MXenes are currently one of the most widely studied two-dimensional materials due to their properties. However, obtaining highly dispersed MXene materials in organic solvent remains a significant challenge for current research. Here, we have developed a method called the tuned microenvironment method (TMM) to prepare a highly concentrated Ti 3 C 2 T x organic solvent dispersion by tuning the microenvironment of Ti 3 C 2 T x . The as-proposed TMM is a simple and efficient approach, as Ti 3 C 2 T x can be dispersed in N,N-dimethylformamide and other solvents by stirring and shaking for a short time, without the need for a sonication step. The delaminated single-layer MXene yield can reach 90% or greater, and a large-scale synthesis has also been demonstrated with TMM by delaminating 30 g of multilayer Ti 3 C 2 T x raw powder in a one-pot synthesis. The synthesized Ti 3 C 2 T x nanosheets dispersed in an organic solvent possess a clean surface, uniform thickness, and large size. The Ti 3 C 2 T x dispersed in an organic solvent exhibits excellent oxidation resistance even under aerobic conditions at room temperature. Through the experimental investigation, the successful preparation of a highly concentrated Ti 3 C 2 T x organic solvent dispersion via TMM can be attributed to the following factors: (1) the intercalation of the cation can lead to the change in the hydrophobicity and surface functionalization of the material; (2) proper solvent properties are required in order to disperse MXene nanosheets well. To demonstrate the applicability of the highly concentrated Ti 3 C 2 T x organic solvent dispersion, a composite fiber with excellent electrical conductivity is prepared via the wet-spinning of a Ti 3 C 2 T x (dispersed in DMF) and polyacrylonitrile mixture. Finally, various types of MXenes, such as Nb 2 CT x , Nb 4 C 3 T x , and Mo 2 Ti 2 C 3 T x , can also be prepared as highly concentrated MXene organic solvent dispersions via TMM, which proves the universality of this method. Thus, it is expected that this work demonstrates promising potential in the research of the MXene material family.

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Graphene oxide (GO) possessing plenty of hydroxyls and carboxyls is often used in the field of biomedicine. To improve its water solubility and biocompatibility, 6-armed poly(ethylene glycol) (PEG) was bonded on the surface of GO sheets via a facile amidation process to form the universal drug delivery platform (GO-PEG 10K-6arm ) with a 200 nm size in favor of the enhanced permeability and retention effect. Herein, we prepared the stable and biocompatible platform of GO-PEG 10K-6arm under mild conditions and characterized the chemical structure and micromorphology via thermogravimetric analysis and atomic force microscopy. This nanosized GO-PEG 10K-6arm was found to be of very low toxicity to human normal cells of 293T and tumor cells of CAL27, MG63, and HepG2. Moreover, oridonin and methotrexate (MTX), widely used hydrophobic cancer chemotherapy drugs, were compounded with GO-PEG 10K-6arm via π−π stacking and hydrophobic interactions so as to afford nanocomplexes of oridonin@ GO-PEG 10K-6arm and MTX@GO-PEG 10K-6arm , respectively. Both nanocomplexes could quickly enter into tumor cells, which was evidenced by inverted fluorescence microscopy using fluorescein isothiocyanate as a probe, and they both showed remarkably high cytotoxicity to the tumor cells of CAL27, MG63, and HepG2 within a broad range of concentration in comparison with free drugs. This kind of nanoscale drug delivery system based on GO-PEG 10K-6arm may have potential applications in biomedicine, and GO-PEG 10K-6arm would be a universal and available carrier for extensive hydrophobic anticarcinogens.

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Production of human α-lactalbumin (hα-LA) transgenic cloned dairy goats has great potential in improving the nutritional value and perhaps increasing the yield of dairy goat milk. Here, a mammary-specific expression vector 5A, harboring goat β-lactoglobulin (βLG) promoter, the hα-LA gene, neo(r) and EGFP dual markers, was constructed. Then, it was effectively transfected into goat mammary epithelial cells (GMECs) and the expression of hα-LA was investigated. Both the hα-LA transcript and protein were detected in the transfected GMECs after the induction of hormonal signals. In addition, the 5A vector was introduced into dairy goat fetal fibroblasts (transfection efficiency ≈60-70%) to prepare competent transgenic donor cells. A total of 121 transgenic fibroblast clones were isolated by 96-well cell culture plates and screened with nested-PCR amplification and EGFP fluorescence. After being frozen for 8 months, the transgenic cells still showed high viabilities, verifying their ability as donor cells. Dairy goat cloned embryos were produced from these hα-LA transgenic donor cells by somatic cell nuclear transfer (SCNT), and the rates of fusion, cleavage, and the development to blastocyst stages were 81.8, 84.4, and 20.0%, respectively. A total of 726 reconstructed embryos derived from the transgenic cells were transferred to 74 recipients and pregnancy was confirmed at 90 days in 12 goats. Of six female kids born, two carried hα-LA and the hα-LA protein was detected in their milk. This study provides an effective system to prepare SCNT donor cells and transgenic animals for human recombinant proteins.