Described herein is a flexible and lightweight chemiresistor made of a thin film composed of overlapped and reduced graphene oxide platelets (RGO film), which were printed onto flexible plastic surfaces by using inkjet techniques. The RGO films can reversibly and selectively detect chemically aggressive vapors such as NO 2 , Cl 2 , etc. Detection is achieved, without the aid of a vapor concentrator, at room temperature using an air sample containing vapor concentrations ranging from 100 ppm to 500 ppb. Inkjet printing of RGO platelets is achieved for the first time using aqueous surfactant-supported dispersions of RGO powder synthesized by the reduction of exfoliated graphite oxide (GO), by using ascorbic acid (vitamin C) as a mild and green reducing agent. The resulting film is has electrical conductivity properties (s % 15 S cm À1 ) and has fewer defects compared to RGO films obtained by using hydrazine reduction.Graphene has emerged as an environmentally stable electronic material with exceptional thermal, mechanical, and electrical properties because of its two-dimensional sp 2 -bonded structure. [1,2] Although individual graphene sheets have been synthesized on various surfaces using chemical vapor deposition, [2,3] an important chemical route to bulk quantities of RGO involves the conversion of graphite into GO using strong oxidants, and then subsequent reduction of the dispersed GO into RGO using strong reducing agents (e.g., hydrazine). [4,5] The large available surface area of graphene makes it an attractive candidate for use as a chemiresistor for chemical and biological detection. There are a few reports on vapor detection using graphene films on interdigitated arrays, [6][7][8][9] and one interesting report on singlemolecule detection. [9] In recent reports on reversible NO 2 vapor detection using graphene, either the response/recovery time of the signal is long, [7] or efforts to improve the recovery cycle by increasing the temperature was complicated by a smaller sensor response.[6] Herein we describe a rugged and flexible sensor using inkjet-printed films of RGO on poly-(ethylene terephthalate) (PET) to reversibly detect NO 2 and Cl 2 vapors within an air sample at the parts per billion level, and demonstrate the use of ascorbic acid as a mild and effective alternative to hydrazine to reduce GO into RGO.Ascorbic acid reduction of dispersed graphene oxide into RGO is carried out by first preparing GO from graphite using the method reported by Hummers and Offeman, [10] and then dispersing it in water containing 1 % polyethylene glycol. Ascorbic acid powder (3 g) is added to a 3 mg mL À1 aqueous GO dispersion and heated to 80 8C for 1 hour, at which point the color changes from yellow-brown to black, signaling the conversion into RGO platelets (Figure 1 a). This RGO powder is suction filtered and washed with water, and then

Over the past 5 years, a new generation of highly potent and broadly neutralizing HIV-1 antibodies has been identified. These antibodies can protect against lentiviral infection in nonhuman primates (NHPs), suggesting that passive antibody transfer would prevent HIV-1 transmission in humans. To increase the protective efficacy of such monoclonal antibodies, we employed next-generation sequencing, computational bioinformatics, and structure-guided design to enhance the neutralization potency and breadth of VRC01, an antibody that targets the CD4 binding site of the HIV-1 envelope. One variant, VRC07-523, was 5-to 8-fold more potent than VRC01, neutralized 96% of viruses tested, and displayed minimal autoreactivity. To compare its protective efficacy to that of VRC01 in vivo, we performed a series of simian-human immunodeficiency virus (SHIV) challenge experiments in nonhuman primates and calculated the doses of VRC07-523 and VRC01 that provide 50% protection (EC 50 ). VRC07-523 prevented infection in NHPs at a 5-fold lower concentration than VRC01. These results suggest that increased neutralization potency in vitro correlates with improved protection against infection in vivo, documenting the improved functional efficacy of VRC07-523 and its potential clinical relevance for protecting against HIV-1 infection in humans. IMPORTANCEIn the absence of an effective HIV-1 vaccine, alternative strategies are needed to block HIV-1 transmission. Direct administration of HIV-1-neutralizing antibodies may be able to prevent HIV-1 infections in humans. This approach could be especially useful in individuals at high risk for contracting HIV-1 and could be used together with antiretroviral drugs to prevent infection. To optimize the chance of success, such antibodies can be modified to improve their potency, breadth, and in vivo half-life. Here, knowledge of the structure of a potent neutralizing antibody, VRC01, that targets the CD4-binding site of the HIV-1 envelope protein was used to engineer a next-generation antibody with 5-to 8-fold increased potency in vitro. When administered to nonhuman primates, this antibody conferred protection at a 5-fold lower concentration than the original antibody. Our studies demonstrate an important correlation between in vitro assays used to evaluate the therapeutic potential of antibodies and their in vivo effectiveness.

