Dorsey Taylor B, Grath Alexander, Wang Annling, Xu Cancan, Hong Yi, Dai Guohao
Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180.
Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180.
Bioact Mater. 2018 Mar;3(1):64-73. doi: 10.1016/j.bioactmat.2017.05.005. Epub 2017 May 13.
Bioactive signals play many important roles on cell function and behavior. In most biological studies, soluble biochemical cues such as growth factors or cytokines are added directly into the media to maintain and/or manipulate cell activities . However, these methods cannot accurately mimic certain biological signaling motifs, which are often immobilized to extracellular matrix and also display spatial gradients that are critical for tissue morphology. Besides biochemical cues, biophysical properties such as substrate stiffness can influence cell behavior but is not easy to manipulate under conventional cell culturing practices. Recent development in photocrosslinkable hydrogels provides new tools that allow precise control of spatial biochemical and biophysical cues for biological applications, but doing so requires a comprehensive study on various hydrogel photochemistry kinetics to allow thorough photocrosslink reaction while maintain protein bioactivities at the same time. In this paper, we studied several photochemistry reactions and evaluate key photochemical parameters, such as photoinitiators and ultra-violet (UV) exposure times, to understand their unique contributions to undesired protein damage and cell death. Our data illustrates the retention of protein function and minimize of cell health during photoreactions requires careful selection of photoinitiator type and concentration, and UV exposure times. We also developed a robust method based on thiol-norbornene chemistry for independent control of hydrogel stiffness and spatial bioactive patterns. Overall, we highlight a class of bioactive hydrogels to stiffness control and site specific immobilized bioactive proteins/peptides for the study of cellular behavior such as cellular attraction, repulsion and stem cell fate.
生物活性信号在细胞功能和行为中发挥着许多重要作用。在大多数生物学研究中，可溶性生化信号，如生长因子或细胞因子，被直接添加到培养基中以维持和/或操纵细胞活动。然而，这些方法无法准确模拟某些生物信号基序，这些基序通常固定在细胞外基质上，并且还呈现出对组织形态至关重要的空间梯度。除了生化信号外，诸如底物硬度等生物物理特性也会影响细胞行为，但在传统细胞培养实践中不易操控。可光交联水凝胶的最新进展提供了新工具，能够精确控制用于生物应用的空间生化和生物物理信号，但要做到这一点，需要对各种水凝胶光化学动力学进行全面研究，以实现彻底的光交联反应，同时保持蛋白质生物活性。在本文中，我们研究了几种光化学反应，并评估了关键光化学参数，如光引发剂和紫外线（UV）照射时间，以了解它们对不期望的蛋白质损伤和细胞死亡的独特影响。我们的数据表明，在光反应过程中保持蛋白质功能并使细胞健康状况降至最低，需要仔细选择光引发剂类型和浓度以及紫外线照射时间。我们还基于硫醇-降冰片烯化学开发了一种强大的方法，用于独立控制水凝胶硬度和空间生物活性模式。总体而言，我们强调了一类用于硬度控制的生物活性水凝胶以及用于研究细胞行为（如细胞吸引、排斥和干细胞命运）的位点特异性固定生物活性蛋白质/肽。
