In Situ Detection of Hydrogen Sulfide in 3D-Cultured, Live Prostate Cancer Cells Using a Paper-Integrated Analytical Device

In this study, a paper-integrated analytical device that combined a paper-based colorimetric assay with a paper-based cell culture platform was developed for the in situ detection of hydrogen sulfide (H2S) in three-dimensional (3D)-cultured, live prostate cancer cells. Two kinds of paper substrates were fabricated using a simple wax-printing methodology to form the cell culture and detection zones, respectively. LNCaP cells were seeded directly on the paper substrate and grown in the paper-integrated analytical device. The cell viability and H2S production of LNCaP cells were assessed using a simple water-soluble tetrazolium salt colorimetric assay and H2S-sensing paper, respectively. The H2S-sensing paper showed good sensitivity (sensitivity: 6.12 blue channel intensity/μM H2S, R2 = 0.994) and a limit of quantification of 1.08 μM. As a result, we successfully measured changes in endogenous H2S production in 3D-cultured, live LNCaP cells within the paper-integrated analytical device while varying the duration of incubation and substrate concentration (L-cysteine). This paper-integrated analytical device can provide a simple and effective method to investigate H2S signaling pathways and drug screening in a 3D culture model.

Intracellular bound chlorophyll residues identify 1 Gyr-old fossils as eukaryotic algae

The acquisition of photosynthesis is a fundamental step in the evolution of eukaryotes. However, few phototrophic organisms are unambiguously recognized in the Precambrian record. The in situ detection of metabolic byproducts in individual microfossils is the key for the direct identification of their metabolisms. Here, we report a new integrative methodology using synchrotron-based X-ray fluorescence and absorption. We evidence bound nickel-geoporphyrins moieties in low-grade metamorphic rocks, preserved in situ within cells of a ~1 Gyr-old multicellular eukaryote, Arctacellularia tetragonala. We identify these moieties as chlorophyll derivatives, indicating that A. tetragonala was a phototrophic eukaryote, one of the first unambiguous algae. This new approach, applicable to overmature rocks, creates a strong new proxy to understand the evolution of phototrophy and diversification of early ecosystems.

Flexible SERS substrate of silver nanoparticles on cotton swabs for rapid in-situ detection of melamine

It is important to be able to detect melamine via a sensitive and fast method in the field of food safety. Surface-enhanced Raman scattering (SERS) has attracted much attention due...

HuluFISH non-denaturing in situ detection of genomic DNA opened by CRISPR-Cas9 Nickase and Exonuclease

DNA fluorescence in situ hybridization (FISH) has been widely used in diagnosis and genetic research. Traditional Bacterial artificial chromosome (BAC) or oligonucleotide based probe to detect DNA in situ is only effective when the target is relatively large, usually over 150Kb DNA fragments. And it involves heat denaturation steps to open the DNA for in situ hybridization. The heat process can affect the fine structure of nuclei. Here we reported a novel method based on Cas9 nickase and exonuclease digestion of double strand DNA and permanently mark the DNA in single strand state for FISH. With this novel design, we detected non-repetitive genomic loci as small as 2Kb.