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Reducing energy consumption is one of the most effective ways to solve the problem of energy shortage. In this work, nature-inspired paint microgroove arrays with different periods were fabricated using a one-step laser ablation method. A wind tunnel experiment was performed at two wind speeds, 27.7 and 33.3 m/s, to collect drag force data on smooth and structured paint coatings. The results showed that microgroove arrays oriented perpendicular to the flow direction were beneficial to drag reduction, and a drag reduction rate of up to 7.2% was obtained. Meanwhile, the microgroove arrays induced by laser ablation changed the wettability of the paint surface to hydrophobicity. The contact angle shows a slightly decreasing trend with an increase in the periodic scale. Furthermore, the anticorrosion properties of these microgrooves make them advantageous in harsh environments. The fabricated drag-reducing paint microstructures, with the features of self-cleaning and durability, have the potential to be applied on vehicles to realize speed improvement and energy saving.

Currently, silver nanoparticles (AgNPs) are the most produced nanoparticles in global market and have been widely utilized in the biomedical field. Here, we investigated the morphological and mechanical effects of AgNPs on cancerous cells of A549 cells and SMMC-7721 cells with atomic force microscope (AFM). The influences of AgNPs on the morphological properties and mechanical properties of cancerous cells were characterized utilizing the force-volume (FV) mode and force spectroscopy (FS) mode of AFM measurement. We mainly focus on the comparison of the effects of AgNPs on the two types of cancerous cells based on the fitting results of calculating the Young's moduli based on Sneddon model. The results showed that the morphology changed little but the mechanical properties of height, roughness, adhesion force and Young's moduli of two cancerous cells varied significantly with the stimulation of different concentrations of AgNPs. This research has provide insights into the classification and characterization of the effects of the various concentrations of AgNPs on the cancerous cells in vitro by utilizing AFM methodologies for disease therapy. This article is protected by copyright. All rights reserved.

Osteosarcoma (OS) is a primary malignant bone tumor that occurs mainly in adolescents. Researchers are devoting to develop combination therapy methods in a multifunctional nanoplatform for the treatment of osteosarcoma. The results of previous research have shown that up-regulation of miR- 520a-3p could induce anticancer effects in osteosarcoma. In order to improve the effect of gene therapy (GT), we attempted to carry miR-520a-3p in a multifunctional vector for comprehensive therapy. Fe 2 O 3 is a type of magnetic resonance imaging contrast that is widely used as a drug delivery agent. When coated with polydopamine (PDA), it can also be used as a photothermal therapy (PTT) agent (Fe 2 O 3 @ PDA). To deliver nanoagents targeted to a tumor site, folic acid (FA) conjugated with Fe 2 O 3 @PDA was manufactured as FA-Fe 2 O 3 @PDA. FA was chosen as the target molecule to enhance utilization and reduce toxicity of nanoparticles. However, the therapeutic efficacy of FA-Fe 2 O 3 -PDA combined with miR-520a-3p has not yet been studied. In this study, we synthesized FA-Fe 2 O 3 @PDA-miRNA and investigated the potential of combining PDA regulated PTT and miR-520a-3p regulated GT to kill osteosarcoma cells. The results indicated that down-regulation of interleukin 6 receptor (IL6R) by miR- 520a-3p and the photothermal ability of PDA could induce satisfactory anticancer effects in osteosarcoma, and the curative ratio was better than that used alone PTT or GT. Moreover, as a kind of T 2 magnetic contrast, miRNA-Fe 2 O 3 @PDA-FA can be used for magnetic resonance imaging (MRI). These findings indicated that miRNA-Fe 2 O 3 @PDA-FA is an effective anti-tumor nanovector for PTT combined with GT.

