Browsing by Author "Zhang, Haonan"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Enhancing Conductivity and Self-Healing Properties of PVA/GEL/OSA Composite Hydrogels by GO/SWNTs for Electronic Skin
    Chen, Xiaohu; Zhang, Haonan; Cui, Jiashu; Wang, Yanen; Li, Mingyang; Zhang, Juan; Wang, Changgeng; Liu, Zhisheng; Wei, Qinghua (MDPI, 2023-02-15)
    The use of flexible, self-healing conductive hydrogels as a type of typical electronic skin with the function of transmitting sensory signals has attracted wide attention in the field of biomaterials. In this study, composite hydrogels based on polyvinyl alcohol (PVA), gelatin (GEL), oxidized sodium alginate (OSA), graphene oxide (GO), and single-walled carbon nanotubes (SWNTs) were successfully prepared. The hydrogen and imine bonding of the composite hydrogels gives them excellent self-healing properties. Their self-healing properties restore 68% of their breaking strength and over 95% of their electrical conductivity. The addition of GO and SWNTs enables the PGO-GS hydrogels to achieve a compressive modulus and conductivity of 42.2 kPa and 29.6 mS/m, which is 8.2 times and 1.5 times that of pure PGO, respectively. Furthermore, the PGO-GS hydrogels can produce profound feedback signals in response to deformation caused by external forces and human movements such as finger flexion and speech. In addition, the PGO-GS hydrogels exhibit superior biocompatibility compared to PGO. All of these results indicate that the PGO-GS hydrogels have great potential with respect to future applications in the field of electronic skin.
  • Thumbnail Image
    Investigating Cell Viscoelastic Properties with Nanonet Force Microscopy
    Zhang, Haonan (Virginia Tech, 2022-08-04)
    Determining the mechanical properties of living cells accurately and repeatably is critical to understanding developmental, disease, and repair biology. The cellular environment is composed of fibrous proteins of a mix of diameters organized in random and aligned configurations. In the past two decades, several methods, including modified atomic force microscopy (AFM) and micro-pipette aspiration have been developed to measure cellular viscoelastic properties at single-cell resolution. We inquired if the fibrous environment affected cellular mechanobiology. Using our non-electrospinning Spinneret based Tunable Engineered Parameters (STEP) fiber manufacturing platform, we developed fused nanonets to measure single-cell forces and viscoelasticity. Using computer-controlled probes, we stretched single cells attached to two-fiber and three-fiber systems precisely and recorded the relaxation response of cells. The viscoelastic properties were determined by fitting the data to the standard linear viscoelastic solid model (SLS), which includes a spring (k0) in parallel with a spring (km)-damper (cm) series. In cases in which cells are seeded on two fibers, we tested hMSCs and BJ-5TA cells, and the viscoelastic components measurements k0, km, and cm are 26.16 ± 3.38 nN/µm, 5.81 ± 0.81 nN/µm, and 41.15 ± 5.97 nN-s/µm, respectively for hMSCs, while the k0, km, and cm, measurements of BJ-5TA cells are 20.02 ± 2.89 nN/µm, 4.62 ± 0.75 nN/µm, and 45.46 ± 6.00 nN-s/µm respectively. Transitioning to the three-fiber system resulted in an overall increase in native contractility of the cells while allowing us to understand how the viscoelastic response was distributed with an increasing number of fibers. Viscoelastic experiments were done twice. First, we pulled on the outermost fiber similar to the two-fiber case. The cell was then allowed to rest for two hours, sufficient time to regain its pre-stretching contractility. The cell was then excited by pulling on the middle fiber. The experimental results of cell seeding on three fibers proved that the viscoelastic property measurements depend on the excitation position. Overall, we present new knowledge on the cellular viscoelasticity of cells attached to ECM-mimicking fibers.