Optimizing amino acid conformation and identity is a central problem in computational protein design. Protein design algorithms must allow realistic protein flexibility to occur during this optimization, or they may fail to find the best sequence with the lowest energy. Most design algorithms implement side-chain flexibility by allowing the side chains to move between a small set of discrete, low-energy states, which we call rigid rotamers. In this work we show that allowing continuous side-chain flexibility (which we call continuous rotamers) greatly improves protein flexibility modeling. We present a large-scale study that compares the sequences and best energy conformations in 69 protein-core redesigns using a rigid-rotamer model versus a continuous-rotamer model. We show that in nearly all of our redesigns the sequence found by the continuous-rotamer model is different and has a lower energy than the one found by the rigid-rotamer model. Moreover, the sequences found by the continuous-rotamer model are more similar to the native sequences. We then show that the seemingly easy solution of sampling more rigid rotamers within the continuous region is not a practical alternative to a continuous-rotamer model: at computationally feasible resolutions, using more rigid rotamers was never better than a continuous-rotamer model and almost always resulted in higher energies. Finally, we present a new protein design algorithm based on the dead-end elimination (DEE) algorithm, which we call iMinDEE, that makes the use of continuous rotamers feasible in larger systems. iMinDEE guarantees finding the optimal answer while pruning the search space with close to the same efficiency of DEE. Availability: Software is available under the Lesser GNU Public License v3. Contact the authors for source code.

Described herein is a flexible and lightweight chemiresistor made of a thin film composed of overlapped and reduced graphene oxide platelets (RGO film), which were printed onto flexible plastic surfaces by using inkjet techniques. The RGO films can reversibly and selectively detect chemically aggressive vapors such as NO 2 , Cl 2 , etc. Detection is achieved, without the aid of a vapor concentrator, at room temperature using an air sample containing vapor concentrations ranging from 100 ppm to 500 ppb. Inkjet printing of RGO platelets is achieved for the first time using aqueous surfactant-supported dispersions of RGO powder synthesized by the reduction of exfoliated graphite oxide (GO), by using ascorbic acid (vitamin C) as a mild and green reducing agent. The resulting film is has electrical conductivity properties (s % 15 S cm À1 ) and has fewer defects compared to RGO films obtained by using hydrazine reduction.Graphene has emerged as an environmentally stable electronic material with exceptional thermal, mechanical, and electrical properties because of its two-dimensional sp 2 -bonded structure. [1,2] Although individual graphene sheets have been synthesized on various surfaces using chemical vapor deposition, [2,3] an important chemical route to bulk quantities of RGO involves the conversion of graphite into GO using strong oxidants, and then subsequent reduction of the dispersed GO into RGO using strong reducing agents (e.g., hydrazine). [4,5] The large available surface area of graphene makes it an attractive candidate for use as a chemiresistor for chemical and biological detection. There are a few reports on vapor detection using graphene films on interdigitated arrays, [6][7][8][9] and one interesting report on singlemolecule detection. [9] In recent reports on reversible NO 2 vapor detection using graphene, either the response/recovery time of the signal is long, [7] or efforts to improve the recovery cycle by increasing the temperature was complicated by a smaller sensor response.[6] Herein we describe a rugged and flexible sensor using inkjet-printed films of RGO on poly-(ethylene terephthalate) (PET) to reversibly detect NO 2 and Cl 2 vapors within an air sample at the parts per billion level, and demonstrate the use of ascorbic acid as a mild and effective alternative to hydrazine to reduce GO into RGO.Ascorbic acid reduction of dispersed graphene oxide into RGO is carried out by first preparing GO from graphite using the method reported by Hummers and Offeman, [10] and then dispersing it in water containing 1 % polyethylene glycol. Ascorbic acid powder (3 g) is added to a 3 mg mL À1 aqueous GO dispersion and heated to 80 8C for 1 hour, at which point the color changes from yellow-brown to black, signaling the conversion into RGO platelets (Figure 1 a). This RGO powder is suction filtered and washed with water, and then

The cystic fibrosis transmembrane conductance regulator (CFTR) is an epithelial chloride channel mutated in patients with cystic fibrosis (CF). The most prevalent CFTR mutation, ΔF508, blocks folding in the endoplasmic reticulum. Recent work has shown that some ΔF508-CFTR channel activity can be recovered by pharmaceutical modulators (“potentiators” and “correctors”), but ΔF508-CFTR can still be rapidly degraded via a lysosomal pathway involving the CFTR-associated ligand (CAL), which binds CFTR via a PDZ interaction domain. We present a study that goes from theory, to new structure-based computational design algorithms, to computational predictions, to biochemical testing and ultimately to epithelial-cell validation of novel, effective CAL PDZ inhibitors (called “stabilizers”) that rescue ΔF508-CFTR activity. To design the “stabilizers”, we extended our structural ensemble-based computational protein redesign algorithm to encompass protein-protein and protein-peptide interactions. The computational predictions achieved high accuracy: all of the top-predicted peptide inhibitors bound well to CAL. Furthermore, when compared to state-of-the-art CAL inhibitors, our design methodology achieved higher affinity and increased binding efficiency. The designed inhibitor with the highest affinity for CAL (kCAL01) binds six-fold more tightly than the previous best hexamer (iCAL35), and 170-fold more tightly than the CFTR C-terminus. We show that kCAL01 has physiological activity and can rescue chloride efflux in CF patient-derived airway epithelial cells. Since stabilizers address a different cellular CF defect from potentiators and correctors, our inhibitors provide an additional therapeutic pathway that can be used in conjunction with current methods.