Surface-enhanced Raman scattering (SERS) has attracted attention because of its enormous potential to detect molecules with low concentrations. The method of fabricating SERS substrates is of great importance for improving the detection resolution. However, SERS substrates with different triangular pyramid tips fabricated by using the tip-based nanoindentation method has not been reported. Here, we prepared arrayed micro/nanocavities on copper-based graphene using the continuous indentation method with a Berkovich tip and a cube-corner tip, which have different face angles. Gold nanoparticles were then sputtered onto the graphene-copper micro/nanocavities to form the Au@GR@Cu micro/nanocavities SERS substrates. The substrates formed using the Berkovich tip and cube-corner tip were labeled B2-B9 and C2-C9, respectively, in which the numbers indicate the machining feed. Rhodamine 6G (R6G) was employed, and the Raman intensities of R6G on the differently arrayed Au@GR@Cu micro/nanocavities were measured. The Raman intensities of R6G were stronger on the pile-ups than on the inverted triangular pyramid cavities. The Raman intensities of R6G were highest on the C2 and B2 structures and lowest on the C9 and B9 structures. The Raman intensities of R6G on the arrayed Au@GR@Cu micro/nanocavities fabricated by the cube-corner tip were stronger than those on the arrayed Au@GR@Cu micro/nanocavities fabricated using the Berkovich tip with the same machining feed. In addition, the electric field intensity and distribution of the B9 and C9 arrayed Au@GR@Cu were simulated using Comsol software. Au@GR@Cu structures fabricated by the cube-corner tip were generated with higher electric field intensities. Furthermore, the relative standard deviations at 1362 cm -1of R6G were 6.19 and 6.62% on the C2 and C4 surfaces, respectively, showing good homogeneity. The SERS spectra of 10 -9mol/L malachite green solution and 10 -6mol/L carbaryl solution were recognized on the C1, C2, and C4 surfaces on day 1 and after 3 months, respectively. After storage at room temperature for 3 months, the reductions in the Raman intensities were less than 10%, indicating excellent stability. The results showed that the arrayed Au@GR@Cu micro/nanocavities fabricated using the cube-corner tip performed better than those fabricated using the Berkovich tip and exhibited excellent uniformity, availability, and stability, providing great potential for detecting pesticides at low concentrations.

Chemically and biologically modified substrates for single-cell patterning have been studied extensively, but physically modified structures for single-cell patterning still need further study. In this paper, physically modified silicon nanostructures were introduced to study their effect on SHSY5Y cells. Double-beam double exposure laser interference lithography combined with metal-assisted etching (MACE) was used to fabricate the physically modified silicon nanostructures. It was found that the cells on the gratings stretched and grew orderly along the grating with a small cell area and almost the same cell length compared with those on the Si wafer (control group). While on the grids, the cells were round with limited spreading, grew independently and had the smallest cell area and cell length. Moreover, the localization ratio of cells adhered onto the areas of nanopillars in the grid structures with different periods has been investigated. The results suggest that the physically modified grid silicon nanostructures can regulate the single-cell localization growth and the rational design of substrate structures can maximize the single-cell localization ratio. The findings provide guidance for the design of physically modified nanostructures and regulating single cell patterning, and a better understanding of single-cell localized growth.

Hydrogen peroxide (H2O2), as a biomarker in a series of physiological processes, plays a crucial role in investigating the pathogenesis of some diseases. The highly sensitive and selective detection of H2O2 release from living cells has aroused tremendous research interests. Herein, a non-enzymatic electrochemical H2O2 biosensor was constructed based on AgPt bimetallic nanoparticle-structured MoS2 nanohybrid (AgPt/MoS2) as an electrocatalyst. The AgPt/MoS2 nanohybrid was successfully synthesized by a facile wet-chemical method. Compared with AgPt nanoparticles, the AgPt/MoS2 nanohybrid exhibited significant enhancement in catalytic performance towards H2O2. The main factor is that MoS2 nanosheets as a supporting material promote AgPt nanoparticles to expose more active sites. The electrochemical response of the AgPt/MoS2 hybrid-based biosensor to H2O2 was linear in the range of 20 μM-4 mM, and the detection limit was calculated as 1.0 μM. To prove practicality, the biosensor was further applied to detect H2O2 release from living SMMC-7721 cells. These results indicate the potential applications of the developed biosensor in monitoring physiological processes.

