Zhengqing Yan

Spatiotemporal control of cell-cell reversible interactions using molecular engineering.

Manipulation of cell–cell interactions has potential applications in basic research and cell-based therapy. Herein, using a combination of metabolic glycan labelling and bio-orthogonal click reaction, we engineer cell membranes with β-cyclodextrin and subsequently manipulate cell behaviours via photo-responsive host-guest recognition. With this methodology, we demonstrate reversible manipulation of cell assembly and disassembly. The method enables light-controllable reversible assembly of cell–cell adhesion, in contrast with previously reported irreversible effects, in which altered structure could not be reused. We also illustrate the utility of the method by designing a cell-based therapy. Peripheral blood mononuclear cells modified with aptamer are effectively redirected towards target cells, resulting in enhanced cell apoptosis. Our approach allows precise control of reversible cell–cell interactions and we expect that it will promote further developments of cell-based therapy.

Programmed Bacteria Death Induced by Carbon Dots with Different Surface Charge

Based on a series of biochemical experiments for analysis and characterization, it is found that the uncharged C-dots have no effect on bacterial growth while the negatively charged and positively charged C-dots can induce bacteria apoptosis. For the positively charged C-dots, they can induce both bacteria apoptosis and bacteria death. These observations will provide new insights into bioapplications of carbon dots.

A pH-switched mesoporous nanoreactor for synergetic therapy

Zinc oxide nanoparticles (ZnO NPs), as a new type of pH-sensitive drug carrier, have received much attention. ZnO NPs are stable at physiological pH, but can dissolve quickly in the acidic tumor environment (pH < 6) to generate cytotoxic zinc ions and reactive oxygen species (ROS). However, the protein corona usually causes the non-specific degradation of ZnO NPs, which has limited their application considerably. Herein, a new type of pH-sensitive nanoreactor (ZnO-DOX@F-mSiO2-FA), aimed at reducing the non-specific degradation of ZnO NPs, is presented. In the acidic tumor environment (pH < 6), it can release cytotoxic zinc ions, ROS, and anticancer drugs to kill cancer cells effectively. In addition, the fluorescence emitted from fluorescein isothiocyanate (FITC)-labeled mesoporous silica (F-mSiO2) and doxorubicin (DOX) can be used to monitor the release behavior of the anticancer drug. This report provides a new method to avoid the non-specific degradation of ZnO NPs, resulting in synergetic therapy by taking advantage of ZnO NPs-induced oxidative stress and targeted drug release.

Autonomous and Continuous Stimuli-Responsive Polymer Surface for Antibacterial Application through Enzymatic Self-Propagating Reactions

Stimuli-responsive polymer materials inspired by biological materials have invoked increasing research interest; however, they still suffer from limitations such as finite amplified responses and poor sensitivity of the unstimulated parts. Herein, a new strategy for creating H+ -responsive polymer surfaces that are capable of transforming specific local fleeting stimuli into global macroscopic changes is described. The introduction of self-propagating reactions into the polymer-surface systems endows them with excellent stimuli-amplifying properties and response of the unstimulated parts. On the basis of this design, a polymer and enzymatic reaction were employed to enable a specific response to a stimulus and then lead to macroscopic changes of the surface. It is further shown that the prepared H+ -responsive polymer surfaces can be employed for antibacterial application. This work provides a good example of achieving autonomously reconfigurable materials that respond to local fleeting stimuli.

Photocontrolled Multidirectional Differentiation of Mesenchymal Stem Cells on an Upconversion Substrate

The effective guidance of mesenchymal stem cell (MSC) differentiation on a substrate by near-infrared (NIR) light is particularly attractive for tissue engineering and regenerative medicine. However, most of current substrates cannot control multidirectional differentiation of MSCs like natural tissues. Herein, a photocontrolled upconversion-based substrate was designed and constructed for guiding multidirectional differentiation of MSCs. The substrate enables MSCs to maintain their stem-cell characteristics due to the anti-adhesive effect of 4-(hydroxymethyl)-3-nitrobenzoic acid modified poly(ethylene glycol) (P1) attached on the upconversion substrate. Upon NIR irradiation, the P1 is released from the substrate by photocleavage. The detachment of P1 can change cell-matrix interactions dynamically. Moreover, MSCs cultured on the upconversion substrate can be specifically induced to differentiate to adipocytes or osteoblasts by adjusting the NIR laser. Our work provides a new way of using NIR-based upconversion substrate to modulate the multidirectional differentiation of MSCs.