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Decellularized extracellular matrix scaffold, widely utilized for organ engineering, often undergoes matrix decomposition after transplantation and produces byproducts that cause inflammation, leading to clinical failure. Here we propose a strategy using nano-graphene oxide to modify the biophysical properties of decellularized liver scaffolds. Notably, we demonstrate that scaffolds crosslinked with nano-graphene oxide show high resistance to enzymatic degradation via direct inhibition of matrix metalloproteinase activity and increased mechanical rigidity. We find that M2-like macrophage polarization is promoted within the crosslinked scaffolds, which reduces graft-elicited inflammation. Moreover, we show that low activities of matrix metalloproteinases, attributed to both nano-graphene oxide and tissue inhibitors of metalloproteinases expressed by M2c, can protect the crosslinked scaffolds against in vivo degradation. Lastly, we demonstrate that bioengineered livers fabricated with the crosslinked scaffolds remain functional, thereby effectively regenerating damaged livers after transplantation into liver failure mouse models. Overall, nano-graphene oxide crosslinking prolongs allograft survival and ultimately improves therapeutic effects of bioengineered livers, which offer an alternative for donor organs. Bioengineered livers using decellularized scaffolds have been considered as an alternative to donor organs. Here, the authors modulate biophysical properties of decellularized scaffolds by crosslinking with nano-graphene oxide, thereby greatly enhancing therapeutic efficacy of bioengineered livers. [ABSTRACT FROM AUTHOR]

Stomatal function can be used effectively to monitor plant hydraulics, photosensitivity, and gas exchange. Current approaches to measure single stomatal aperture, such as mold casting or fluorometric techniques, do not allow real time or persistent monitoring of the stomatal function over timescales relevant for long term plant physiological processes, including vegetative growth and abiotic stress. Herein, we utilize a nanoparticle-based conducting ink that preserves stomatal function to print a highly stable, electrical conductometric sensor actuated by the stomata pore itself, repeatedly and reversibly for over 1 week. This stomatal electro-mechanical pore size sensor (SEMPSS) allows for real-time tracking of the latency of single stomatal opening and closing times in planta, which we show vary from 7.0 ± 0.5 to 25.0 ± 0.5 min for the former and from 53.0 ± 0.5 to 45.0 ± 0.5 min for the latter in Spathiphyllum wallisii. These values are shown to correlate with the soil water potential and the onset of the wilting response, in quantitative agreement with a dynamic mathematical model of stomatal function. A single stoma of Spathiphyllum wallisii is shown to distinguish between incident light intensities (up to 12 mW cm−2) with temporal latency slow as 7.0 ± 0.5 min. Over a seven day period, the latency in opening and closing times are stable throughout the plant diurnal cycle and increase gradually with the onset of drought. The monitoring of stomatal function over long term timescales at single stoma level will improve our understanding of plant physiological responses to environmental factors. [ABSTRACT FROM AUTHOR]

Caffeic acid (CA) is one of the antioxidants found in plants, which protects vascular cells against vascular injuries from oxidative stress. In our previous study, caffeoyl-prolyl-histidine amide (CA-L-Pro-L-His-NH; CA-PH; a CA derivative) was synthesized, which exhibited a strong antioxidant activity with sufficient stability. In this study, we investigated the role of CA-PH in vascular smooth muscle cells (VSMCs) and confirmed the enhanced antioxidant activity of CA-PH compared with that of CA. In in vitro tube assays, CA-PH showed a higher free-radical-scavenging activity and lipid-peroxidation-inhibition activity than those of CA. In VSMCs, CA-PH significantly reduced hydrogen peroxide-induced ROS generation and increased the expression of heme oxygenase-1. Moreover, CA-PH effectively inhibited the platelet-derived growth factor-induced cellular proliferation of VSMCs, which was confirmed by a decrease in the expression of the proliferating cell nuclear antigen and the phosphorylation of Akt. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is an emerging luminescent nanomaterial with photostable and unique photoluminescence (PL) in the visible and near-infrared region. Herein, a GO PL-based optical biosensor consisting of a luminescent GO donor covalently linked with a peptide-quencher complex is reported for the simple, rapid, and sensitive detection of proteases. To this end, the quenching efficiency of various candidate quenchers of GO fluorescence, such as metalloprotoporphyrins and QXL570, are examined and their quenching mechanisms investigated. A fluorescence resonance energy transfer-based quencher, QXL570, is found to be much more effective for quenching the intrinsic fluorescence of GO than other charge transfer-based quenchers. The designed GO-peptide-QXL system is then able to sensitively detect specific proteases-chymotrypsin and matrix metalloproteinase-2-via a 'turn-on' response of quenched GO fluorescence after proteolytic cleavage of the quencher. Finally, the GO-peptide-QXL hybrid successfully detects MMP-2 secreted from living cells-human hepatocytes HepG2-with high sensitivity. [ABSTRACT FROM AUTHOR]

