Fabrication and characterization of silicon nanostructures based on metal-assisted chemical etching

Wendong Zhang,Jie Hu,Xuge Fan,Shengbo Sang,Pengwei Li,Gang Li,Yongjiao Sun 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.1

We present a facile method to fabricate one-dimensional Si nanostructures based on Ag-induced selective etching of silicon wafers. To obtain evenly distributed Si nanowires (SiNWs), the fabrication parameters have been optimized. As a result, a maximum of average growth rate of 0.15 μm/min could be reached. Then, the fabricated samples were characterized by water contact angle (CA) experiments. As expected, the as-etched silicon samples exhibited a contact angle in the range of 132o-136.5o, whereas a higher contact angle (145o) could be obtained by chemical modification of the SiNWs with octadecyltrichlorosilane (OTS). Additionally, Raman spectra experiments have been carried out on as-prepared nanostructures, showing a typical decreasing from 520.9 cm−1 to 512.4 cm−1 and an asymmetric broadening, which might be associated with the phonon quantum confinement effect of Si nanostructures.

ZnO/NiO nanofibers prepared by electrostatic spinning for rapid ammonia detection at room temperature

Shiqiang Xu,Junhe Wang,Hongying Lin,Rongchao Li,Yongqiang Cheng,Shengbo Sang,Kai Zhuo 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.6

ZnO/NiO heterojunction nanofibers were synthesized by an electrostatic spinning technique in thiswork. The morphologies, crystal structures, and compositional features of the ZnO/NiO nanofiberswere analyzed by SEM, TEM, XRD, and EDS characterization. ZnO/NiO nanofibers with Zn contentsof 37.5 at% showed a 46% response to 300-ppm ammonia gas at room temperature (25 ± 1 ℃;56 ± 3% RH), with fast response and recovery behavior (100 s /25 s). The existence of p-n heterojunctionson the surface of ZnO/NiO nanofibers, as well as surface ionic conduction, improved the responseto ammonia gas in a synergistic manner.

Flexible and Highly Sensitive Piezoresistive Pressure Sensor with Sandpaper as a Mold

Wendan Jia,Qiang Zhang,Yongqiang Cheng,Dong Zhao,Yan Liu,Wendong Zhang,Shengbo Sang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.7

Flexible pressure sensors based on piezoresistive induction have recently become a research hotspot due to the simple device structure, low energy consumption, easy readout mechanism and excellent performance. For practical applications, flexible pressure sensors with both high sensitivity and low-cost mass production are highly desirable. Herein, this paper presents a high-sensitivity piezoresistive pressure sensor based on a micro-structured elastic electrode, which is low cost and can be mass-produced by a simple method of sandpaper molding. The microstructure of the electrode surface under external pressure causes a change in the effective contact area and the distance between the electrodes, which exhibits great pressure sensitivity. The test results show that the surface structure is twice as sensitive as the planar structure under low pressure conditions. This is because of the special morphology of silver nanowires (AgNWs), which exhibits the tip of nanostructures on the surface and realizes the quantum tunneling mechanism. The sensor has high sensitivity for transmitting signals in real time and it can also be used to detect various contact actions. The low cost mass production and high sensitivity of flexible pressure sensors pave the way for electronic skin, wearable healthcare monitors and contact inspection applications.

3D Bioprinted GelMA/PEGDA Hybrid Scaffold for Establishing an In Vitro Model of Melanoma

( Jiahui Duan ),( Yanyan Cao ),( Zhizhong Shen ),( Yongqiang Cheng ),( Zhuwei Ma ),( Lijing Wang ),( Yating Zhang ),( Yuchuan An ),( Shengbo Sang ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.4

