A surface-engineered NIR light-responsive actuator for controllable modulation of collective cell migration

Light-mediated protein functionalization of photoclickable hydrogel interface for selective cell capture and dot blotting assay

The construction of versatile functional hydrogel interfaces holds promising prospects in biosensing and bioengineering. Herein, we introduced a light-induced protein conjugation strategy for on-demand surface modification of hydrogel interface based on the photoclick cyclization between primary amine and o-nitrobenzyl alcohol. We achieved the on-demand protein conjugation by grafting the molecular plugin, 4-(hydroxymethyl)-3-nitrobenzoic acid (HNBA), onto the hydrogel surface, followed by the mask-aided photoclick reaction with the protein of interest. This method enables the creation of protein patterns on hydrogel interface with a lower limit of pattern width at ∼70 μm. With this method, we demonstrated the surface engineering of epidermal growth factor (EGF) on hydrogel interface for selective capture of EGF receptor-positive cancer cells with an efficiency over 80%. Moreover, we applied the mask-aided photoclick conjugation method for antigen capture and developed a photoclickable hydrogel interface-based dot blotting assay. Due to the high-efficient antigen capture of photoclick conjugation, the photoclickable hydrogel interface-based dot blotting assay shows improved sensitivity for antigen detection with a limit of detection as 0.065 ng. We believed that this light-induced protein conjugation method holds the potential as a robust strategy for the construction of bioactive hydrogel interfaces for various bio-related applications.

Soft nano and microstructures for the photomodulation of cellular signaling and behavior

Photoresponsive soft materials are everywhere in the nature, from human's retina tissues to plants, and have been the inspiration for engineers in the development of modern biomedical materials. Light as an external stimulus is particularly attractive because it is relatively cheap, noninvasive to superficial biological tissues, can be delivered contactless and offers high spatiotemporal control. In the biomedical field, soft materials that respond to long wavelength or that incorporate a photon upconversion mechanism are desired to overcome the limited UV-visible light penetration into biological tissues. Upon light exposure, photosensitive soft materials respond through mechanisms of isomerization, crosslinking or cleavage, hyperthermia, photoreactions, electrical current generation, among others. In this review, we discuss the most recent applications of photosensitive soft materials in the modulation of cellular behavior, for tissue engineering and regenerative medicine, in drug delivery and for phototherapies.

Design, Bioanalytical, and Biomedical Applications of Aptamer-Based Hydrogels

Aptamers are special types of single-stranded DNA generated by a process called systematic evolution of ligands by exponential enrichment (SELEX). Due to significant advances in the chemical synthesis and biotechnological production, aptamers have gained considerable attention as versatile building blocks for the next generation of soft materials. Hydrogels are high water-retainable materials with a three-dimensional (3D) polymeric network. Aptamers, as a vital element, have greatly expanded the applications of hydrogels. Due to their biocompatibility, selective binding, and molecular recognition, aptamer-based hydrogels can be utilized for bioanalytical and biomedical applications. In this review, we focus on the latest strategies of aptamer-based hydrogels in bioanalytical and biomedical applications. We begin this review with an overview of the underlying design principles for the construction of aptamer-based hydrogels. Next, we will discuss some bioanalytical and biomedical applications of aptamer-based hydrogel including biosensing, target capture and release, logic devices, gene and cancer therapy. Finally, the recent progress of aptamer-based hydrogels is discussed, along with challenges and future perspectives.