ABSTRACT Conjugation of an oligopeptide or an amino acid to bioactive compounds is one of the simplest chemical modifications to modulate the biological functions of the compounds. Recently, numerous methods have been proposed for the modification of their properties, including the alteration of their chemical and physical properties, and of their original bioactivities. We review the current knowledge of the adaptability of oligopeptide or amino acid conjugation for modulating the biological activities of biomolecules. © 2013 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 584-591, 2013. [ABSTRACT FROM AUTHOR]

Tyrosinase plays a critical role in the early stages of the melanin synthetic pathway by catalyzing the oxidation of the substrate. Therefore, tyrosinase inhibitors have been intensively studied in both cosmetic and food industries to develop hypopigmentary agents and prevent enzymatic browning in food. Previously, we reported that kojic acid-amino acid amide (KA-AA-NH2) showed enhanced tyrosinase inhibitory activity compared with kojic acid alone, but this was not observed in a cell test because of poor cell permeability. To enhance cell permeability, we prepared copper and zinc complexes of KA-AA-NH2 and characterized them using FT-IR spectroscopy, ESI-MS spectrometry, and inductively coupled plasma analysis. We then showed that KA-AA-NH2 copper complexes exhibited melanogenesis inhibitory activity in Mel-Ab cells. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Antioxidants have become an important subject of study as an active ingredient for cosmetics and preservatives for food. We synthesized antioxidative peptide conjugates of hydroxycinnamic acids (HCAs) such as ferulic acid (FA), caffeic acid (CA), and sinapic acid (SA) by SPPS method. We measured their potential antioxidant properties by 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging test and lipid autoxidation inhibition test. When the antioxidative peptides, such as glutathione analogue (GS(Bzl)H) and carnosine (CAR), were conjugated to HCAs, their antioxidative activities were enhanced significantly. CA-peptides exhibited the highest free radical scavenging activity by the DPPH test, and showed good antioxidative activity in the lipid autoxidation test. FA- and SA-peptides showed excellent antioxidative activity in the lipid autoxidation test. Furthermore, we demonstrated a synergistic antioxidative activity of HCA-peptide conjugates by comparing their antioxidative activity with that of a simple mixture of HCAs and the antioxidant peptides. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Excessive accumulation of melanin can cause skin pigmentation disorders, which may be accompanied by significant psychological stress. Although many natural and synthetic products have been developed for the regulation of melanogenesis biochemistry, the management of unwanted skin pigmentation remains challenging. Herein, we investigated the potential hypopigmenting properties of peptide sequences that originated from milk proteins such as ĸ-casein and β-lactoglobulin. These proteins are known to inhibit melanogenesis and their hydrolysates are reported as antioxidant peptides. We synthesize tetrapeptide fragments of the milk protein hydrolysates and investigate the amino acids that are essential for designing peptides with tyrosinase inhibitory and antioxidant activities. We found that the peptide methionine-histidine-isoleucine-arginine amide sufficiently inhibits mushroom tyrosinase activity, shows potent antioxidant activity and effectively impedes melanogenesis in cultured melanocytes via cooperative biological activities. Our findings demonstrate the potential utility of the bioactive tetrapeptide from milk proteins as a chemical alternative to hypopigmenting agents. [ABSTRACT FROM AUTHOR]

A correction to the article "Direct Identification of On-Bead Peptides Using Surface-Enhanced Raman Spectroscopic Barcoding System for High-Throughput Bioanalysis" that was published in a 2015 issue, is presented.

Recently, preparation and screening of compound libraries remain one of the most challenging tasks in drug discovery, biomarker detection, and biomolecular profiling processes. So far, several distinct encoding/decoding methods such as chemical encoding, graphical encoding, and optical encoding have been reported to identify those libraries. In this paper, a simple and efficient surface-enhanced Raman spectroscopic (SERS) barcoding method using highly sensitive SERS nanoparticles (SERS ID) is presented. The 44 kinds of SERS IDs were able to generate simple codes and could possibly generate more than one million kinds of codes by incorporating combinations of different SERS IDs. The barcoding method exhibited high stability and reliability under bioassay conditions. The SERS ID encoding based screening platform can identify the peptide ligand on the bead and also quantify its binding affinity for specific protein. We believe that our SERS barcoding technology is a promising method in the screening of one-bead-one-compound (OBOC) libraries for drug discovery. [ABSTRACT FROM AUTHOR]