Numerous studies have determined that physical cues, especially the nanotopography of materials, play key roles in directing stem cell differentiation. However, most research on nanoarrays for stem ...cell fate regulation is based on nonbiodegradable materials, such as silicon wafers, TiO2, and poly(methyl methacrylate), which are rarely used as tissue engineering biomaterials. In this study, we prepared biodegradable polylactic acid (PLA) nanopillar arrays with different diameters but the same center-to-center distance using a series of anodic aluminum oxide nanowell arrays as templates. Human adipose-derived stem cells (hADSCs) were selected to investigate the effect of the diameter of PLA nanopillar arrays on stem cell differentiation. By culturing hADSCs without the assistance of any growth factors or osteogenic-induced media, the differentiation tendencies of hADSCs on the nanopillar arrays were assessed at the gene and protein levels. The assessment results suggested that the osteogenic differentiation of hADSCs can be driven by nanopillar arrays, especially by nanopillar arrays with a diameter of 200 nm. Moreover, an in vivo animal model of the samples demonstrated that PLA film with the 200 nm pillar array exhibits an improved ectopic osteogenic ability compared with the planar PLA film after 4 weeks of ectopic implantation. This study has provided a new variable to investigate in the interaction between stem cells and nanoarray structures, which will guide the bone regeneration clinical research field. This work paves the way for the utility of degradable biopolymer nanoarrays with specific geometrical and mechanical signals in biomedical applications, such as patches and strips for spine fusion, bone crack repair, and restoration of tooth enamel.
Detecting biomarkers is an efficient method to diagnose and monitor patients' stages. For more accurate diagnoses, continuously detecting and monitoring multiple biomarkers are needed. To achieve ...point-of-care testing (POCT) of multiple biomarkers, a smartphone biosensor system with the multi-testing-unit (SBSM) based on localized surface plasmon resonance (LSPR) integrated multi-channel microfluidics was presented. The SBSM could simultaneously record nine sensor units to achieve the detection of multiple biomarkers. Additional 72 sensor units were fabricated for further verification. Well-designed modularized attachments consist of a light source, lenses, a grating, a case, and a smartphone shell. The attachments can be well assembled and attached to a smartphone. The sensitivity of the SBSM was 161.0 nm/RIU, and the limit of detection (LoD) reached 4.2 U/mL for CA125 and 0.87 U/mL for CA15-3 through several clinical serum specimens testing on the SBSM. The testing results indicated that the SBSM was a useful tool for detecting multi-biomarkers. Comparing with the enzyme-linked immunosorbent assays (ELISA) results, the results from the SBSM were correlated and reliable. Meanwhile, the SBSM was convenient to operate without much professional skill. Therefore, the SBSM could become useful equipment for point-of-care testing due to its small size, multi-testing unit, usability, and customizable design.
To study the characteristics of transition metal dichalcogenides (TMDCs) in the THz regime, several kinds of terahertz modulators based on TMDCs were fabricated. The properties of these terahertz ...modulators were measured on a terahertz time-domain spectroscopy system. An 808-nm laser was used as the controller of the THz modulator. Briefly, as the power of the pumping laser increased, the amplitude of the transmission THz wave decreased. To explain these results, an analysis based on photoconductivity was presented. Additionally, the influence of the boundary defects was pointed out to give further explanation about the working mechanism of the TMDC-based THz modulator. Based on this analysis, most of the behavior of TMDCs in THz modulators could be understood.
Surface plasmon resonance sensors based on grating coupling exhibiting two resonant wavelengths are less observed because usually thick metal films are used. In this paper, we propose gold gratings ...on a gold film with two narrow reflection dips. One is sensitive to the refractive index (RI) of the cover media with a sensitivity of 720 nm/RIU. However, the other is sensitive to the RI of the substrate, and hence, it can be used as a reference dip. This self-referenced sensor significantly reduces the error contributions of the light intensity fluctuations and temperature variation. Moreover, the electric field is stronger with less decay length than that of gold gratings without gold film. Therefore, gold gratings with a gold film are more suitable to be a biosensor. Besides, we also investigate the structure parameters (the thickness of the gold film, the thickness and width of gold gratings, and the RI of the substrate) on the reflection spectra.
Self-powered photodetectors can convert light into electrical signals without external power input and are widely used in applications such as imaging, sensing, communication, and security. The most ...popular approach for constructing a self-powered photodetector is typically based on the fabrication of an asymmetric metal-semiconductor (MS) contact; however, this technique is seriously limited by the Fermi-level pinning effect. Here, we report a room-temperature photodetector based on multi-layer MoS
2
sandwiched between two separated asymmetric graphene contacts. Our photodetector was driven by the built-in electric field generated by a van der Waals (vdW) contact instead of the traditional MS contact. Operating under zero-bias voltage, the highest photoresponsivity of 0.63 A W
−1
and a specific detectivity of 7.71×10
12
Jones were achieved at a wavelength of 450 nm with 0.08 µW cm
−2
incident power intensity. Compared with devices using symmetric contacts, a high ON/OFF current ratio of approximately 1520 and a fast response time on the order of microseconds were also observed in our asymmetric graphene contact device. Our experimental results may open a novel way toward the realization of vdW contacts for the fabrication of self-powered photodetectors.