Due to the high incidence of malignant melanoma, the establishment of in vitro models that recapitulate the tumor microenvironment is of great biological and clinical importance for tumor treatment and drug research. In this study, 3D printing technology was used to prepare GelMA/PEGDA composite scaffolds that mimic the microenvironment of human malignant melanoma cell (A375) growth and construct in vitro melanoma micro-models. The GelMA/PEGDA hybrid scaffold was tested by the mechanical property, cell live/dead assay, cell proliferation assay, cytoskeleton staining and drug loading assay. The growth of tumor cells in two- and three-dimensional culture systems and the anti-cancer effect of luteolin were evaluated using the live/dead staining method and the Cell Counting Kit-8 (CCK-8) method. The results showed a high aggregation of tumor cells on the 3D scaffold, which was suitable for long-term culture. Cytoskeleton staining and immunofluorescent protein staining were used to evaluate the degree of differentiation of tumor cells under 2D and 3D culture systems. The results indicated that 3D bioprinted scaffolds were more suitable for tumor cell expansion and differentiation, and the tumor cells were more aggressive. In addition, luteolin was time- and dose-dependent on tumor cells, and tumor cells in the 3D culture system were more resistant to the drug.

Preparation and In Vitro Characterization of Gelatin Methacrylate for Corneal Tissue Engineering

Yan Yayun,Cao Yanyan,Cheng Rong,Shen Zhizhong,Zhao Yajing,Zhang Yixia,Zhou Guohong,Sang Shengbo 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.1

BACKGROUND: Corneal disease is second only to cataract considered as the leading cause of blindness in the world, with high morbidity. Construction of corneal substitutes in vitro by tissue engineering technology to achieve corneal regeneration has become a research hotspot in recent years. We conducted in-depth research on the biocompatibility, physicochemical and mechanical properties of rat bone marrow mesenchymal stem cells (rBM-MSCs)-seeded gelatin methacrylate (GelMA) as a bioengineered cornea. METHODS: Four kinds of GelMA with different concentrations (7, 10, 15 and 30%) were prepared, and their physicchemical, optical properties, and biocompatibility with rBM-MSCs were characterized. MTT, live/dead staining, cell morphology, immunofluorescence staining and gene expression of keratocyte markers were performed. RESULTS: 7%GelMA hydrogel had higher equilibrium water content and porosity, better optical properties and hydrophilicity. In addition, it is more beneficial to the growth and proliferation of rBM-MSCs. However, the 30%GelMA hydrogel had the best mechanical properties, and could be more conducive to promote the differentiation of rBM-MSCs into keratocyte-like cells. CONCLUSION: As a natural biological scaffold, GelMA hydrogel has good biocompatibility. And it has the ability to promote the differentiation of rBM-MSCs into keratocyte-like cells, which laid a theoretical and experimental foundation for further tissue-engineered corneal stromal transplantation, and provided a new idea for the source of seeded cells in corneal tissue engineering.

A magnetostrictive self-powered biosensor based on Au-BaTiO3-FeGa & PDMS

Qiang Zhang,Meng Xu,Yan Liu,Chunyan Zhang,Rui Zhang,Zhiyuan Fu,Jianlong Ji,Riguang Zhang,Shengbo Sang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.117 No.-

Piezoelectric flexible sensors have been used to detect biomolecules such as sweat and glucose because oftheir passive, simple structure and high sensitivity. This paper proposes a novel flexible piezoelectric Au-BaTiO3-FeGa & PDMS biosensor in which magnetostrictive deformation amplifies the surface stress generatedby biomolecules combining on the thin film. The modification process of bovine serum albumin(BSA) binding with the sensor was initially determined by the first principles approach. Then, the sensingmechanism was verified by finite-element simulation. Based on the simulation results, flexible Au-BaTiO3-FeGa & PDMS biosensors were prepared, modified, and measured. The structure, modification,and detection of the sensors were analyzed by digital microscopy, Fourier transform infrared spectrometry(FTIR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The responses ofthe biosensors detecting different BSA solution concentrations under magnetic fields were then investigated. Experimental results indicate that the biosensor has the highest sensitivity under a magnetic fieldof 30 mT.