dL −1 . This is a unique, advanced biophosphor with LED and sensing applications, and it is the first example of a multifunctional, proteinaceous white emitter. molar absorptivity and quantum efficiency of emissive components is a significant challenge for systems that combine direct emission and sensitized emission via Förster resonance energy transfer (FRET) to produce white light. [6,7] Hydrogels are hydrophilic polymer networks [8] and are emerging as versatile new matrices for high-efficiency generation of white light using intermolecular energy transfer processes. The gel matrix improves energy transfer efficiency by rigidifying the orientation of the donor (D)-acceptor (A) pairs [9] and preventing their aggregation, which can lead to quenching. [10] Despite the advantageous properties of white-emitting hydrogels, implementation in a functional device and photostability were not systematically studied, and biodegradability has not been demonstrated. Additionally, white-emitting proteinbased hydrogels are not known other than a report of a gelatin hydrogel with chromaticity coordinates [0.26, 0.33], far from being coordinates of pure white emission [0.33, 0.33]. [2] To the best of our knowledge, there are no reports of a multifunctional, nontoxic, biodegradable, white-emitting protein hydrogel.BSA is inexpensive and readily available as a waste product of the meat industry. BSA has a large number of primary amines (59 lysine) and carboxylic acids (99 aspartic acid/glutamic acid), [11] which can be crosslinked under controlled conditions by carbodiimide chemistry to form a network of amide bonds without disrupting the intricate secondary structure of the protein. [12,13] The protein's secondary structure plays an important role for dye binding at the intended site and for enzyme activity retention, when enzymes are incorporated in the matrix for sensing or catalytic applications. We envisioned that this molecular network of BSA would result in a water-rich hydrogel with discrete sites for dye binding which would be suitable for the construction of a white-emitting gel.Previou...

Several key properties of catalase such as thermal stability, resistance to protease degradation, and resistance to ascorbate inhibition were improved, while retaining its structure and activity, by conjugation to poly(acrylic acid) (PAA, Mw 8000) via carbodiimide chemistry where the amine groups on the protein are appended to the carboxyl groups of the polymer. Catalase conjugation was examined at three different pH values (pH 5.0, 6.0, and 7.0) and at three distinct mole ratios (1:100, 1:500, and 1:1000) of catalase to PAA at each reaction pH. The corresponding products are labeled as Cat-PAA(x)-y, where x is the protein to polymer mole ratio and y is the pH used for the synthesis. The coupling reaction consumed about 60-70% of the primary amines on the catalase; all samples were completely water-soluble and formed nanogels, as evidenced by gel electrophoresis and electron microscopy. The UV circular dichroism (CD) spectra indicated substantial retention of protein secondary structure for all samples, which increased to 100% with increasing pH of the synthesis and polymer mole fraction. Soret CD bands of all samples indicated loss of ∼50% of band intensities, independent of the reaction pH. Catalytic activities of the conjugates increased with increasing synthesis pH, where 55-80% and 90-100% activity was retained for all samples synthesized at pH 5.0 and pH 7.0, respectively, and the Km or Vmax values of Cat-PAA(100)-7 did not differ significantly from those of the free enzyme. All conjugates synthesized at pH 7.0 were thermally stable even when heated to ∼85-90 °C, while native catalase denatured between 55 and 65 °C. All conjugates retained 40-90% of their original activities even after storing for 10 weeks at 8 °C, while unmodified catalase lost all of its activity within 2 weeks, under similar storage conditions. Interestingly, PAA surrounding catalase limited access to the enzyme from large molecules like proteases and significantly increased resistance to trypsin digestion compared to unmodified catalase. Similarly, negatively charged PAA surrounding the catalase in these conjugates protected the enzyme against inhibition by negatively charged inhibitors such as ascorbate. While Cat-PAA(100)-7 did not show any inhibition by ascorbate in the presence of 270 μM ascorbate, unmodified catalase lost ∼70% of its activity under similar conditions. This simple, facile, and rational methodology produced thermostable, storable catalase that is also protected from protease digestion and ascorbate inhibition and most likely prevented the dissociation of the multimer. Using synthetic polymers to protect and improve enzyme properties could be an attractive approach for making "Stable-on-the-Table" enzymes, as a viable alternative to protein engineering.

Cytochrome c–poly(acrylic acid) conjugates with 34-fold enhanced peroxidase activity due to acidification of enzyme microenvironment and suppression of wasteful intermediates.

The Virtual Atomic and Molecular Data Centre (VAMDC, http://www.vamdc.eu/) is a European-Union-funded collaboration between groups involved in the generation, evaluation, and use of atomic and molecular data. VAMDC aims to build a reliable, open, flexible and interoperable e-science interface to existing atomic and molecular data. The project will cover establishing the core consortium, the development and deployment of the infrastructure and the development of interfaces to the existing atomic and molecular databases. This paper describes the organisation of the project and the achievements during its first year.

