A facile method for producing unoxidized, pristine graphene under biologically benign conditions is essential for widespread biomedical applications of graphene. Rate of exfoliation, scalability, high quality, controlled functionalization, size and large fl ake size are highly desired. Rapid production of biofunctionalized, micrometer size, and defect free, few layer graphene (FLG) is reported here. Further, we have systematically examined Kitchen Chemistry 101: Multigram Production of High Quality Biographene in a Blender with Edible ProteinsAjith Pattammattel and Challa Vijaya Kumar * A high yielding aqueous phase exfoliation of graphite to high quality graphene using edible proteins and kitchen chemistry is reported here. Bovine serum albumin (BSA), β-lactoglobulin, ovalbumin, lysozyme, and hemoglobin are used to exfoliate graphite and the exfoliation effi ciency depended on the sign and magnitude of the protein charge. BSA showed maximum exfoliation rate, facilitated graphite exfoliation in water, at room temperature, by turbulence/ shear force generated in a kitchen blender at exfoliation effi ciencies exceeding 4 mg mL −1 h −1. Raman spectroscopy and transmission electron microscopy indicated 3-5 layer, defect-free graphene of 0.5 µm size. Graphene dispersions loaded on a cellulose paper (650 µg cm −2 ) showed the fi lm conductivity of 32 000 S m −1 , which is much higher than graphene/polymer composites. Our method yielded ≈7 mg mL −1 , BSA-coated graphene with controllable surface charge, which is stable under wide ranges of pH (3.0-11) and temperature (5.0-50 °C), and in fetal bovine serum, for more than two months.These fi ndings may lead to the large scale production of graphene for biological applications.

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...

Nearly all implantable bioelectronics are powered by bulky batteries which limit device miniaturization and lifespan. Moreover, batteries contain toxic materials and electrolytes that can be dangerous if leakage occurs. Herein, an approach to fabricate implantable protein-based bioelectrochemical capacitors (bECs) employing new nanocomposite heterostructures in which 2D reduced graphene oxide sheets are interlayered with chemically modified mammalian proteins, while utilizing biological fluids as electrolytes is described. This protein-modified reduced graphene oxide nanocomposite material shows no toxicity to mouse embryo fibroblasts and COS-7 cell cultures at a high concentration of 1600 μg mL−1 which is 160 times higher than those used in bECs, unlike the unmodified graphene oxide which caused toxic cell damage even at low doses of 10 μg mL−1. The bEC devices are 1 μm thick, fully flexible, and have high energy density comparable to that of lithium thin film batteries. COS-7 cell culture is not affected by long-term exposure to encapsulated bECs over 4 d of continuous charge/discharge cycles. These bECs are unique, protein-based devices, use serum as electrolyte, and have the potential to power a new generation of long-life, miniaturized implantable devices.

Graphene oxide (GO) is being investigated extensively for enzyme and protein binding, but many enzymes bound to GO denature considerably and lose most of their activities. A simple, novel, and efficient approach is described here for improving the structures and activities of enzymes bound to GO such that bound enzymes are nearly as active as those of the corresponding unbound enzymes. Our strategy is to preadsorb highly cationized bovine serum albumin (cBSA) to passivate GO, and cBSA/GO (bGO) served as an excellent platform for enzyme binding. The binding of met-hemoglobin, glucose oxidase, horseradish peroxidase, BSA, catalase, lysozyme, and cytochrome c indicated improved binding, structure retention, and activities. Nearly 100% of native-like structures of all the seven proteins/enzymes were noted at near monolayer formation of cBSA on GO (400% w/w), and all bound enzymes indicated 100% retention of their activities. A facile, benign, simple, and general method has been developed for the biofunctionalization of GO, and this approach of coating with suitable protein glues expands the utility of GO as an advanced biophilic nanomaterial for applications in catalysis, sensing, and biomedicine.

High-nickel content cathode materials offer high energy density. However, the structural and surface instability may cause poor capacity retention and thermal stability of them. To circumvent this problem, nickel concentration-gradient materials have been developed to enhance high-nickel content cathode materials’ thermal and cycling stability. Even though promising, the fundamental mechanism of the nickel concentration gradient’s stabilization effect remains elusive because it is inseparable from nickel’s valence gradient effect. To isolate nickel’s valence gradient effect and understand its fundamental stabilization mechanism, we design and synthesize a LiNi0.8Mn0.1Co0.1O2 material that is compositionally uniform and has a hierarchical valence gradient. The nickel valence gradient material shows superior cycling and thermal stability than the conventional one. The result suggests creating an oxidation state gradient that hides the more capacitive but less stable Ni3+ away from the secondary particle surfaces is a viable principle towards the optimization of high-nickel content cathode materials.