Recently, much attention has been paid to tissue engineering and local gene delivery system in periodontal tissue regeneration. Gene-activated matrix (GAM) blends these two strategies, serving as a local bioreactor with therapeutic gene expression and providing a structural template to fill the lesion defects for cell adhesion, proliferation and synthesis of extracellular matrix (ECM). In this study, we designed a novel GAM with embedded chitosan/plasmid nanoparticles encoding platelet derived growth factor (PDGF) based on porous chitosan/collagen composite scaffold. The chitosan/collagen scaffold acted as three-dimensional carrier and chitosan nanoparticles condensed plasmid DNA. The plasmid DNA entrapped in the scaffolds showed a sustained and steady release over 6 weeks and could be effectively protected by chitosan nanoparticles. MTT assay demonstrated that periodontal ligament cells (PDLCs) cultured into the novel GAM achieved high proliferation. Luciferase reporter gene assay displayed that the novel GAM could express 1.07 x 10(4) LU/mg protein after 1 week and 8.97 x 10(3) LU/mg protein after 2 weeks. The histological results confirmed that PDLCs maintained a fibroblast figure and the periodontal connective tissue-like structure formed in the scaffolds after 2 weeks. Semi-quantitative immunohistochemical results suggested that PDGF protein expressed at a relatively high level after 2 weeks. From this study, it can be concluded that the novel GAM had potential in the application of periodontal tissue engineering.

We present a simple, rapid, and effe/ctive colorimetric sensor array (or colorimetric electronic tongue) for discrimination of antioxidants, which is based on the oxidation etching of triangular silver nanoparticles (TriAgNPs) by three metal ions (Se 2+ , Sn 4+ , and Ni 2+ ) as array's recognition elements and the inhibition of TriAgNP etching by antioxidants. Since highly reactive edges/tips of TriAgNPs are easier to be etched than other regions, the morphology of TriAgNPs undergoes a transition from nanoprism to nanodisk, accompanied by a color change from blue to yellow. The addition of diverse antioxidants inhibits TriAgNP etching in varying degrees, forming different etching morphologies with rainbowlike color. Surface plasmon resonance peak shift (Δλ) values of final TriAgNPs were captured as colorimetric signal outputs for further data processes. Linear discriminant analysis, hierarchical clustering analysis, heat map, etc. were adopted in the further data analysis process, showing the excellent discrimination ability of the sensor array for six antioxidants at 1 nM level. Moreover, selectivity experiments and practical application tests show that our sensor array had considerable selectivity and great potential in real samples.

Sensor arrays, called “electronic tongues”, provide an alternative to time-consuming detection approaches. In this work, a colorimetric-sensor array composed of three recognition receptors (cysteine, l-glutathione, and melamine) was developed for fast discrimination of toxic metal ions. Different recognition receptors exhibited different binding affinities toward metal ions, causing diverse gold-nanoparticle (AuNP)-aggregation behaviors and generating distinct colorimetric response patterns. As “fingerprints”, these response patterns can be quantitatively analyzed by linear-discriminant analysis (LDA). The sensor array achieved good discrimination of six kinds of metal ions (Ti4+, Cr3+, Mn2+, Fe3+, Pb2+, and Sn4+) in deionized water and real samples. It possessed good reproducibility and exhibited a linear range of 100–900 nM (R 2 = 0.97) for Ti4+, 100–900 nM (R 2 = 0.97) for Cr3+, 100–900 nM (R 2 = 0.98) for Mn2+, 100–1000 nM (R 2 = 0.92) for Sn4+, 100–800 nM (R 2 = 0.94) for Fe3+, and 100–900 nM (R 2 = 0.97) for Pb2+. The sensor array shows feasible potential in environmental monitoring and simplification of water-quality analysis.

Flavonoids are closely related to human health, and the distinguishiment of flavonoids is an important but difficult issue. We herein unveil a novel colorimetric sensor array for the rapid identification of 7 flavonoids (e.g., gallocatechin (GC), morin hydrate (MH), puerarin (Pu), epigallocatechin gallate (EGCG), catechin (C), rac Naringenin (rN), and Flavone (Fla)) for the first time. The colorimetric performances of gold nanoparticles (AuNPs) are characteristically correlated with thiocholine, which is issued from the enzymatic hydrolysis of acetylcholine (AcCh). Therefore, as a proof-of-concept design, three sensors (Cu2+/acetylcholinesterase (AcChE)/AcCh/AuNPs, Zn2+/AcChE/AcCh/AuNPs, and Mn2+/AcChE/AcCh/AuNPs) were constructed to form our sensor array. The distinct affinities between flavonoids and metal ions would cause varying degrees of effective reactivation of AcChE, leading to unique colorimetric response patterns upon being challenged with the seven flavonoids for their pattern recognition, enabling an excellent identification of the seven flavonoids at a concentration of 20 nM and different concentrations of individual flavonoids, as well as mixtures of them.

The detection and discrimination of biothiols is of cardinal significance because of their key roles in biological systems and numerous diseases. The present work has developed a simple but effective colorimetric sensor array for identification of biothiols. The sensor array is based on utilization of triple-channel properties (the red (R), green (G), and blue (B) alterations) of polydopamine (PDA)-functionalized gold nanoparticles (AuNPs). Five metal ions (Fe3+, Mg2+, Ca2+, Ag+, and Hg2+) as sensing elements are anchored on the surface of PDA–AuNPs through chelating reaction between metal ions and PDA. Different thiols show distinct binding affinities toward these metal ions, generating diverse colorimetric response patterns (i.e., RGB variations) as “fingerprints” related to each specific biothiol, which can be quantitatively differentiated by linear discriminant analysis (LDA) and hierarchical clustering analysis (HCA). The sensor array can well discriminate six biothiols (dithiothreitol, l-cysteine, glutathione, mercaptoethanol, mercaptosuccinic acid, and mercaptoacetic acid) with 100% accuracy and high sensitivity at the 30 nM level. The sensing strategy, with simple preparation, fast response, excellent sensitivity, and especially stable and high-throughput signal output, is promising for practical applications in artificial olfactory systems.