Chemical Transdifferentiation of Somatic Cells: Unleashing the Power of Small Molecules.

Chemical transdifferentiation is a technique that utilizes small molecules to directly convert one cell type into another without passing through an intermediate stem cell state. This technique offers several advantages over other methods of cell reprogramming, such as simplicity, standardization, versatility, no ethical and safety concern and patient-specific therapies. Chemical transdifferentiation has been successfully applied to various cell types across different tissues and organs, and its potential applications are rapidly expanding as scientists continue to explore new combinations of small molecules and refine the mechanisms driving cell fate conversion. These applications have opened up new possibilities for regenerative medicine, disease modeling, drug discovery and tissue engineering. However, there are still challenges and limitations that need to be overcome before chemical transdifferentiation can be translated into clinical practice. These include low efficiency and reproducibility, incomplete understanding of the molecular mechanisms, long-term stability and functionality of the transdifferentiated cells, cell-type specificity and scalability. In this review, we compared the commonly used methods for cell transdifferentiation in recent years and discussed the current progress and future perspective of the chemical transdifferentiation of somatic cells and its potential impact on biomedicine. We believe that with ongoing research and technological advancements, the future holds tremendous promise for harnessing the power of small molecules to shape the cellular landscape and revolutionize the field of biomedicine.

Removal of low-concentration tetracycline from water by a two-step process of adsorption enrichment and photocatalytic regeneration.

Developing a high-performance method that can effectively control pollution caused by low concentrations of antibiotics is urgently needed. Herein, a novel three-dimensional PPy/Zn3In2S6 nanoflower composites were prepared for the comprehensive treatment of low-concentration tetracycline (Tc) hydrochloride in wastewater based on the adsorption/photocatalysis of Zn3In2S6 and the conductivity of PPy. In this preparation method, adsorption enrichment and photocatalytic regeneration were conducted in two steps, eliminating the dilution and dispersion effects of aqueous solvents on photocatalytic species and antibiotics. Results showed that Zn3In2S6 could effectively adsorb 87.85% of Tc at pH of 4.5 and photocatalytically degrade Tc at pH of 10.5. Although the adsorption capacity of Zn3In2S6 was slightly reduced after being combined with PPy, its photocatalytic efficiency was substantially enhanced. Specifically, 0.5%PPy/Zn3In2S6 could degrade 99.92% of the surface-enriched Tc in 1 h and induce the regeneration of the adsorption sites. Furthermore, the adsorption capacity remained above 85% even after recycling PPy/Zn3In2S6 ten times. The photocatalytic degradation mechanism analysis revealed that the enrichment of Tc on 0.5%PPy/Zn3In2S6 negatively impacts the photocatalytic efficiency, while •O2- and •OH radicals were the main oxidative species that played an important role in the photoregeneration process.

Distribution characteristics and potential release risk of nitrogen in sediments in Lake Daihai, China.

Nitrogen (N) in sediments was a key element of lake eutrophication. The spatial distribution characteristics of four parts N in surface sediments were investigated by sequential extraction method, including free nitrogen (FN), exchangeable nitrogen (EN), hydrolyzable nitrogen (HN), and residual nitrogen (RN). Modified models were utilized to describe the adsorption isotherms of ammonia nitrogen (NH4+-N) in sediments and thus predict the risk of N release. The correlation between environmental factors and N concentration was discussed, as well as the migration or transformation and release risk of N between different mediums. The results showed that spatial variations characteristics of N fractions were influenced by the lake topography and surrounding human activities. The content of total nitrogen (TN) in the sediments was 933.4 ~ 3006.8 mg/kg, with an average of 1835 mg/kg. The HN, RN, FN, and EN in sediments accounted for 66.85%, 21.35%, 6.82%, and 4.92% of TN, respectively. There was a significant correlation between each fraction of N and TN and also between different fractions of N (p < 0.01). Fitting by modified Langmuir model indicated that the adsorbed amounts of N in the sediments at maximum (Qmax) was, from greatest to least, southeast lake (2905.3 mg/kg) > southwest lake (1415.4 mg/kg) ≈ north lake (1424.6 mg/kg). Environmental parameters (pH, DO, C/N, etc.) affected the occurrence fraction of nitrogen, which could cause the persistent and increased risk of sustained release of high concentrations of endogenous N. N pollution in sediment and interstitial water is severe, and the risk of endogenous N release will gradually increase in the future.

