Flexible hyperspectral surface plasmon resonance microscopy

Aristolochic acids-hijacked p53 promotes liver cancer cell growth by inhibiting ferroptosis

Aristolochic acids (AAs) have been identified as a significant risk factor for hepatocellular carcinoma (HCC). Ferroptosis is a type of regulated cell death involved in the tumor development. In this study, we investigated the molecular mechanisms by which AAs enhanced the growth of HCC. By conducting bioinformatics and RNA-Seq analyses, we found that AAs were closely correlated with ferroptosis. The physical interaction between p53 and AAs in HepG2 cells was validated by bioinformatics analysis and SPR assays with the binding pocket sites containing Pro92, Arg174, Asp207, Phe212, and His214 of p53. Based on the binding pocket that interacts with AAs, we designed a mutant and performed RNA-Seq profiling. Interestingly, we found that the binding pocket was responsible for ferroptosis, GADD45A, NRF2, and SLC7A11. Functionally, the interaction disturbed the binding of p53 to the promoter of GADD45A or NRF2, attenuating the role of p53 in enhancing GADD45A and suppressing NRF2; the mutant did not exhibit the same effects. Consequently, this event down-regulated GADD45A and up-regulated NRF2, ultimately inhibiting ferroptosis, suggesting that AAs hijacked p53 to down-regulate GADD45A and up-regulate NRF2 in HepG2 cells. Thus, AAs treatment resulted in the inhibition of ferroptosis via the p53/GADD45A/NRF2/SLC7A11 axis, which led to the enhancement of tumor growth. In conclusion, AAs-hijacked p53 restrains ferroptosis through the GADD45A/NRF2/SLC7A11 axis to enhance tumor growth. Our findings provide an underlying mechanism by which AAs enhance HCC and new insights into p53 in liver cancer. Therapeutically, the oncogene NRF2 is a promising target for liver cancer.

Flexible Near-Infrared Plasmon-Polaritons in Epitaxial Scandium Nitride Enabled by van der Waals Heteroepitaxy

Van der Waals heteroepitaxy refers to the growth of strain- and misfit-dislocation-free epitaxial films on layered substrates or vice versa. Such heteroepitaxial technique can be utilized in developing flexible near-infrared transition metal nitride plasmonic materials to broaden their photonic and bioplasmonic applications, such as antifogging, smart windows, and bioimaging. Here, we show the first conclusive experimental demonstration of the van der Waals heteroepitaxy-enabled flexible semiconducting scandium nitride (ScN) thin films exhibiting near-infrared, low-loss epsilon-near-zero, and surface plasmon-polariton resonances. Deposited on fluorophlogopite-mica substrates with molecular beam epitaxy, polaritonic ScN heterostructures mark the first semiconducting nitride to exhibit plasmon resonance at the 1100-1250 nm spectral range, inside the biological transmission window. Interestingly, optical properties of such ScN exhibit remarkable stability even after bending more than 100 times. Creating low-cost and high-quality flexible yet refractory plasmonic ScN heterostructures for the near-infrared spectral range will advance flexible optics and bioplasmonic devices for practical applications.

Analysis of tissue-substrate adhesion by hyperspectral surface plasmon resonance microscopy

The preparation of histology slides is a critical step in histopathology, and poor-quality histology slides with weak adhesion of tissue sections to the substrate often affect diagnostic accuracy and sometimes lead to diagnostic failure due to tissue section detachment. This issue has been of concern and some methods have been proposed to enhance tissue-substrate adhesion. Unfortunately, quantitative analysis of the adhesion between tissue sections and glass slides is still challenging. In this work, the adhesion of mouse brain tissue sections on gold-coated glass slides was analyzed using a laboratory-fabricated hyperspectral surface plasmon resonance microscopy (HSPRM) system that enabled single-pixel spectral SPR sensing and provided two-dimensional (2D) distribution of resonance wavelengths (RWs). The existence of the nanoscale water gap between the tissue section and the substrate was verified by fitting the RW measured in each pixel using the five-layer Fresnel reflection model. In addition, a 2D image of the tissue-substrate adhesion distance (AD) was obtained from the measured 2D distribution of RWs. The results showed that tissue-substrate AD was 20-35 nm in deionized water and 4-24 nm in saline solution. The HSPRM system used in this work has a wide wavelength range of 400-1000 nm and can perform highly sensitive and label-free detection over a large dynamic detection range with high spectral and spatial resolutions, showing significant potential applications in stain-free tissue imaging, quantitative analysis of tissue-substrate adhesion, accurate identification of tumor cells, and rapid histopathological diagnosis.

