Super-Long SERS Active Single Silver Nanowires for Molecular Imaging in 2D and 3D Cell Culture Models.

Establishing a systematic molecular information analysis strategy for cell culture models is of great significance for drug development and tissue engineering technologies. Here, we fabricated single silver nanowires with high surface-enhanced Raman scattering activity to extract SERS spectra in situ from two-dimensional (2D) and three-dimensional (3D) cell culture models. The silver nanowires were super long, flexible and thin enough to penetrate through multiple cells. A single silver nanowire was used in combination with a four-dimensional microcontroller as a cell endoscope for spectrally analyzing the components in cell culture models. Then, we adopted a machine learning algorithm to analyze the obtained spectra. Our results show that the abundance of proteins differs significantly between the 2D and 3D models, and that nucleic acid-rich and protein-rich regions can be distinguished with satisfactory accuracy.

Injectable Magnesium-Zinc Alloy Containing Hydrogel Complex for Bone Regeneration.

Gelatin methacryloyl (GelMA) has been widely used in bone engineering. It can also be filled into the calvarial defects with irregular shape. However, lack of osteoinductive capacity limits its potential as a candidate repair material for calvarial defects. In this study, we developed an injectable magnesium-zinc alloy containing hydrogel complex (Mg-IHC), in which the alloy was fabricated in an atomization process and had small sphere, regular shape, and good fluidity. Mg-IHC can be injected and plastically shaped. After cross-linking, it contents the elastic modulus similar to GelMA, and has inner holes suitable for nutrient transportation. Furthermore, Mg-IHC showed promising biocompatibility according to our evaluations of its cell adhesion, growth status, and proliferating activity. The results of alkaline phosphatase (ALP) activity, ALP staining, alizarin red staining, and real-time polymerase chain reaction (PCR) further indicated that Mg-IHC could significantly promote the osteogenic differentiation of MC3T3-E1 cells and upregulate the genetic expression of collagen I (COL-I), osteocalcin (OCN), and runt-related transcription factor 2 (RUNX2). Finally, after applied to a mouse model of critical-sized calvarial defect, Mg-IHC remarkably enhanced bone formation at the defect site. All of these results suggest that Mg-IHC can promote bone regeneration and can be potentially considered as a candidate for calvarial defect repairing.

An improved gel-based DNA microarray method for detecting single nucleotide mismatch.

3-D polyacrylamide gel-based DNA microarray platforms provide a high capacity for nucleic acids immobilization and a solution-mimicking environment for hybridization. However, several technological bottlenecks still remain in these platforms, such as difficult microarray preparation and high fluorescent background, which limit their application. In this study, two new approaches have been developed to improve the convenience in microarray preparation and to reduce the background after hybridization. To control the polymerization process, solutions containing acrylamide-modified oligonucleotide, acrylamide, glycerol and ammonium persulfate are spotted onto a functionalized glass slide, and then the slide is transferred to a vacuum chamber with TEMED, so that TEMED is vaporized and diffused into the spots to induce polymerization. By applying an electric field across a hybridized microarray to remove the nonspecifically bound labeled targets, this approach can solve the problem of high fluorescent background of the gel-based microarray after hybridization. Experimental results show that our immobilization method can be used to construct high quality microarrays and exhibits good reproducibility. Moreover, the polymerization is not affected by PCR medium, so that PCR products can be used for microarray construction without being treated by commercial purification cartridges. Electrophoresis can improve the signal-to-noise significantly and has the ability to differentiate single nucleotide variation between two homozygotes and a heterozygote. Our results demonstrated that this is a reliable novel method for high-throughput mutation analysis and disease diagnosis.