Multiplexed DNA target detection is of great significance in many fields including clinical diagnostics, environmental monitoring, biothreat detection and forensics. Although the emergence of DNA chip technology has accelerated this process, it is still a challenge to perform ultrasensitive DNA assay at low attomol concentrations so that DNA detection can be directly achieved without a PCR protocol. In this work, an oligonucleotide-functionalized silver nanoparticle tag has been successfully developed for multiplexed DNA electrochemical detection with ultrahigh sensitivity. The multiprobes containing oligo(d)A and the reporting probes were anchored onto the silver nanoparticles, followed by hybridizing with the silver nanoparticle conjugate modified with oligo(d)T. The hybridization-induced tag was found to show an aggregated nanostructure 10 times larger than the individual nanoparticle, as revealed by TEM. For sandwich-based assays, the tag was specifically coupled to a gold electrode surface via target DNA. Compared to a single nanoparticle label, this novel tag has shown excellent electroactive property and produces 10(3)-fold amplification in the differential pulse voltammetric (DPV) method. Hepatitis B virus (HBV) sequence was employed as a sample model, and we have achieved a detection limit of 5 aM ( approximately 120 molecules in 40 muL volume), demonstrating ultrasensitive measurement for DNA. The property of the electrochemical process involving silver aggregates was further investigated and the integrative oxidation of the silver tag was observed. We further demonstrated the multiplexed DNA target detection using array chips functionalized with Herpes simplex virus (HSV), Epstein-Barr virus (EBV) and cytomegalovirus (CMV) sequences, which shows effective recognition of the relative sequences individually or simultaneously. The method offers a uniquely new approach for DNA detection with ultrahigh sensitivity as well as advantages of rapidity, throughput, and miniaturization.

Co-assembly of a cell adhesive peptide conjugate and alginate affords multifunctional composite hydrogels for rapid hemostasis and efficacious wound healing.

Infected wounds caused by persistent inflammation exhibit poor vascularization and cellular infiltration. In order to rapidly control the inflammatory effect and accelerate wound healing, it is necessary to develop a novel drug vehicle addressing the need for infected wounds. Herein, we developed a novel dual-drug delivery system with micrometer-scale alginate fibers encapsulated in instant self-assembly peptide hydrogel. Short peptides with the sequence of Nap-Gly-Phe-Phe-Lys-His (Nap-GFFKH) could self-assemble outside the microfluidic-based alginate microfibers in weak acidic solution (pH ≈ 6.0) within 5 s. The gelation condition is close to the pH environment of the human skin. We further constructed recombinant bovine basic fibroblast growth factor (FGF-2) in fibrous alginate, which was encapsulated in antibiotic-loaded peptide hydrogel. The dual-drug delivery system exhibited good mechanical property and sustained release profiles, where antibiotic could be rapidly released from the peptide hydrogel, while the growth factor could be gradually released within 7 days. Both in vitro antibacterial experiments and in vivo animal experiments confirmed that such a dual-drug delivery system has good antibacterial activity and enhances wound healing property. We suggested that the dual-drug delivery system could be potentially applied for controlled drug release in infected wound healing, drug combination for melanoma therapy, and tissue engineering.

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