Bright compact ultrabroadband source by orthogonal laser-sustained plasma

Laser-sustained plasma (LSP) source featuring high brightness and broadband spectral coverage is found to be powerful in various fields of scientific and industrial applications. However, the fundamental limit of low conversion efficiency constrains the system compactness and widespread applications of such broadband light sources. In this paper, we propose an innovative orthogonal LSP to break through the conversion efficiency limitation. Driven by the elevated conversion efficiency from absorbed laser power to ultraviolet (UV) emission, a compact broadband source (250-1650 nm) with UV spectral radiance exceeding 210 m W / ( m m 2 ⋅ s r ⋅ n m ) is achieved with >100 W pump laser. With the plot of a two-dimensional refractive index model, we report an important conceptual advance that the orthogonal design eliminates the influence of the negative lensing effect on laser power density. Experimental results unambiguously demonstrate that we achieve a bright compact UV-VIS-NIR source with negligible thermal loss and the highest conversion efficiency to our knowledge. Significant enhancement of 4 dB contrast-to-noise ratio (CNR) in spectral single-pixel imaging has been demonstrated using the proposed ultrabroadband source. By establishing the quantitative link between pumping optics design and plasma absorption, this work presents a compact broadband source that combines superior conversion efficiency and unprecedented brightness, which is essential to high-speed inspection and spectroscopy applications.

Nanoplasmonic Affinity Analysis System for Molecular Screening Based on Bright‐Field Imaging

Considering the improved detection of biological analytes for affinity analysis is highly desirable, a metasurface plasmon resonance (Meta‐SPR)‐based imaging system, incorporating a localized SPR sensing platform with different microfluidic systems and employing simple bright‐field imaging, is established in this study. This system enables low‐level analyte concentration analysis, ranging from 100 pm to 100 nm, with the real‐time removal of nonspecific binding signals within the same device field of view. Combined with microfluidic systems and microdroplet spotting, it is possible to automatically measure the kinetic curves of a sample at ten concentration gradients or detect the specific responses of multiple samples in a single experiment simultaneously. This system can inexpensively and conveniently achieve complex detection functions, demonstrating an innovative breakthrough in sensor detection.

Analysis of cellular response to drugs with a microfluidic single-cell platform based on hyperspectral imaging

BACKGROUND

Cellular response to pharmacological action of drugs is significant for drug development. Traditional detection method for cellular response to drugs normally rely on cell proliferation assay and metabolomics examination. In principle, these analytical methods often required cell labeling, invasion analysis, and hours of co-culture with drugs, which are relatively complex and time-consuming. Moreover, these methods can only indicate the drug effectiveness on cell colony rather than single cells. Thus, to meet the requirements of personal precision medicine, the development of drug response analysis on the high resolution of single cell is demanded.

RESULTS

To provide precise result for drug response on single-cell level, a microfluidic platform coupled with the label-free hyperspectral imaging was developed. With the help of horizontal single-cell trapping sieves, hundreds of single cells were trapped independently in microfluidic channels for the purposes of real-time drug delivery and single-cell hyperspectral image recording. To significantly identify the cellular hyperspectral change after drug stimulation, the differenced single-cell spectrum was proposed. Compared with the deep learning classification method based on hyperspectral images, an optimal performance can be achieved by the classification strategy based on differenced spectra. And the cellular response to different reagents, for example, K+, Epidermal Growth Factor (EGF), and Gefitinib at different concentrations can be accurately characterized by the differenced single-cell spectra analysis.

SIGNIFICANCE AND NOVELTY

The high-throughput, rapid analysis of cellular response to drugs at the single-cell level can be accurately performed by our platform. After systematically analyzing the materials and the structures of the single-cell microfluidic chip, the optimal single-cell trapping method was proposed to contribute to the further application of hyperspectral imaging on microfluidic single-cell analysis. And the hyperspectral characterization of single-cell with cancer drug stimulation proved the application potential of our method in personal cancer medication.

Surface plasmonic biosensors: principles, designs and applications

Recently, surface plasmon resonance (SPR) biosensors have been widely used in environmental monitoring, food contamination detection and diagnosing medical conditions due to their superior sensitivity, label-free detection and rapid analysis speed. This paper briefly elaborates on the development history of SPR technology and introduces SPR signal sensing principles. A summary of recent applications of SPR sensors in different fields is highlighted, including their figures of merit and limitations. Finally, the personal perspectives and future development trends about sensor preparation and design are discussed in detail, which may be critical for improving the performance of SPR sensors.