  • Thumbnail Image
    Mitotic outcomes and errors in fibrous environments
    Jana, Aniket; Sarkar, Apurba; Zhang, Haonan; Agashe, Atharva; Wang, Ji; Paul, Raja; Gov, Nir S.; DeLuca, Jennifer G.; Nain, Amrinder S. (National Academy of Sciences, 2023-02-27)
    During mitosis, cells round up and utilize the interphase adhesion sites within the fibrous extracellular matrix (ECM) as guidance cues to orient the mitotic spindles. Here, using suspended ECM-mimicking nanofiber networks, we explore mitotic outcomes and error distribution for various interphase cell shapes. Elongated cells attached to single fibers through two focal adhesion clusters (FACs) at their extremities result in perfect spherical mitotic cell bodies that undergo significant 3-dimensional (3D) displacement while being held by retraction fibers (RFs). Increasing the number of parallel fibers increases FACs and retraction fiber-driven stability, leading to reduced 3D cell body movement, metaphase plate rotations, increased interkinetochore distances, and significantly faster division times. Interestingly, interphase kite shapes on a crosshatch pattern of four fibers undergo mitosis resembling single-fiber outcomes due to rounded bodies being primarily held in position by RFs from two perpendicular suspended fibers. We develop a cortex–astral microtubule analytical model to capture the retraction fiber dependence of the metaphase plate rotations. We observe that reduced orientational stability, on single fibers, results in increased monopolar mitotic defects, while multipolar defects become dominant as the number of adhered fibers increases. We use a stochastic Monte Carlo simulation of centrosome, chromosome, and membrane interactions to explain the relationship between the observed propensity of monopolar and multipolar defects and the geometry of RFs. Overall, we establish that while bipolar mitosis is robust in fibrous environments, the nature of division errors in fibrous microenvironments is governed by interphase cell shapes and adhesion geometries.
  • Thumbnail Image
    Quantitative Biophysical Metrics for Rapid Evaluation of Ovarian Cancer Metastatic Potential
    Mukherjee, Apratim; Zhang, Haonan; Ladner, Katherine; Brown, Megan; Urbanski, Jacob; Grieco, Joseph P.; Kapania, Rakesh K.; Lou, Emil; Behkam, Bahareh; Schmelz, Eva M.; Nain, Amrinder S. (American Society for Cell Biology, 2022-05-15)
    Ovarian cancer is routinely diagnosed long after the disease has metastasized through the fibrous sub-mesothelium. Despite extensive research in the field linking ovarian cancer progression to increasingly poor prognosis, there are currently no validated cellular markers or hallmarks of ovarian cancer that can predict metastatic potential. To discern disease progression across a syngeneic mouse ovarian cancer progression model, here, we fabricated extracellular-matrix mimicking suspended fiber networks: crosshatches of mismatch diameters for studying protrusion dynamics, aligned same diameter networks of varying inter-fiber spacing for studying migration, and aligned nanonets for measuring cell forces. We found that migration correlated with disease, while force-disease biphasic relationship exhibited f-actin stress-fiber network dependence. However, unique to suspended fibers, coiling occurring at tips of protrusions and not the length or breadth of protrusions displayed strongest correlation with metastatic potential. To confirm that our findings were more broadly applicable beyond the mouse model, we repeated our studies in human ovarian cancer cell lines and found that the biophysical trends were consistent with our mouse model results. Altogether, we report complementary high throughput and high content biophysical metrics capable of identifying ovarian cancer metastatic potential on time scale of hours.
  • Thumbnail Image
    Spatial-Temporal Pattern of Agricultural Total Factor Productivity Change (Tfpch) in China and Its Implications for Agricultural Sustainable Development
    Zhang, Haonan; Chen, Zheng; Wang, Jieyong; Wang, Haitao; Zhang, Yingwen (MDPI, 2023-03-21)
    With increasing tension between humans and land, and arising pressure on food security in China, the improvement of total factor productivity is important to realize agricultural modernization and promote rural revitalization strategy. In this study, we applied the DEA-Malmquist index method to measure the growth of China’s agricultural total factor productivity and its decomposition indexes at the prefecture-level city scale from 2011 to 2020. We found the average annual growth rate of agricultural total factor productivity was 4.5% during this period, with technical change being the driving factor and technical efficiency change being the suppressing factor. There is an initial decrease and then an increase in the Dagum Gini coefficient. The cold and hot spot areas of agricultural Tfpch were clearly formed. During the decade, the gravity center of agricultural Tfpch has migrated from the northeast to the southwest in general. Based on the characteristics of agricultural Tfpch, China is classified into four zones. In the future, the Chinese government should balance the government and the market mechanism, improve the agricultural science and technology innovation system and technology adoption promotion system, and implement classified policies to improve agriculture production efficiency.