Tumour cell migration has an important impact on tumour metastasis. Magnetic manipulation is an ascendant method for guiding and patterning cells. Here, a unique miniaturized microfluidic chip ...integrating cell isolation and migration assay was designed to isolate and investigate cell migration. The chip was fabricated and composed of a magnet adapter, a polytetrafluoroethylene(PDMS) microfluidic chip and six magnetic rings. This device was used to isolate MCF-7 cells from MDA-MB-231-RFP cells and evaluate the effects of TGF-β on MCF-7 cells. First, the two cell types were mixed and incubated with magnetic beads modified with an anti-EpCAM antibody. Then, they were slowly introduced into the chip. MCF-7 cells bond to the magnetic beads in a ring-shaped pattern, while MDA-MB-231-RFP cells were washed away by PBS. Cell viability was examined during culturing in the micro-channel. The effects of TGF-β on MCF-7 cells were evaluated by migration distance and protein expression. The integrated method presented here is novel, low-cost and easy for performing cell isolation and migration assay. The method could be beneficial for developing microfluidic device applications for cancer metastasis research and could provide a new method for biological experimentation.
Nanoimprint technology is powerful for fabricating nanostructures in a large area. However, expensive equipment, high cost, and complex process conditions hinder the application of nano-imprinting ...technology. Therefore, double-layer self-priming nanoimprint technology was proposed to fabricate ordered metal nanostructures uniformly on 4-inch soft and hard substrates without the aid of expensive instruments. Different nanostructure (gratings, nanoholes and nanoparticles) and different materials (metal and MoS
) were patterned, which shows wide application of double-layer self-priming nanoimprint technology. Moreover, by a double-layer system, the width and the height of metal can be adjusted through the photoresist thickness and developing condition, which provide a programmable way to fabricate different nanostructures using a single mold. The double-layer self-priming nanoimprint method can be applied in poor condition without equipment and be programmable in nanostructure parameters using a single mold, which reduces the cost of instruments and molds.
Hexagonal tin disulfide (SnS
2
) films were deposited by plasma-enhanced chemical vapor deposition (PECVD) method combined with solid sources, in which SnCl
4
·5H
2
O and Na
2
S
2
O
3
were used as ...the tin and sulfur sources, respectively. Nano-sheet and nano-flower structure SnS
2
films were obtained under different experimental conditions. The nano-sheet SnS
2
films were built by irregular nanoplates with 400 ± 100 nm in length and 10 nm in thickness. And the nano-flower SnS
2
films consisted of uniform nano-flowers in size with the diameter being around 1 μm. The influence of different substrates, the annealing treatment and the substrate temperature on the crystal structure, surface morphology, chemical composition, and optical properties of the SnS
2
films were systemically discussed. The results show that the crystal structure and surface morphology have some differences in the films deposited on different substrates. After annealing treatment, the crystallinity of the SnS
2
films increases, and at the same time, the internal stress reduces. However, there is no change in the stress direction. The surface morphology of the films turns into nano-flower from nano-sheet when the substrate temperature increases. The corresponding optical band gaps of the films are 2.68, 2.86, and 2.95 eV, which all show significant blue shift mainly due to the quantum confinement effect.
The microstructure mold fabrication for PDMS microfluidic chip remains complex and time-consuming process requiring special equipment and protocols: photolithography and etching. Thus, a rapid and ...cost-effective method is highly needed. Comparing with the traditional microfluidic chip fabricating process based on the micro-electromechanical system (MEMS), this method is simple and easy to implement, and the whole fabrication process only requires 1-2 h. Different size of microstructure from 100 to 1000 μm was fabricated, and used to culture four kinds of breast cancer cell lines. Cell viability and morphology was assessed when they were cultured in the micro straight channels, micro square holes and the bonding PDMS-glass microfluidic chip. The experimental results indicate that the microfluidic chip is good and meet the experimental requirements. This method can greatly reduce the process time and cost of the microfluidic chip, and provide a simple and effective way for the structure design and in the field of biological microfabrications and microfluidic chips.
Localized surface plasmon resonance-based plasmonic biosensors are interesting candidates for the design of portable optical biosensor platforms owing to their integration, miniaturization, ...multiparameter, real-time, and label-free detection characteristics. Plasmonic biosensor arrays that have been combined with microfluidics have been developed herein to detect exosomes label-free. Gold nano-ellipsoid arrays were fabricated with low-cost anodic aluminum oxide thin films that act as shadow masks for evaporation of Au. The nano-ellipsoid arrays were integrated with a microfluidic chip to achieve multiparameter detection. The anti-CD63 antibody that is specific to the exosome transmembrane protein CD63 is modified on the surface of the nano-ellipsoids. Exosome samples were injected into the biosensor platform at different concentrations and detected successfully. The detection limit was 1 ng/mL. The proposed plasmonic biosensor array can be universally applicable for the detection of other biomarkers by simply changing the antibody on the surface of the Au nano-ellipsoids. Moreover, this biosensor platform is envisaged to be potentially useful in the development of low-cost plasmonic-based biosensors for biomarker detection and for the investigation of exosomes for noninvasive disease diagnoses.
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