Zewei Luo

Fiber Optic Surface Plasmon Resonance–Based Biosensor Technique: Fabrication, Advancement, and Application

ABSTRACT Fiber optic–based biosensors with surface plasmon resonance (SPR) technology are advanced label-free optical biosensing methods. They have brought tremendous progress in the sensing of various chemical and biological species. This review summarizes four sensing configurations (prism, grating, waveguide, and fiber optic) with two ways, attenuated total reflection (ATR) and diffraction, to excite the surface plasmons. Meanwhile, the designs of different probes (U-bent, tapered, and other probes) are also described. Finally, four major types of biosensors, immunosensor, DNA biosensor, enzyme biosensor, and living cell biosensor, are discussed in detail for their sensing principles and applications. Future prospects of fiber optic–based SPR sensor technology are discussed.

In situ targeting TEM8 via immune response and polypeptide recognition by wavelength-modulated surface plasmon resonance biosensor

There is an increasing interest in real-time and in situ monitoring of living cell activities in life science and medicine. This paper reports a whole cell sensing protocol over the interface of Au film coupled in a wavelength-modulated surface plasmon resonance (WMSPR) biosensor. With dual parabolic mirrors integrated in the sensor, the compact and miniaturized instrument shows satisfactory refractive index sensitivity (2220 nm/RIU) and a high resolution of resonance wavelength shift of 0.3 nm to liquid samples. The affinity interactions between the biomarker of human tumor endothelial marker 8 (TEM8) and antibody (Ab) or specific polypeptide (PEP) were firstly introduced to WMSPR biosensor analysis. Both the interaction events of Ab-cell and PEP-cell over the Au film interface can be recognized by the sensor and the balance time of interactions is about 20 min. The concentration range of Ab for quantitative monitoring of the TEM8 expression on human colon carcinoma SW620 cells was investigated. The present low-cost and time-saving method provides a time resolution of binding specificity between Ab/PEP and TEM8 for real-time analysis of antigen on living tumor cell surface.

Preparation and tumor cell model based biobehavioral evaluation of the nanocarrier system using partially reduced graphene oxide functionalized by surfactant.

Background Currently, surfactant-functionalized nanomaterials are tending toward development of novel tumor-targeted drug carriers to overcome multidrug resistance in cancer therapy. Now, investigating the biocompatibility and uptake mechanism of specific drug delivery systems is a growing trend, but usually a troublesome issue, in simple pharmaceutical research. Methods We first reported the partially reduced graphene oxide modified with poly(sodium 4-styrenesulfonate) (PSS) as a nanocarrier system. Then, the nanocarrier was characterized by atomic force microscope, scanning electron microscope, high-resolution transmission electron microscope, ultraviolet–visible (UV-vis) spectroscopy, Fourier transform infrared spectroscopy, X-Ray powder diffraction, and Raman spectroscopy. Epirubicin (EPI) was attached to PSSG via π–π stacking, hydrogen bonding, and physical absorption to form conjugates of PSSG–EPI. The adsorption and desorption profiles, cytotoxicity coupled with drug accumulation, and uptake of PSSG and PSSG–EPI were evaluated. Finally, the subcellular behaviors, distribution, and biological fate of the drug delivery system were explored by confocal laser scanning microscope using direct fluorescence colocalization imaging and transmission electron microscopy. Results The partially reduced graphene oxide sheets functionalized by surfactant exhibit good dispersibility. Moreover, due to much less carboxyl groups retained on the edge of PSSG sheets, the nanocarriers exhibit biocompatibility in vitro. The obtained PSSG shows a high drug-loading capacity of 2.22 mg/mg. The complexes of PSSG–EPI can be transferred to lysosomes in 2 hours through endocytosis, then the drug is released in the cytoplasm in 8 hours, and ultimately EPI is delivered into cell nucleus to exhibit medicinal effects in 1 day. Conclusion The comprehensive exploration of the biological uptake mechanism of functional graphene-mediated tumor cell targeting model provides a typical protocol for evaluation of drug delivery system and will benefit the discovery of new surfactant-modified nanocarriers in nanomedicine.

Investigation of biomarkers for discriminating breast cancer cell lines from normal mammary cell lines based on VOCs analysis and metabolomics

Many reports have focused on breath analysis of breast cancer patients. However, only a few studies have investigated biomarkers through volatile organic components (VOCs) analysis in vitro. The aim of this work is to investigate the volatile organic components fingerprint of human breast cancer cell lines and human normal mammary cells and explore potential VOCs biomarkers for noninvasive diagnosis of breast cancer. MCF-7, MDA-MB-231 and CCD-1095Sk cell lines were employed in this work. Five biological replicates of each cell type were prepared for analysis. Gas chromatography and mass spectrometry (GC-MS) combined with solid-phase microextraction (SPME) was used to detect the VOCs released from the target cell lines. AMDIS-Spectconnect and metabolomic analysis were performed to process the data. According to the results, each kind of cell line shows a unique chromatogram. By applying Principal Component Analysis (PCA), Partial Least Squares Data Analysis (PLS-DA), four components, including 2-ethyl-1-hexanol, 2,4-dimethyl-benzaldehyde, cyclohexanol and p-xylene, were found to be potential biomarkers for discriminating breast cancer cell lines of the HER negative subtype and normal mammary cell line. The combination of the four components was more appropriate for the clinical diagnosis of breast cancer. The study indicated that the VOC profiles of breast cancer cell lines and human normal mammary cell lines were quite different and the investigated biomarkers may hold promise for non-invasive diagnosis of breast cancer.

A Facile, Label-free and Universal Biosensor Platform Based on Target-induced Graphene Oxide Constrained DNA Dissociation Coupling with Improved Strand Displacement Amplification

In this work, we report a low-cost and easy operation biosensor platform capable of detection of various analytes with high sensitivity and good selectivity. By ingeniously assigning the specific aptamer into a primer-template integrated DNA template, and using monolayer graphene oxide as a reversible and nonspecific inhibitor, the simple biosensor platform is set up. Without a target, the DNA template is constrained by the graphene oxide sheet and results in low signal. In the presence of a target, the constrained DNA template is released from the graphene oxide surface via a target-induced aptamer conformational change, and further amplified through the improved strand displacement amplification reaction. Therefore, the target detection is simply converted to DNA detection, and a correlation between target concentration and fluorescence signal can be set up. As a result, dozens-fold signal enhancement, high sensitivity, good selectivity, and potential practicability are achieved in target detection. More importantly, the proposed biosensor platform is versatile, meaning that it can greatly facilitate the detection of a variety of analytes. Due to the low cost and easy availability of sensing materials, and the elimination of tedious detection operations, we believe that this simple and universal biosensor platform can find wide applications in biological assay and environment monitoring.