Cell cryopreservation has evolved as an important technology required for supporting various cell-based applications, such as stem cell therapy, tissue engineering, and assisted reproduction. Recent times have witnessed an increase in the clinical demand of these applications, requiring urgent improvements in cell cryopreservation. However, cryopreservation technology suffers from the issues of low cryopreservation efficiency and cryoprotectant (CPA) toxicity. Application of advanced biotechnology tools can significantly improve post-thaw cell survival and reduce or even eliminate the use of organic solvent CPAs, thus promoting the development of cryopreservation. Herein, based on the different cryopreservation mechanisms available, we provide an overview of the applications and achievements of various biotechnology tools used in cell cryopreservation, including trehalose delivery, hydrogel-based cell encapsulation technique, droplet-based cell printing, and nanowarming, and also discuss the associated challenges and perspectives for future development.
Organic field-effect transistors (OFETs) are fabricated using organic semiconductors (OSCs) as the active layer in the form of thin films. Due to its advantages of high sensitivity, low cost, compact integration, flexibility, and printability, OFETs have been used extensively in the sensing area. For analysis platforms, the construction of sensing layers is a key element for their efficient detection capability. The strategy used to immobilize biomolecules in these devices is especially important for ensuring that the sensing functions of the OFET are effective. Generally, analysis platforms are developed by modifying the gate/electrolyte or OSC/electrolyte interface using biomolecules, such as enzymes, antibodies, or deoxyribonucleic acid (DNA) to ensure high selectivity. To provide better or more convenient biological immobilization methods for researchers in this field and thereby improve detection sensitivity, this review summarizes recent developments in the immobilization strategies used for biological macromolecules in OFETs, including cross-linking, physical adsorption, embedding, and chemical covalent binding. The influences of biomolecules on device performance are also discussed.
Fundamental research and practical applications have examined the manipulation of gas bubbles on open surfaces in low-surface-tension, high-pressure, and high-acidity, -alkalinity, or -salinity environments. However, to the best of our knowledge, efficient and general approaches to achieve the smart manipulation of gas bubbles in these harsh environments are limited. Herein, a Fluorinert-infused shape-gradient slippery surface (FSSS) that could effectively regulate the behavior of gas bubbles in harsh environments was successfully fabricated. The unique capability of FSSS was mainly attributed to the properties of Fluorinert, which include chemical inertness and incompressibility. The shape-gradient morphology of FSSS could induce asymmetric driving forces to move gas bubbles directionally on open surfaces. Factors influencing gas bubble transport on FSSS, such as the apex angle of the slippery surface and the surface tension of the aqueous environment, were carefully investigated, and large apex angles were found to result in large initial transport velocities and short transport distances. Lowering the surface tension of the aqueous environment is unfavorable to bubble transport. Nevertheless, FSSS could transport gas bubbles in aqueous environments with surface tensions as low as 28.5 ± 0.1 mN/m, which is lower than that of many organic solvents (e.g., formamide, ethylene glycol, and dimethylformamide). In addition, FSSS could also realize the facile manipulation of gas bubbles in various aqueous environments, e.g., high pressure (~ 6.8 atm), high acidity (1 mol/L H2SO4), high alkalinity (1 mol/L NaOH), and high salinity (1 mol/L NaCl). The current findings provide a source of knowledge and inspiration for studies on bubble-related interfacial phenomena and contribute to scientific and technological developments for controllable bubble manipulation in harsh environments.
Photodynamic therapy (PDT) is a promising cancer therapy due to the evident advantages of a rapid curative effect, minimal or non-invasiveness, and circumvention of drug resistance. However, the hydrophobicity of photosensitizers and the hypoxic tumor microenvironment in solid tumors reduce the therapeutic effect of PDT immensely. Herein, we construct a programmable hybrid mesoporous silica nanoparticle/DNA nanogel (H-DNA nanogel) for enhanced PDT. The H-DNA nanogel is constituted with a virus-like mesoporous silica nanoparticle (VMSN) as the core to provide an appropriate nano-interface and a self-assembly programmable DNA hydrogel layer based on rolling circle amplification (RCA) as the shell. Two kinds of G-quadruplex structures inserted with a hemin and zinc phthalocyanine (ZnPc) photosensitizer are introduced into the H-DNA nanogel by base pairing. The two modules of G-quadruplex structure work as an oxygen supplement in the hypoxic tumor microenvironment and increase the yield of singlet oxygen, respectively. Our hybrid DNA nanogel system provides a modular platform for efficient cancer PDT and has great potential in the broader biomedical field.
Tautomers are structural isomers that readily interconvert and may exhibit different properties. The effect of solvent on tautomeric equilibria in solution has been a subject of some research. Tautomer solvate is less common, and the role of solvent in the crystallization of tautomer solvate remains an interesting topic. In this work, we used 6-amino-1,3-dimethyl-5-nitrosouracil (NAU) as the tautomeric model material, which can present in nitrone–enamine form (Tautomer A) or oxime–imine form (Tautomer B). A solvate with NAU/DMSO ratio of 1:1 was discovered and characterized using single/powder X-ray diffraction and thermogravimetry. The crystal structure of NAU·DMSO was determined for the first time, where only Tautomer A was formed in the tautomeric crystal. Quantum chemical calculation and molecular dynamics simulation were conducted to determine the tautomeric form in DMSO solution. Electrostatic potential analysis, radial distribution function analysis, and binding energy suggested possible DMSO–NAU interaction modes and stable tautomer complexes in solution. Tautomer A-containing complexes were found to dominate in solution, as verified by comparing predicted and experimental 1H NMR spectra. Findings reveal that the hydrogen bonding between DMSO and NAU is similar in solution and in NAU–DMSO solvate crystal, which helps preserve the form of Tautomer A during solvate crystallization.
Visible light photocatalytic CO2 conversion is a promising solution to global warming and energy shortage. Herein, we build a well-designed bridge-like nanostructure, that is, the phosphonated Ru complex (RuP) light absorber–TiO2 bridge–Cu catalyst. In this nanostructure, brookite TiO2 serving as a bridge is spatially connected to the RuP and Cu on each of its sides and could thus physically separate the photoexcited holes and electrons over the RuP and Cu, respectively. Given its effective charge separation, this RuP–TiO2–Cu assembly exhibits superior CO2 photoreduction activity relative to RuP–SiO2–Cu under visible light irradiation (λ > 420 nm). The catalytic activity is further optimized by adopting brookite TiO2 with various electronic band structures. Results reveal the rapid movement of electrons from the RuP through the conduction band of TiO2 and finally to the Cu surface. This property is crucial in CO2 photoreduction activity.