Two-dimensional (2D) graphene oxide (GO) and molybdenum disulfide (MoS2) nanosheets (NSs) have been widely used as photothermal agents and as potential carriers of antitumor drugs. Their spatial thermal effects have been extensively explored for use at physiological and hyperthermic temperatures (37 to 46 °C). Furthermore, the modulation of the spatial thermal distributions with these NSs may have even more profound applications in the microstructural control of biomaterials at cryogenic temperatures (-196 to 37 °C). These applications include bioinspired microfabrication via freezing, food and drug freeze-drying, and biomaterial cryopreservation. However, such thermal effects of NSs and their applications at cryogenic temperatures had never been fully explored. Therefore, in this study, we have utilized the near-infrared laser induced photothermal effects of GO and MoS2 NSs to suppress the ice nucleation and ice crystal growth during warming of the biosamples. Using this approach, biological cells subjected to fast cooling to a deeply frozen state (-196 °C) were successfully recovered with high survival rates and full biological functionality. Thus, we provide a NS based effective approach to control the crystallization behaviors of water during warming at cryogenic temperatures, as NSs may have wide applications in both materials science and bioengineering.

In recent years, tremendous efforts have been made to investigate tribomaterials for triboelectric nanogenerators (TENGs), but due to their low performance there is still need of tribomaterials with new mechanisms for performance enhancement. Therefore, in this study, the potential of conducting polyaniline and tribonegative graphene oxide is exploited for performance enhancement of tribopositive material through a new mechanism of disturbing the equilibrium state inside the tribopositive material under an impact force. Thus, a TENG device made up of polymer with 700 µL polyaniline and 4 mg mL−1 graphene oxide as tribopositive and polydimethylsiloxane as a tribonegative layer with a dimension of 1 × 2 cm2 is able to produce an open‐circuit voltage of 314.92 V and a current density of 37.81 mA m−2 with a peak power density of 10.43 W m−2, which can directly power ON more than 175 white light‐emitting diodes. Amine group of polyaniline and its pathway to mobilize electrons inside the tribopositive material due to electron accepting ability of graphene oxide upon physical contact under external force are the main contributing factors toward performance enhancement. This work introduces a low cost, easy fabrication process with a new method for performance enhancement of tribopositive material to acquire a high performance TENGs.

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Investigation of oocyte membrane permeability plays a crucial role in fertility preservation, reproductive medicine, and reproductive pharmacology. However, the commonly used methods have disadvantages such as high time consumption, low efficiency, and cumbersome data processing. In addition, the developmental potential of oocytes after measurement has not been fully validated in previous studies. Moreover, oocytes can only maintain their best status in vitro within a very limited time. To address these limitations, we developed a novel multichannel microfluidic chip with newly designed micropillars that provide feasible and repeatable oocyte capture. The osmotic responses of three oocytes at different or the same cryoprotectant (CPA) concentrations were measured simultaneously, which greatly improved the measurement efficiency. Importantly, the CPA concentration dependence of mouse oocyte membrane permeability was found. Moreover, a neural network algorithm was employed to improve the efficiency and accuracy of data processing. Furthermore, analysis of fertilization and embryo transfer after perfusion indicated that the microfluidic approach does not damage the developmental potential of oocytes. In brief, we report a new method based on a multichannel microfluidic chip that enables synchronous and nondestructive measurement of the permeability of multiple oocytes.

Cryopreservation is essential to effectively extend the shelf life of delicate biomaterials while maintaining proper levels of cell functions. Cryopreservation requires a cryoprotective agent (CPA) to suppress intracellular ice formation during freezing, but it must be removed prior to clinical use due to its toxicity. Conventional multistep CPA loading and unloading approaches are time consuming, often creating osmotic shocks and causing mechanical injuries for biological samples. An efficient surface‐acoustic‐wave‐ (SAW‐) based lab‐on‐a‐chip (LoC) for fast loading and removal of CPAs is presented here. With the SAW‐based multistep CPA loading/removal approach, high concentration (3 m) CPA can be successfully loaded and removed in less than 1 min. Results show that the technique causes the least harm to umbilical cord matrix mesenchymal stem cells as compared to conventional method, and an average of 24% higher cell recovery rate is achieved, while preserving the integrity and morphology of the cells. This device is the first of its kind to combine high loading/unloading efficiency, high cell viability, and high throughput into one LoC device, offering not only a more efficient and safer route for CPA loading and removal from cells, but also paving the way for other cryopreservation‐dependent applications.