Fluorescence-based biosensor platforms have been intensively investigated not only to increase the sensitivity but also to improve the performance of biosensors. By exploiting metal from the macroscopic down to the nanoscopic surface, various architectures have been devised to manipulate fluorescence signals (enhancement, quenching) within near-optical fields. The interaction of a metallic surface with proximal fluorophores (in the range of 5-90 nm) has beneficial effects on optical properties such as an increased quantum yield, improved photostability and a reduced lifetime of fluorophores. This phenomenon called metal-enhanced fluorescence (MEF) has been extensively used in biosensory applications. However, their applications for biological analysis practically remain challenging in biological microenvironments. Therefore, this review primarily provides a general overview of MEF biosensor systems from the basic mechanism to state-of-the-art biological applications. The review also covers the pros and cons of MEF biosensor as well as discussions about further directions in biological perspectives.

In the field of tissue engineering, conductive hydrogels have been the most effective biomaterials to mimic the biological and electrical properties of tissues in the human body. The main advantages of conductive hydrogels include not only their physical properties but also their adequate electrical properties, which provide electrical signals to cells efficiently. However, when introducing a conductive material into a non-conductive hydrogel, a conflicting relationship between the electrical and mechanical properties may develop. This review examines the strengths and weaknesses of the generation of conductive hydrogels using various conductive materials such as metal nanoparticles, carbons, and conductive polymers. The fabrication method of blending, coating, and in situ polymerization is also added. Furthermore, the applications of conductive hydrogel in cardiac tissue engineering, nerve tissue engineering, and bone tissue engineering and skin regeneration are discussed in detail.

Mesenchymal stem cell (MSC) encapsulation technique has long been emerged in tissue engineering as it plays an important role in implantation of stem cells to regenerate a damaged tissue. MSC encapsulation provides a mimic of a three-dimensional (3D) in vivo environment to maintain cell viability and to induce the stem cell differentiation which regulates MSC fate into multi-lineages. Moreover, the 3D matrix surrounding MSCs protects them from the human innate immune system and allows the diffusion of biomolecules such as oxygen, cytokines, and growth factors. Therefore, many technologies are being developed to create MSC encapsulation platforms with diverse materials, shapes, and sizes. The conditions of the platform are determined by the targeted tissue and translation method. This review introduces several details of MSC encapsulation technologies such as micromolding, electrostatic droplet extrusion, microfluidics, and bioprinting and their application for tissue regeneration. Lastly, some of the challenges and future direction of MSC encapsulation technologies as a cell therapy-based tissue regeneration method will be discussed.

A 3D touchless display is created where a human finger position is visualized in structural colors of a soft photonic crystal.

A facile approach for the highly luminescent and biocompatible CsPbBr₃@SiO₂ core–shell PNCs was developed. The dual biological roles of these PNCs are demonstrated, offering new directions to the stable PNCs for a variety of biomedical applications.

Background: The topographical cue is major influence on skeletal muscle cell culture because the structure is highly organized and consists of long parallel bundles of multinucleated myotubes that are formed by differentiation and fusion of myoblast satellite cells. In this technical report, we fabricated a multiscale scaffold using electrospinning and poly (ethylene glycol) (PEG) hydrogel micropatterns to monitor the cell behaviors on nano- and micro-alignment combined scaffolds with different combinations of angles. Results: We fabricated multiscale scaffolds that provide biocompatible and extracellular matrix (ECM)-mimetic environments via electrospun nanofiber and PEG hydrogel micro patterning. MTT assays demonstrated an almost four-fold increase in the proliferation rate during the 7 days of cell culture for all of the experimental groups. Cell orientation and elongation were measured to confirm the myogenic potential. On the aligned fibrous scaffolds, more than 90% of the cells were dispersed ± 20° of the fiber orientation. To determine cell elongation, we monitored nuclei aspect ratios. On a random nanofiber, the cells demonstrated an aspect ratio of 1.33, but on perpendicular and parallel nanofibers, the aspect ratio was greater than 2. Myosin heavy chain (MHC) expression was significantly higher i) on parallel compared to random fibers, ii) the 100 μm compared to the 200 μm line pattern. We confirmed the disparate trends of myotube formation that can be provoked through multi-dimensional scaffolds. Conclusion: We studied more favorable environments that induce cell alignment and elongation for myogenesis by combining nano- and micro-scale patterns. The fabricated system can serve as a novel multi-dimensional platform to study in vitro cell behaviors.