Cell viability detection plays a crucial role in apoptosis and anticancer drug research. Compared with conventional colorimetric assays and organic fluorescent probe-based imaging, it is greatly desired to develop a simple and facile fluorescent probe for in situ real-time detection of cell viability. Herein, MoS2 nanoflakes are employed as fluorescent probes for detecting cancer cell viability by using their inherent tunable photoluminescence (PL) properties by ion intercalation. The appropriate amount of MoS2 nanoflakes for A549 lung cancer cells was firstly determined by MTT assay. After MoS2 nanoflakes successfully covered cells, the effects of the nanoflakes on cell morphology and mechanical properties were studied by atomic force microscopy (AFM). Then, the modulation of PL by potassium ions (K+) from cells was investigated at different cell viabilities. The results showed that PL intensity increased as cell viability decreased. Finally, the nanoflakes were further used as fluorescent probes to assess the cell viability change induced by anticancer drugs. The results showed that with the increase of drug concentration, the fluorescence intensity increased, indicating a decrease in cell viability. The ion-modulated PL of MoS2 nanoflakes makes MoS2 a promising candidate for applications in anticancer drug screening.

Trypsin is playing an important role in the processes of cancer proliferation, invasion and metastasis which require the precise information of morphology and mechanical properties on the nano-scale for the related research. In this work, living human hepatoma (SMCC-7721) cells were treated with different concentrations of trypsin solution. The morphology and mechanical properties of the cells were measured via atomic force microscope (AFM). Statistical analyses of measurement data indicated that with the increase of trypsin concentration, the average cell height and the surface roughness were both increased, but the cell viability, the cell surface adhesion and the elasticity modulus were decreased significantly. The force required to puncture the cells was also gradually reduced. It indicates that trypsin not only hydrolyses the proteins between the cell and the substrate but also the membrane proteins. The results offer valuable clues for the cancerous process study, pathological analysis and trypsin inhibitor drug development. And this work provides an effective way for overcoming the cell membrane in drug injection for cell-targeted therapy.

In the past decades, many materials have been studied as carriers for targeted drug delivery. However, there is a need for utilizable and selective carrier materials with few side effects. Here, the magnetic Ganoderma Lucidum Spores (mGLS) as a highly efficient targeted drug delivery carrier were explored. Then the regulatable targeted drug delivery system was verified by loading and releasing of the 5-Fluorouracil (5-FU). The results showed that the maximum of the loaded 5-FU reached 250.23 mg·g−1 in the mGLS. The cumulative release of the 5-FU for the drug delivery system could reach 80.11% and 67.14% in the PBS and HCl after 48 h, respectively. In addition, this system showed the good pharmacokinetic properties in vivo. After 12 h, the blood concentration in the 5-FU@mGLS group kept at 5.3 µg·mL−1 and was four times higher than that in the 5-FU group. In summary, the GLS as a natural microscale core-shell structures appears the striking application in carrier material for oral drug delivery.

Cellular mechanical properties (CMPs) have been frequently reported as biomarkers for cell cancerization to assist objective cytology, compared to the current subjective method dependent on cytomorphology. However, single or dual CMPs cannot always successfully distinguish every kind of malignant cell from its benign counterpart. In this work, we extract 4 CMPs of four different graded bladder cancer (BC) cell lines by AFM (atomic force microscopy)-based nanoindentation to generate a CMP database, which is used to train a cancerization-grade classifier by machine learning. The classifier is tested on 4 categories of BC cells at different cancer grades. The classification shows split-independent robustness and an accuracy of 91.25% with an AUC-ROC (ROC stands for receiver operating characteristic, and ROC curve is a graphical plot which illustrates the performance of a binary classifier system as its discrimination threshold is varied) value of 97.98%. Finally, we also compare our proposed method with traditional invasive diagnosis and noninvasive cancer diagnosis relying on cytomorphology, in terms of accuracy, sensitivity and specificity. Unlike former studies focusing on the discrimination between normal and cancerous cells, our study fulfills the classification of 4 graded cell lines at different cancerization stages, and thus provides a potential method for early detection of cancerization. STATEMENT OF SIGNIFICANCE: We measured four cellular mechanical properties (CMPs) of 4 graded bladder cancer (BC) cell lines using AFM (atomic force microscopy). We found that single or dual CMPs cannot fulfill the task of BC cell classification. Instead, we employ MLA (Machine Learning Algorithm)-based analysis whose inputs are BC CMPs. Compared with traditional cytomorphology-based prognoses, the non-invasive method proposed in this study has higher accuracy but with many fewer cellular properties as inputs. The proposed non-invasive prognosis is characterized with high sensitivity and specificity, and thus provides a potential tumor-grading means to identify cancer cells with different metastatic potential. Moreover, our study proposes an objective grading method based on quantitative characteristics desirable for avoiding misdiagnosis induced by ambiguous subjectivity.