Cyclic enrichment of chromium based on valence state transformation in metal-free photocatalytic reductive imprinted composite hydrogel.

Cr (VI) exists in anion form and can be reduced to positive charged Cr (III) under certain conditions. Can positive charged Cr (III) be continually used for absorbing Cr (VI) to achieve cyclic accumulation of chromium? In this paper, an ion imprinting material for adsorption of Cr (VI) was prepared by dispersing polypyrrole (PPy) in a gelatin/chitosan (Gel/CS) hydrogel network, named Gel/CS/PPy. Based on the conversion of Cr (VI) to Cr (III), a cyclic enrichment process including adsorption-photoreduction-fixation-readsorption of Cr (VI) was established in Gel/CS/PPy hydrogel. The composition and structure of the Gel/CS/PPy were analyzed by scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric (TGA), texture analyzer (Universal TA), zeta potential and ultraviolet-visible-near infrared spectra (UV-vis-NIR). The conversion of Cr (VI) and Cr (III) and its promoting effect on readsorption were verified by XPS. The results showed that Gel/CS/PPy has good adsorption capacity for Cr (VI) and excellent photocatalytic ability to reduce Cr (VI) to Cr (III). Cr (III)-loaded Gel/CS/PPy can be further used to adsorb Cr (VI) and showed good adsorption efficiency even after four cycles. The optimal operating condition for Cr (VI) adsorption is pH = 3; 2 g/L dose of Gel/CS/PPy; and the adsorption capacity of Cr (VI) was about 106.8 mg/g after six adsorption cycles. Since Gel/CS/PPy is composed of organic components, high purity chromium can be recovered by simple calcination method later. Therefore, the synthesized Gel/CS/PPy has great potential in the practical application of low concentration Cr (VI) treatment in water.

Photo/thermal response of polypyrrole-modified calcium alginate/gelatin microspheres based on helix-coil structural transition and the controlled release of agrochemicals.

Responsive controlled-release systems can not only improve the efficiency of agrochemical utilization but also increase crop yield and reduce environmental pollution caused by excessive use of agrochemicals. In this paper, the helix-coil structural transition of gelatin was adopted to construct a novel stimuli-responsive controlled-release system called polypyrrole/Ca-alginate/gelatin (PPy/Ca-alginate/Gel). In PPy/Ca-alginate/Gel, Ca-alginate and gelatin form a semi-interpenetrating network in which uncross-linked gelatin can undergo a free helix-coil structural transition due to the photothermal effect of PPy. The structural transition of gelatin will lead to changes in the functional groups and microstructure of semi-interpenetrating hydrogels and furthermore achieve the release of template agrochemical molecules embedded in hydrogels. By using carbendazim as a template molecule, the photothermal conversion and controlled release of PPy/Ca-alginate/Gel were systematically studied. After 600 s of light irradiation, its temperature could be increased by 17 ℃. The release of carbendazim in microspheres reached 91.8 % after 8 h of light irradiation, while it was only 13.3 % in the dark. The results indicated that PPy/Ca-alginate/Gel have excellent controlled-release and sustained-release properties and broad application potential in agriculture.

A green method based on electro-assisted and photo-assisted regeneration for removal of chromium(VI) from aqueous solution.

In general, spent adsorbent is regenerated using high-concentration chemicals. Although chemical regeneration is efficient, it often leads to adsorbent damage and secondary waste. To overcome these problems, electro-assisted and photo-assisted regeneration were proposed in this study for the remediation of hexavalent chromium (Cr(VI)). Filter paper was decorated with polyethylene glycol (PEG) and polypyrrole (PPy) to fabricate a FP/PEG/PPy nanocomposite, which could be used as an adsorbent for Cr(VI) with a high adsorption capacity. Moreover, it could be regenerated by electro-assisted or photo-assisted regeneration to reduce eluent use. As a result, secondary waste could be greatly reduced.