Artificial antenna complexes built via self-assembly are reported here, which indicated excellent energy transfer efficiency, macroscopic organization, unprecedented thermal stability, and ease of formation.Our system consists of four fluorescent donor-acceptor dyes, double-helical DNA and cationized bovine serum albumin, all self-assembled on cover glass slips to form functional materials. These captured radiation in the range of 330-590 nm, and excitation of any of the donor dyes resulted in efficient emission from the terminal acceptor. Excitation spectra provided unequivocal proof of energy transfer via jumper dyes, and transfer was interrupted when one of the jumper dyes was omitted, another direct evidence for cascade energy transfer. The entire assembly indicated unusually high thermal stability and continued to function efficiently even after exposure to 80 C for >169 days, an important consideration for field applications. These unusually stable, high efficiency, multichromophoric, artificial antennas are the first of their kind to demonstrate self-assembled 4-dye energy cascade, converting blue photons to red photons. † Electronic supplementary information (ESI) available: Including experimental methods, characterization of modied BSA, uorescence, circular dichroism, etc. See Scheme 1 Artificial antenna complexes constructed from donors, acceptors, cationized BSA (cBSA), and DNA.This journal is

Enhancing the stability of enzymes for sensing or biocatalysis applications is still an unmet challenge. Ordinary paper is a very attractive support for anchoring enzymes but enzyme attachment to cellulose without surface activation is still another challenge. To make progress toward these goals, we developed a simple method to prepare highly active and stable enzyme-hydrogels within the mesh of the cellulose fibers of paper. A mixture of the desired enzyme, bovine serum albumin (BSA) and arginine were reacted with carbodiimide to form stable hydrogels. A set of critical concentrations (BSA([BSA] 0) ≥1 mM), [carbodiimide] 0 ≥ 100 mM and [amino acid] ≥ 100 mM) were required to form transparent hydrogels. The thermal reversibility of gelation proved that the gels are stabilized by non-covalent bonding interactions between the BSA oligomers that were formed via covalent interactions. Both dynamic light scattering and SDS-PAGE studies, under pre-gelation conditions, support idea that one BSA oligomeric unit contained 40-70 protein molecules. Scanning electron micrographs, thermogravimetry and swelling studies suggest that the formation of water cavities inside the cross-linked gel matrix, where the water mass was 7-8 times higher than that of the protein and the free amino acid used as a linker/spacer. Due to the higher water content and benign gelation conditions, active enzymes could be incorporated into the gel structure during the synthesis. Hydrogels, thus, embedded with glucose oxidase (GOx) and horseradish peroxide (HRP) showed catalytic activity towards glucose, where efficient channeling of hydrogen peroxide from GOx to HRP was observed (70% efficiency in initial rate compared to free enzymes in solution). Moreover, the enzymes retained their activity after pasting the hydrogel onto ordinary paper, which was demonstrated as a glucose sensing platform with a detection limit of 5 mM glucose. Trypsin embedded in the gel showed temperature dependent self-degradation by utilizing optimum protease activity at 37 • C. The temperature-triggered degradation of the gel can be used as a drug delivery vehicle, which was demonstrated using a reporter dye. The hydrogel made of a completely proteinaceous material that releases drugs at body temperature but bound to the matrix at room temperature (25 • C) is useful for noninvasive drug delivery platforms. The biocompatibility and non-thermal synthetic route for the hydrogel makes it a superior material for incorporation of temperature sensitive enzymes, drug molecules or nucleic acids, for a diverse set of applications.

In cells, actin and tubulin polymerization is regulated by nucleation factors, which promote the nucleation and subsequent growth of protein filaments in a controlled manner. Mimicking this natural mechanism to control the supramolecular polymerization of macromolecular monomers by artificially created nucleation factors remains a largely unmet challenge. Biological nucleation factors act as molecular scaffolds to boost the local concentrations of protein monomers and facilitate the required conformational changes to accelerate the nucleation and subsequent polymerization. An accelerated assembly of synthetic poly­(l-glutamic acid) into amyloid fibrils catalyzed by cationic silica nanoparticle clusters (NPCs) as artificial nucleation factors is demonstrated here and modeled as supramolecular polymerization with a surface-induced heterogeneous nucleation pathway. Kinetic studies of fibril growth coupled with mechanistic analysis demonstrate that the artificial nucleators predictably accelerate the supramolecular polymerization process by orders of magnitude (e.g., shortening the assembly time by more than 10 times) when compared to the uncatalyzed reaction, under otherwise identical conditions. Amyloid-like fibrillation was supported by a variety of standard characterization methods. Nucleation followed a Michaelis–Menten-like scheme for the cationic silica NPCs, while the corresponding anionic or neutral nanoparticles had no effect on fibrillation. This approach shows the effectiveness of charge–charge interactions and surface functionalities in facilitating the conformational change of macromolecular monomers and controlling the rates of nucleation for fibril growth. Molecular design approaches like these inspire the development of novel materials via biomimetic supramolecular polymerizations.