An Origami Paper-Based Analytical Device for Rapid and Sensitive Analysis of Acrylamide in Foods

Rapid and sensitive detection of acrylamide in food samples is important for food safety and public health. Here, we describe a disposable origami paper-based analytical device (denoted doPAD) for colorimetric detection of acrylamide. This device uniquely exploits 3D origami folding paper for spatial control of the target recognition and signal readout, thus resulting in a positive correlation between the signals and the analytes. Under optimal conditions, the device achieved the quantitative analysis of acrylamide with a limit of detection of 1.13 μg/L within 120 min (including a derivatization time of 90 min and an assay time of 21 min). Furthermore, our method allowed the rapid and sensitive detection of acrylamide in complex food matrices. We envision that the platform described will find useful applications in the fields of food safety and environmental health.

A Study on the Performance of a Silicon Photodiode Sensor for a Particle Dosimeter and Spectrometer

A lunar vehicle radiation dosimeter (LVRAD) has been proposed for studying the radiation environment on the lunar surface and evaluating its impact on human health. The LVRAD payload comprises four systems: a particle dosimeter and spectrometer (PDS), a tissue-equivalent dosimeter, a fast neutron spectrometer, and an epithermal neutron spectrometer. A silicon photodiode sensor with compact readout electronics was proposed for the PDS. The PDS system aims to measure protons with 10–100 MeV of energy and assess dose in the lunar space environment. The manufactured silicon photodiode sensor has an effective area of 20 mm × 20 mm and thickness of 650 μm; the electronics consist of an amplifier, analog pulse processor, and a 12-bit analog-to-digital converter for signal readout. We studied the responses of silicon sensors which were manufactured with self-made electronics to gamma rays with a wide range of energies and proton beams.

OptoAssay - Light-controlled Dynamic Bioassay Using Optogenetic Switches

Circumventing the limitations of current bioassays, we introduce the first light-controlled assay, the OptoAssay, towards wash- and pump-free point-of-care diagnostics. Extending the capabilities of standard bioassays with light-dependent and reversible interaction of optogenetic switches, OptoAssays enable a bi-directional movement of assay components, only by changing the wavelength of light. Combined with smartphones, OptoAssays obviate the need for external flow control systems like pumps or valves and signal readout devices.

Species-specific quantification of circulating ebolavirus burden using VP40-derived peptide variants

Six ebolavirus species are reported to date, including human pathogens Bundibugyo virus (BDBV), Ebola virus (EBOV), Sudan virus (SUDV), and Taï Forest virus (TAFV); non-human pathogen Reston virus (RESTV); and the plausible Bombali virus (BOMV). Since there are differences in the disease severity caused by different species, species identification and viral burden quantification are critical for treating infected patients timely and effectively. Here we developed an immunoprecipitation-coupled mass spectrometry (IP-MS) assay for VP40 antigen detection and quantification. We carefully selected two regions of VP40, designated as peptide 8 and peptide12 from the protein sequence that showed minor variations among Ebolavirus species through MS analysis of tryptic peptides and antigenicity prediction based on available bioinformatic tools, and generated high-quality capture antibodies pan-specific for these variant peptides. We applied this assay to human plasma spiked with recombinant VP40 protein from EBOV, SUDV, and BDBV and virus-like particles (VLP), as well as EBOV infected NHP plasma. Sequence substitutions between EBOV and SUDV, the two species with highest lethality, produced affinity variations of 2.6-fold for p8 and 19-fold for p12. The proposed IP-MS assay differentiates four of the six known EBV species in one assay, through a combination of p8 and p12 data. The IP-MS assay limit of detection (LOD) using multiple reaction monitoring (MRM) as signal readout was determined to be 28 ng/mL and 7 ng/mL for EBOV and SUDV respectively, equivalent to ~1.625–6.5×105 Geq/mL, and comparable to the LOD of lateral flow immunoassays currently used for Ebola surveillance. The two peptides of the IP-MS assay were also identified by their tandem MS spectra using a miniature MALDI-TOF MS instrument, greatly increasing the feasibility of high specificity assay in a decentralized laboratory.

Development of detector pixels based on silicon photomultipliers for the Cherenkov gamma-ray telescope TAIGA-IACT

The design and scheme of signal readout from silicon photomultipliers OnSemi MicroFJ-60035 used as sensitive elements (pixels) of a new detector cluster for the camera of the Cherenkov gamma-ray telescope TAIGA-IACT are developed. The design of the developed pixel follows the shape of the photomultiplier tube XP1911 using in the first generation clusters, and that provides compatibility of the new cluster with the telescope camera. Due to the adjustable gain, the developed scheme allows one to detect and digitize signals in a wide dynamic range from several to 10 000 photons.