Silk Hydrogel for Tissue Engineering: A Review.

AIM: This review aims to explore the importance of silk hydrogel and its potential in tissue engineering (TE). BACKGROUND: Tissue engineering is a procedure that incorporates cells into the scaffold materials with suitable growth factors to regenerate injured tissue. For tissue formation in TE, the scaffold material plays a key role. Different forms of silk fibroin (SF), such as films, mats, hydrogels, and sponges, can be easily manufactured when SF is disintegrated into an aqueous solution. High precision procedures such as micropatterning and bioprinting of SF-based scaffolds have been used for enhanced fabrication. REVIEW RESULTS: In this narrative review, SF physicochemical and mechanical properties have been presented. We have also discussed SF fabrication techniques like electrospinning, spin coating, freeze-drying, and physiochemical cross-linking. The application of SF-based scaffolds for skeletal, tissue, joint, muscle, epidermal, tissue repair, and tympanic membrane regeneration has also been addressed. CONCLUSION: SF has excellent mechanical properties, tunability, biodegradability, biocompatibility, and bioresorbability. CLINICAL SIGNIFICANCE: Silk hydrogels are an ideal scaffold matrix material that will significantly impact tissue engineering applications, given the rapid scientific advancements in this field.

Light sheet microscopy for histopathology applications.

Light sheet microscopy (LSM) is an evolving optical imaging technique with a plane illumination for optical sectioning and volumetric imaging spanning cell biology, embryology, and in vivo live imaging. Here, we focus on emerging biomedical applications of LSM for tissue samples. Decoupling of the light sheet illumination from detection enables high-speed and large field-of-view imaging with minimal photobleaching and phototoxicity. These unique characteristics of the LSM technique can be easily adapted and potentially replace conventional histopathological procedures. In this review, we cover LSM technology from its inception to its most advanced technology; in particular, we highlight the human histopathological imaging applications to demonstrate LSM's rapid diagnostic ability in comparison with conventional histopathological procedures. We anticipate that the LSM technique can become a useful three-dimensional imaging tool for assessing human biopsies in the near future.

Label-free nanoscale characterization of red blood cell structure and dynamics using single-shot transport of intensity equation.

We report the results of characterization of red blood cell (RBC) structure and its dynamics with nanometric sensitivity using transport of intensity equation microscopy (TIEM). Conventional transport of intensity technique requires three intensity images and hence is not suitable for studying real-time dynamics of live biological samples. However, assuming the sample to be homogeneous, phase retrieval using transport of intensity equation has been demonstrated with single defocused measurement with x-rays. We adopt this technique for quantitative phase light microscopy of homogenous cells like RBCs. The main merits of this technique are its simplicity, cost-effectiveness, and ease of implementation on a conventional microscope. The phase information can be easily merged with regular bright-field and fluorescence images to provide multidimensional (three-dimensional spatial and temporal) information without any extra complexity in the setup. The phase measurement from the TIEM has been characterized using polymeric microbeads and the noise stability of the system has been analyzed. We explore the structure and real-time dynamics of RBCs and the subdomain membrane fluctuations using this technique.