Construction of Polymeric DNA Network and Application for Cell Manipulation

Comprehensive Summary Deoxyribonucleic acid(DNA)is a biomacromolecule,as well as a polymeric material,whose sequences with different manipulative structures enable them to implement a series of functions,such as reorganization,target,and catalysis.Compared to existing traditional materials incapable of multifunctional integration,the polymeric DNA network is a form of material that can achieve functional integration while maintaining specific DNA properties.Furthermore,precise target enabled by DNA network is one of the most essential components of cellular manipulation.Hence,the DNA network is indispensable and irreplaceable to cell manipulation that it is a versatile tool for the understanding of basic laws of living life and treatments of diseases,such as cell isolation,cell delivery,and cell interference.Herein,the construction of polymeric DNA network is briefly introduced from the aspects of assembly modules,construction methods,and properties.

Manipulation of collagen synthesis influences progenitor cell engraftment and angiomyogenesis

Myocardial infarction(MI)results in loss of cardiomyocytes(CM) in the ischemic area of the heart followed by an inflammatory response and replacement of contractile CM with fibrosis.Myocardial fibrosis,a key contributor to cardiac dysfunction after MI,presents as a secondary response to the pathophysiological remodeling of long-standing disease including ischemia,obstruction,and microvascular abnormalities.Cardiac fibroblasts and myofibroblasts are responsible for post-MI remodeling which occurs via regulation of extracellular matrix (ECM),presenting as increased collagenⅠandⅢinto the interstitial and perivascular space.In addition to the pluripotency of stem cells following stem/ progenitor cell transplantation,decreased apoptosis, hypertrophy,and fibrosis in the infarcted heart have been demonstrated.This has made transplantation of progenitor/stem cells a primary research focus in the field of tissue regeneration.Unfortunately,the accumulation of ECM and myofibroblasts in areas of tissue injury presents a barrier that can impair penetration of reparative stem/progenitor cells mobilized from peripheral reservoirs.Therefore,cardiac fibroblast production and degradation of ECM are critical in regulating cardiac remodeling and stem/progenitor cell mobilization.This study used transgenic mice overexpressing adenylyl cyclaseⅥ(AC6) in which collagen synthesis was decreased to determine the role of collagen deposition on the engraftment of iPSC from a tri-cell patch applied to infarcted area after MI.

DESIGN AND FABRICATION OF A MICRO THERMAL ACTUATOR FOR CELLULAR GRASPING

The development of a novel polymer-based micro robotic gripper that can be actuated in a fluidic medium is presented in this paper.Our current work is to explore new materials and designs for thermal actuators to achieve micromanipulation of live biological cells.We used parylene C to encapsulate a metal heater,resulting in effectively a tri-layered thermal actuator.Parylene C is a bio-compatible dielectric polymer that can serve as a barrier to various gases and chemicals. Therefore,it is suitable to serve as a thermal/electrical/chemical isolation material for protecting the metal heater from exposing to an aqueous environment.We have demonstrated parylene actuators (2mm×100μm×0.5μm)to operate in an aqueous environment using 10 to 80mW input power.The temperature of these actuators at full deflection was estimated to be～60℃,which is much lower than the typical requirement of>100℃ to actuate other conventional MEMS actuators.Danio rerio follicles in fluidic medium were captured successfully using these actuators.Moreover,these actuators were found to be responsive to moderate rise in environmental temperature,and hence,we could vary the fluidic medium temperature to actuate trimorphs on a chip without any input of electrical energy, i.e.,raising the fluidic temperature from 23℃ to 60℃ could actuate the trimorphs to grasp follicles of ～1mm size in diameter.At 60℃,the embryos inside the follicles were observed to be alive,i.e.,they were still moving in the biological fluid isolated by the follicle membrane.The smallest follicles grasped were～500μm in diameter using 800μm×130μm×0.6μm actuators.The fabrication process,modeling, and optimization of the trimorph actuators are presented.Based on the successful operation of these polymer-based actuators,we are currently developing multifinger thermal microgrippers for cellular grasping and manipulation,which can potentially be hybridly integrated with circuits for computer control.

Minimally manipulated autologous adherent bone marrow cells (ABMCs):a promising cell therapy of spinal cord injury

Spinal cord injury（SCI）is a devastating ailment that results in drastic life style alterations for the patients and their family members（Mc Donald and Sadowsky,2002）.Damage post injury causes necrosis,edema,hemorrhage and vasospasm.Post injury,secondary damage is caused by ischemia,

Two-dimensional model of vesicle adhesion on curved substrates

We develop a two dimensional model of a vesicle adhered on a curved substrate via long-range molecular interactions while subjected to a detachment force. The relationship between the force and displacement of the vesicle is investigated as a function of the substrate shape. It is shown that both the force- displacement relationship and the maximum force at pull-off are significantly dependent on the substrate shape. The results suggest that probes with different tip shapes may be designed for cell manipulation. For example, we demonstrate that a vesicle can be pulled off a fiat surface using a probe with a curved tip.

Single-cell metabolite analysis on a microfluidic chip

Metabolites can directly reflect and modulate cell responses and phenotypical changes by influencing energy balances,intercellular signals,and many other cellular functions throughout the lifespan of cells.Taking into account the heterogeneity of cells,single-cell metabolite analysis offers an insight into the functional process within one cell.Microfluidics as a powerful tool has attracted significant interest in the single-cell metabolite analysis field.The microfluidic platform is possible to observe,classify,and stimulate individual cells.It can also transport single-cell to subsequent analysis steps in a fast and controllable way to determine and analyze the composition and content of metabolites.The reviews of topics in microfluidics for single-cell metabolite analysis have been published in the past few years.However,most of them focused on metabolite analysis with mass spectrometry.Here,we covered the advances of microfluidic devices for single-cell metabolite analysis,with a focus on single-cell isolation and manipulation.What is more,we summarized the detection methods and applications of single-cell metabolites.

On-chip 3D rotation of oocyte based on a vibration-induced local whirling flow

We propose a novel on-chip 3D cell rotation method based on a vibration-induced flow.When circular vibration is applied to a microchip with micropillar patterns,a highly localized whirling flow is induced around the micropillars.The direction and velocity of this flow can be controlled by changing the direction and amplitude of the applied vibration.Furthermore,this flow can be induced on an open chip structure.In this study,we adopted a microchip with three micropillars arranged in a triangular configuration and an xyz piezoelectric actuator to apply the circular vibration.At the centre of the micropillars,the interference of the vibration-induced flows originating from the individual micropillars induces rotational flow.Consequently,a biological cell placed at this centre rotates under the influence of the flow.Under three-plane circular vibrations in the xy,xz or yz plane,the cell can rotate in both the focal and vertical planes of the microscope.Applying this 3D cell rotation method,we measured the rotational speeds of mouse oocytes in the focal and vertical planes as 63.7±4.0°s^(−1) and 3.5±2.1°s^(−1),respectively.Furthermore,we demonstrated the transportation and rotation of the mouse oocytes and re-positioned their nuclei into a position observable by microscope.

Photo-responsive polymer materials for biological applications

Photo-responsive polymer materials from zero-dimensional micelles, two-dimensional surfaces to three-dimensional hydrogels have been designed, synthesized and applied for various biological fields including drug delivery and cell manipulation. Many remarkable works have been reported, revealing the advantages of photo-responsive polymers such as noninvasion and spatiotemporal control. In this review, we briefly summarized the remarkable progress of photo-responsive polymers with irreversible or reversible moieties and their further biological applications. The future opportunities and challenges of photo-responsive polymer materials are also proposed.