Graphene (G) and its derivatives are important nanomaterials with potential medical applications for biosensors and implanting biomaterials. The hydrophobicity and surface microstructures of substrates have great influences on the biological and physical properties of the surface-bound cells. In this work, we used the two-beam laser interference (TBLI) technique to prepare a two-dimensional (2-D) grating structure on the surface of graphene oxide (GO) film. We investigated the effect of GO and the GO film with the 2-D grating structure substrates on the growth behavior of rat brain microvascular endothelial (bEnd.3) cells. The results demonstrated that the cell spreading area and the number of surface-bound cells were closely related to the hydrophobicity of the substrate and the presence of oxygen-containing functional groups (OCGs). Due to the interaction of laser and GO, the GO in the interference area was transformed into reduced graphene oxide (RGO). The grating-structured GO film significantly affected the direction of cell spreading and morphology. It has a good application prospect as a scaffold in tissue engineering, and promising applications in the fields that require highly directional growth of cells, such as nerve injury repair, tendon repair and regeneration.

Macro-mechanical simulation software cannot easily simulate the atomic resolution of the tapping mode atomic force microscope (TM-AFM), so the accuracy of the corresponding mechanical model is questioned. In this paper, a TM-AFM simulation model is established using classical molecular dynamics (MD). The model simulated the tapping of gold (Au) and aluminum (Al) by probes with various amplitudes. The simulation yielded the z-direction force curves, trajectory curves and indentation curves of the probe. The amplitude change and the phase shift of the probe at various amplitudes were calculated from the direct measurement results. A contact jump and detachment jump become evident and are significant to energy and force results. The recovery ability of Al after indenting is smaller than that of Au. The energy calculations can be fitted to a high goodness of fit, reaching 0.99 and better; hence, the amplitude and phase shift variations of the probe can be used to fit the stored and dissipated energies, the sample energies when the sample is tapped. In this way, the TM-AFM is able to calculate the mechanical properties of the sample, and thus characterize the sample.

This study aims to study the effect of light size and intensity on photoconductive effect-based optically-induced dielectrophoresis (ODEP) for three-dimensional manipulation of cells. HL-7702 cells and SMMC-7721 cells in sucrose solution were manipulated three-dimensionally by ODEP. We found that the ODEP force generated by the three-dimensional non-uniform electric field will form a three-dimensional space, and the positive ODEP force will attract the cells near the space into it. When the number of cells is large, the three-dimensional stacking phenomenon will occur, that is, the three-dimensional assembly of cells. When the size of the light spot is similar to that of the cell, the projector with weak light intensity can only manipulate a single cell, while the laser with higher light intensity can carry out cell three-dimensional assembly. When the light intensity is similar, the larger size of light can produce larger a three-dimensional assembly space. So the cell three-dimensional manipulation by ODEP is achieved only when the photoconductive effect induced by the light pattern reaches the required intensity. The three-dimensional manipulation of cells by ODEP is from plane to stereo, and its realization is related to the light size and the photoconductive layer resistance determined by light intensity. And the three-dimensional space of assembling cells is related to the light size and intensity, and the larger and stronger the light, the larger the space.