Single-cell imaging is essential for elucidating the biological mechanism of cell function because it accurately reveals the heterogeneity among cells. The electrochemiluminescence (ECL) microscopy technique has been considered a powerful tool to study cells because of its high throughput and zero cellular background light. However, since cells are immobilized on the electrode surface, the steric hindrance and the insulation from the cells make it difficult to obtain a luminous cell ECL image. To solve this problem, direct ECL imaging of a single cell was investigated and achieved on chitosan and nano-TiO modified fluoride-doped tin oxide conductive glass (FTO/TiO/CS). The permeable chitosan film is not only favorable for cell immobilization but also increases the space between the bottom of cells and the electrode; thus, more ECL reagent can exist below the cells compared with the cells on a bare electrode, which guarantees the high sensitivity of quantitative analysis. The modification of nano-TiO strengthens the ECL visual signal in luminol solution and effectively improves the signal-to-noise ratio. The light intensity is correlated with the HO concentration on FTO/TiO/CS, which can be applied to analyze the HO released from cells at the single-cell level. As far as we know, this is the first work to achieve cell ECL imaging without the steric hindrance effect of the cell, and it expands the applications of a modified electrode in visualization study.
In
this work, a potential-resolved electrochemiluminescence (ECL)
method is developed and used for the apoptosis diagnosis at the single-cell
level. The apoptosis of cells usually induces the decreasing expression
of epidermal growth factor receptor (EGFR) and promotes phosphatidylserine
(PS) eversion on the cell membrane. Here, Au@L012 and g-C3N4 as ECL probes are functionalized with epidermal
growth factor (EGF) and peptide (PSBP) to recognize the EGFR and PS
on the cell surface, respectively, showing two well-separated ECL
signals during a potential scanning. Experimental results reveal that
the relative ECL change of g-C3N4 and Au@L012
correlates with the degree of apoptosis, which provides an accurate
way to investigate apoptosis without interference that solely changes
EGFR or PS. With a homemade ECL microscopy, we simultaneously evaluate
the EGFR and PS expression of abundant individual cells and, therefore,
achieve the visualization analysis of the apoptosis rate for normal
and cancer cell samples. This strategy contributes to visually studying
tumor markers and pushing the application of ECL imaging for the disease
diagnosis at the single-cell level.
In situ detection of the expression level of cell-surface receptors has become a hotspot study in recent years. We propose in this manuscript a novel strategy for sensitive electrochemiluminescence (ECL) detection of glucose transporter 4 (GLUT4) on human skeletal muscle cells (HSMCs). Graphene hydrogel (GH) was selected to fabricate a permeable electrode with the purpose of overcoming the steric hindrance of cells on electrode, which leads to errors in the detection of cell-surface receptors. GLUT4 was labeled with carbon dots (CDs), which generate ECL emission at the interface between GH and cells, so about half the amount of GLUT4 expressed at the cell surface could be determined, which provided an accurate GLUT4 expression quantification. The prepared cytosensor exhibited good analytical performance for HSMC cells, ranging from 500 to 1.0 × 10 6 cells•mL −1 , with a detection limit of 200 cells•mL −1 . The average amount of GLUT4 per HSMC cell was calculated to be 1.88 × 10 5 . Furthermore, GLUT4 on HSMC surface had a 2.3-fold increase under the action of insulin. This strategy is capable of evaluating the receptors on the cell surface, which may push the application of ECL for disease diagnosis.
The carbonization of pyridine is often observed in surface-enhanced Raman spectroscopy (SERS) measurements, while the potential ring-opening process and reaction mechanism remain elusive. In this paper, pyridine derivative cetylpyridinium chloride was chosen as a model molecule; its ring-opening process was captured and monitored through the technique of in situ SERS. The results show that if pyridyl and pyridyne are produced first, then the reaction route of m-pyridyl is m-Pyridyl →2,3and 3,4-Pyridyne →m-TS1 →m-IM1 →m-TS4 →m-IM3 (m-TS1, m-IM1, m-TS4, and m-IM3 are the products of m-pyridyl; IM: intermediate; TS: transition states), which perfectly matches the theoretically predicted lowest energy cost path and can be interpreted, as the surface plasmonic resonance of Au nanoparticles promoted the reaction. SERS and XPS measurements indicate that the reaction occurred at certain sites with the strongest enhanced electric field according to the Finite difference time domain calculation. These results prove the applicability of SERS in the in situ study of high-energy cost reaction and further expand its application in in situ detection of chemical reaction processes in general.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.