Stem-loop DNA-assisted Silicon Nanowires-based Biochemical Sensors For Chemical And Biological Applications

Silicon nanomaterials have raised extensive attentions due to a number of traits.Among them, silicon nanowires (SiNWs) have been widely explored for a veriaty ofelectronic and biological applications. SiNWs-based bioapplications are of particularinterest, including our recent success in designing SiNWs-based nanoprobes andnanoagents for tumor detection and treatment. In particular, photostable SiNWs-basednanoprobes have been employed for bioimaging application in a long-term manner.SiNWs-based near-infrared (NIR) hyperthermia agents featuring significantphoto-thermal effects can efficiently kill malignant tumor cells. Very recently, takingadvantage of huge surface-to-volume ratio and porous structure, we further developed aclass of SiNWs-based drug nanocarriers capable of cancer treatment in vitro and in vivo.By utilizing high quenching efficiency (QE,>90%), large surface-to-volume ratio, andfacile surface tailorability of SiNWs, in this paper, we employ stem-loop DNA andSiNWs for fabricating a novel type of SiNWs-based fluorescent sensors featuring highsensitivity, specificity, and multiplexing capabilities for chemical and biologicalapplicationsIn principle, fluorescent signals can effectively switch between “on” and “off” statevia adjusting distance between SiNWs and fluorescein tagged with DNA. As a result,the sensor enables rapid and sensitive detection of DNA targets with a concentration aslow as1pM, based on disruption or formation of stem-loop configuration in thepresence of targets. Moreover, the huge planar surface of SiNWs facilitatessimultaneous assembly with different DNA strands, which is favorable for multiplexedDNA detection. On the other hand, the SiNWs-based sensor is highly efficacious fordetecting heavy metal ions. Mercury ions (Hg2+) of low concentrations (e.g.,5pM) arereadily identified from its mixture with over10kinds of interfering metal ions, even inreal water samples. Given that SiNWs can be fabricated in facile, reproducible and low-cost manners, this kind of SiNWs-based high-performance sensor is expected to bepractical analytical tools for a variety of biological and environment-protectionapplications.