Online Quantitative Analysis of Chlorine Contents in Chlorinated Paraffins by Facile Raman Spectroscopy.

Online analysis of industrial chemicals is extremely important for managing product quality and performance. The chlorine (Cl) content is one of the most important technical metrics for chlorinated paraffins (CPs), and the conventional approaches to estimate Cl contents require transforming the Cl element to chloride followed by quantitative analysis with either titration or instrumentation, which are normally tedious and time-consuming and cannot simultaneously guide the industrial production. Here, we developed a rapid, real-time, and online approach to determine the Cl content of CPs with facile Raman spectroscopy. The chlorination of paraffins generated two new Raman peaks at 610-618 and 668-690 cm-1, which are associated with the vibrational modes of the SHH and SHC conformations of the C-Cl bond in CPs, respectively. More importantly, the corresponding peak of the SHH conformation decreased and that of the SHC conformation increased with the enhancement of the chlorination degree of CPs. The ratiometric calculation of the two respective Raman peak areas leads to a quantitative analysis of the Cl content of CPs. The developed approach can online provide the Cl contents of CPs within seconds accurately but without the tedious sample treatment required by conventional approaches. The strategy of integrating Raman analysis with the industrial pipeline will help in managing the production and quality control of industrial chemicals.

Multifunctional silicon calcium phosphate composite scaffolds promote stem cell recruitment and bone regeneration.

A scaffold is one of the most significant implants for treating bone injury, while the precise control of stem cell proliferation and differentiation within a scaffold is still challenging. In this work, a composite scaffold was designed to be capable of recruiting endogenous stem cells, stimulating osteogenic differentiation and achieving significant bone repair function. The designed SiCP + SF@PFS silica-calcium phosphate composite scaffold was obtained by mixing the peptide PFS containing silk fibroin solution with the SiCP scaffold, and treating with horseradish peroxidase and H2O2. The results showed that the composite scaffold was able to release the PFS peptide continuously to induce the migration of mesenchymal stem cells. Meanwhile, cell proliferation and osteogenic differentiation were also improved after being seeded on the scaffold. In the cranial defect rat model, the composite scaffold was able to recruit CD29+ and CD90+ cells one week after implantation around the injury sites. The results of Micro-CT, H&E staining, Masson's staining and immunohistochemical staining indicated that the composite scaffold was able to promote new bone formation significantly.

Recent advances in 3D hydrogel culture systems for mesenchymal stem cell-based therapy and cell behavior regulation.

Mesenchymal stem cells (MSCs) have been increasingly recognized as a resource for disease treatment and regenerative medicine. Meanwhile, the unique chemical and physical properties of hydrogels provide innate advantages to achieve high quality MSCs on a large scale. Tremendous kinds of biomaterials have been employed to form hydrogels providing a controllable microenvironment for culturing MSCs. The development of materials science makes it possible to mimic the natural extracellular matrix (ECM), providing an effective means to understand mechanisms such as sensing and remodeling of the different microenvironments by MSCs. The mechanical cues, the formation mechanisms, material types and combination hydrogels are all discussed in this review for three-dimensional (3D) hydrogel culture systems. This article also focuses on the latest development of hydrogel culture systems applied both in vivo and in vitro. Besides the innovation of materials, the culture methods and spatiotemporal cues during the culture stage are other directions of exploration for 3D culture systems. The ultimate goal of hydrogel 3D culture systems is to perfectly mimic the native microenvironment for the study of MSC behavior or the applications of MSC-based therapies.