Analysis & sensing最新文献

Surface enhanced Raman scattering (SERS) is difficult to detect molecules with weak adsorption, like aldehydes. Herein, we fabricated core-shell Au@Ag-MOFs nanoparticles as SERS substrate. The shell can be controllably synthesized, with the thickness about 3 nm. After the morphology and SERS activity characterization, Au@Ag-MOFs were employed to sensitive and label-free detect p-chlorobenzaldehyde (PCB) in water samples. The pore structure and large surface area of Ag-MOFs shell results more adsorption of PCB, dragging more molecules to “hot spots” area. The abundant amino group in Ag-MOFs allows the occurrence of Schiff base reaction with aldehyde group in PCB. Taking the synergistic effect of both physical and chemical enhancement, SERS signals of PCB were greatly boosted. The method showed good linearity between 5.0×10⁻¹² M to 1.0×10⁻⁸ M for PCB with the limit of detection (LOD) down to 3.3×10⁻¹² M. The proposed method has great potential to be a reliable analytical strategy for aldehydes in real samples.

Mass spectrometry imaging (MSI) is an invaluable tool for the spatial visualization of molecules in vivo. However, the question of whether observed annotations are endogenous or artificial (i. e., from in-source fragmentation) is critical and has been largely unexplored in multimodal MSI. In matrix-assisted laser desorption/ionization (MALDI)-MSI datasets from researchers worldwide, PAs were found to represent up to 18 % of annotations in rat brain. Rat brain was additionally imaged here using nanospray desorption electrospray ionization (nano-DESI), a softer ionization strategy. No PAs observed with MALDI were present in the nano-DESI dataset. Further investigation strongly indicated lipid fragmentation to PAs for MALDI-MSI, but not with nano-DESI-MSI. We finally extend this observation to the MALDI-MSI analyses of human tissues, showing that PA annotations comprised up to 16 % of annotations. Therefore, this study shows that MSI annotations should be carefully interrogated, as in-source fragmentation or modification of lipids may contribute substantially to false annotations and incorrect biological interpretations.

Current screening methods for diabetic kidney disease (DKD), characterized by albumin excretion in urine, are expensive or only identify patients in late disease stages. Hence, there is need for a cost-effective, quick, and portable screening tool which identifies patients at DKD onset. Here we report that ultracentrifugation coupled with infrared spectroscopy and machine learning can identify and quantify low level microalbuminuria in urine samples from a cohort of diabetic patients (n=155) and controls (n=22). Independent testing of the methods indicated that classification analysis discriminated between normo- and micro/macroalbuminuric samples with sensitivity of >91 % and specificity of >99 %. Regression methods quantified albumin concentration in the samples with error values of 17 and 44 mg/L for normo- and microalbuminuric patients. Using only 700 μL of sample, this approach identifies patients at an earlier stage of disease than a urinary dipstick, whilst also yielding results cheaper and faster than the albumin to creatinine ratio.

Invited for this month‘s cover are the collaborating group(s) of Center for Biospectroscopy at Monash University and Austin Health at the University of Melbourne, University of Eastern Finland and the University of Queensland. The cover-art shows a handheld near-infrared spectroscopic probe to detect fibrosis in real time using a murine model. More information can be found in the Research Article by John A. Adegoke, Jaishankar Raman, Bayden R. Wood, and co-workers.

Lipids are small but complex biomolecules that feature an immense structural and functional diversity. The molecular structure and biological functions of lipids are intricately linked. Therefore, modern lipid analysis strives for complete structural elucidation and spatial mapping of individual species in tissues. Mass spectrometry is the uncontested key technology in lipidomics but cannot achieve this goal as a standalone technique. In particular, the distinction between frequently occurring isomers constitutes a major challenge. A promising step towards complete structural analysis of lipids consists in the coupling of mass spectrometry with laser light. Here we review recent advances in lipidomics applications employing laser-induced ultraviolet and infrared photodissociation and ion spectroscopy, which substantially increase the gain in structural information. Fundamental concepts, instrumentation and promises of these powerful emerging techniques for future lipid analysis are outlined.

The cover picture shows a handheld near-infrared spectroscopic probe to detect fibrosis in real time using a murine model. The major differences between spectra of healthy and fibrotic tissue were seen in specific absorption bands, which were attributed to disruption in the collagen network. More information can be found in the Research Article by John A. Adegoke, Jaishankar Raman, Bayden R. Wood, and co-workers.

Quenching singlet oxygen is the key to improve photostability of fluorescent dyes. We have systematically studied the capability of a new singlet oxygen quencher, DABCOnium (an alkylated derivative of 1,4-diazabicyclo[2.2.2] octane) on removing singlet oxygen. Results showed that DABCOnium can significantly enhancing photostability of fluorescent thin films for more than 4.3 times compared with that without DABCOnium. After 2 hours of continuous irradiation, fluorescent film doped with DABCOnium retained 90 % of its original fluorescence intensity, which paves a new way in designing high performance singlet oxygen quenchers.

The probe-target interactions in the interfaces are significantly critical to biosensing. However, the disordered arrangement of probes and nonspecific adsorption of proteins in the biosensing interfaces for conventional biosensors often restricted the accessibility and recognition efficiency of probes towards targets, leading to poor detection performances (e. g., sensitivity and selectivity). Engineering of biosensing interfaces with functional molecules or nanomaterials has provided a promising molecular toolkit for enhanced accessibility and efficient recognition of biosensing probes. Among them, DNA has been an appealing material for interface engineering, because of its unique merits of biocompatible, predictable hybridization, and unparallel self-assembly ability. In particular, employing tetrahedra DNA nanostructures (TDNs) to engineer interfaces has been a powerful means to improve biosensor performance. Here, this review introduces the recent progress in TDN-based interface engineering. Then, we summarize the roles of TDNs in tailoring the properties of different interfaces, including electrode surface, channel surface, cell surface, etc., and highlight their biosensing applications. Finally, scientific challenges and future perspectives of TDN-engineered biosensing interface are also discussed.

The cover feature image illustrates a newly reported biosensor intended to reliably monitor patient use and compliance of benzodiazepines. Akin to the epidemic rise in use and abuse of this drug class, the artist has placed the biosensor literally under the magnifying glass hoping to draw attention to an improved and unique DNA aptamer-based detection method for testing patient urine. The cover art was designed by Marc Polaske and was inspired by noir detective graphic novels. More information can be found in the Research Article by John S. Samuelian and Dana A. Baum.

RNA imaging paves the way to investigate RNA function and regulation from the aspect of RNA subcellular localization and expression level. In the past decades, various highly precise and genetic coding fluorescent RNA, which can bind and light up the fluorophore by their specific sequence/structure, has been developed for RNA imaging, including Broccoli, Mango, SRB-2, RhoBAST, and Pepper et al. In this Review, we summarize the RNA imaging approaches and the progress made in the development of fluorescent RNA. Next, we emphasize the application of fluorescent RNA for in situ RNA imaging in living cells. Of particular note, besides the artificially selected fluorescent RNAs, a new kind of fluorophore that can bind and light up intrinsic RNA structure is described together for the first time. Finally, a summary of current strategies for designing fluorescent RNA and future perspectives are also presented. We hope this expanding topic will inspire the study of the architecture and functions of these fascinating molecular machinery in biological systems.