Exploring the advanced techniques for protein detection facilitates cell fate investigation. However, it remains challenging to quantify and visualize the protein with one single probe. Here, a luminescent approach to detect hepatic cell fate marker albumin in vitro and living cell labeling with upconversion nanoparticles (UCNPs), which are conjugated with antibody (Ab) and rose bengal hexanoic acid (RBHA) is reported. To guarantee the detection quality and accuracy, an “OFF–ON” strategy is adopted: in the presence of albumin, the luminescence of nanoparticles remains suppressed owing to energy transfer to the quencher. Upon albumin binding to the antibody, the luminescence is recovered under near‐infrared light. In various bio‐samples, the UCNPs‐Ab‐RBHA (UCAR) nanoprobe can sense albumin with a broad detection range (5–315 ng mL⁻¹). When applied to liver ductal organoid culture medium, the UCAR can monitor hepatocyte differentiation in real time by sensing the secreted albumin. Further, UCAR enables live imaging of cellular albumin in cells, organoids, and tissues. In a CCl₄‐induced liver injury model, UCAR detects reduced albumin in liver tissue and serum. Thus, a biocompatible nanoprobe for both quantification and imaging of protein in complex biological environment with superior stability and high sensitivity is provided.

An efficient surface enhanced Raman scattering (SERS) substrate of graphene-isolated Ag nanoparticle (G/AgNP) has been developed by using excimer laser to ablate the ordered pyrolytic graphite in high vacuum onto Ag nanoparticles. By combining the electromagnetic activity of AgNPs and unique physical/chemical properties of graphene, the G/AgNP substrates shows high performance in terms of sensitivity, signal-to-noise ratio and reproducibility. The average enhancement factor obtained from the G/AgNP substrates for rhodamine 6G probe molecules is over 10⁸. The maximum deviations of SERS intensities from 20 positions of a same SERS substrate are in the range of 4.20% to 6.75% and from 20 different substrates in various batches are in the range of 4.43% to 7.71%, depending on different vibration modes. As a practical application of this SERS system, we detect the adenosine concentration in human serum. The detection results show a good linear correlation between SERS intensity and adenosine concentration within the range of 2 to 200 nM. This work may open up new opportunities in developing the applications of SERS in biomedical diagnostics, biological sensing and other biotechnology.

In the present work, a thermal treatment technique is applied for the synthesis of Ce_xSn_1−xO₂ nanoparticles. Using this method has developed understanding of how lower and higher precursor values affect the morphology, structure, and optical properties of Ce_xSn_1−xO₂ nanoparticles. Ce_xSn_1−xO₂ nanoparticle synthesis involves a reaction between cerium and tin sources, namely, cerium nitrate hexahydrate and tin (II) chloride dihydrate, respectively, and the capping agent, polyvinylpyrrolidone (PVP). The findings indicate that lower x values yield smaller particle size with a higher energy band gap, while higher x values yield a larger particle size with a smaller energy band gap. Thus, products with lower x values may be suitable for antibacterial activity applications as smaller particles can diffuse through the cell wall faster, while products with higher x values may be suitable for solar cell energy applications as more electrons can be generated at larger particle sizes. The synthesized samples were profiled via a number of methods, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). As revealed by the XRD pattern analysis, the Ce_xSn_1−xO₂ nanoparticles formed after calcination reflect the cubic fluorite structure and cassiterite-type tetragonal structure of Ce_xSn_1−xO₂ nanoparticles. Meanwhile, using FT-IR analysis, Ce-O and Sn-O were confirmed as the primary bonds of ready Ce_xSn_1−xO₂ nanoparticle samples, whilst TEM analysis highlighted that the average particle size was in the range 6−21 nm as the precursor concentration (Ce(NO₃)₃·6H₂O) increased from 0.00 to 1.00. Moreover, the diffuse UV-visible reflectance spectra used to determine the optical band gap based on the Kubelka–Munk equation showed that an increase in x value has caused a decrease in the energy band gap and vice versa.

Graphene has attracted much attention in biosensing applications due to its unique properties. In this paper, the monolayer graphene was grown by chemical vapor deposition (CVD) method. Using the graphene as the electric channel, we have fabricated a graphene field-effect transistor (G-FET) biosensor that can be used for label-free detection of RNA. Compared with conventional method, the G-FET RNA biosensor can be run in low cost, be time-saving, and be miniaturized for RNA measurement. The sensors show high performance and achieve the RNA detection sensitivity as low as 0.1 fM, which is two orders of magnitude lower than the previously reports. Moreover, the G-FET biosensor can readily distinguish target RNA from noncomplementary RNA, showing high selectivity for RNA detection. The developed G-FET RNA biosensor with high sensitivity, fast analysis speed, and simple operation may provide a new feasible direction for RNA research and biosensing.