Herein, we present a multifunctional chip based on surface-enhanced Raman scattering (SERS) that effectively captures, discriminates, and inactivates pathogenic bacteria. The developed SERS chip is made of a silicon wafer decorated with silver nanoparticles and modified with 4-mercaptophenylboronic acid (4-MPBA). It was prepared in a straightforward manner by chemical reduction assisted by hydrogen fluoride etching, followed by the conjugation of 4-MPBA through AgS bonds. The dominant merits of the fabricated SERS chip include excellent reproducibility with a relative standard deviation (RSD) value smaller than 11.0 %, adaptable bacterial-capture efficiency (ca. 60 %) at low concentrations (500-2000 CFU mL(-1) ), a low detection limit (down to a concentration of 1.0×10(2)  cells mL(-1) ), and high antibacterial activity (an antibacterial rate of ca. 97 %). The SERS chip enabled sensitive and specific discrimination of Escherichia coli and Staphylococcus aureus from human blood.

Simultaneous imaging and treatment of infections remains a major challenge, with most current approaches being effective against only one specific group of bacteria or not being useful for diagnosis. Here we develop multifunctional nanoagents that can potentially be used for imaging and treatment of infections caused by diverse bacterial pathogens. The nanoagents are made of fluorescent silicon nanoparticles (SiNPs) functionalized with a glucose polymer (e.g., poly[4-O-(α-D-glucopyranosyl)-D-glucopyranose]) and loaded with chlorin e6 (Ce6). They are rapidly internalized into Gram-negative and Gram-positive bacteria by a mechanism dependent on an ATP-binding cassette (ABC) transporter pathway. The nanoagents can be used for imaging bacteria by tracking the green fluorescence of SiNPs and the red fluorescence of Ce6, allowing in vivo detection of as few as 10 5 colony-forming units. The nanoagents exhibit in vivo photodynamic antibacterial efficiencies of 98% against Staphylococcus aureus and 96% against Pseudomonas aeruginosa under 660 nm irradiation.

There is an increasing interest in the development of surface-enhanced Raman scattering (SERS) sensors for rapid and accurate on-site detection of hidden explosives. However, portable SERS methods for trace explosive detection in real systems remain scarce, mainly due to their relatively poor reliability and portability. Herein, we present the first demonstration of a portable silicon-based SERS analytical platform for signal-on detection of trace trinitrotoluene (TNT) explosives, which is made of silver nanoparticle (AgNP)-decorated silicon wafer chip (0.5 cm × 0.5 cm). In principle, under 514 nm excitation, the Raman signals of p-aminobenzenethiol (PABT) modified on the AgNP surface could be largely lit up due to the formation of electronic resonance-active TNT-PABT complex. In addition, the surface of AgNPs and silicon substrate-induced plasmon resonances also contribute the total SERS enhancement. For quantitative evaluation, the as-prepared chip features ultrahigh sensitivity [limit of detection is down to ∼1 pM (∼45.4 fg/cm)] and adaptable reproducibility (relative standard deviation is less than 15%) in the detection of TNT standard solutions. More importantly, the developed chip can couple well with a hand-held Raman spectroscopic device using 785 nm excitation, suitable for qualitative analysis of trace TNT even at ∼10 M level from environmental samples including lake water, soil, envelope, and liquor with a short data acquisition time (∼1 min). Furthermore, TNT vapors diffusing from TNT residues (∼10 M) can be detected by using such a portable device, indicating its feasibility in determination of hidden samples.

Herein, we present the first example of a silicon nanoshuttle-based security ink simultaneously featuring attractive optical and magnetic properties, suitable for fluorescent and magnetic anti-counterfeiting and encryption. Significantly, the information can be dual-encrypted through multi-color fluorescence and longitudinal (T)/transverse (T) relaxation contrast by using the silicon nanoshuttle-based security ink. We further demonstrate the feasibility of this high-performance ink for practical application in banknote anti-counterfeiting.