Enhancing and quenching luminescence with gold nanoparticle films: the influence of substrate on the luminescent properties

Diagnosis and prognosis of myocardial infarction on a plasmonic chip

Cardiovascular diseases lead to 31.5% of deaths globally, and particularly myocardial infarction (MI) results in 7.4 million deaths per year. Diagnosis of MI and monitoring for prognostic use are critical for clinical management and biomedical research, which require advanced tools with accuracy and speed. Herein, we developed a plasmonic gold nano-island (pGold) chip assay for diagnosis and monitoring of MI. On-chip microarray analysis of serum biomarkers (e.g., cardiac troponin I) afforded up to 130-fold enhancement of near-infrared fluorescence for ultra-sensitive and quantitative detection within controlled periods, using 10 μL of serum only. The pGold chip assay achieved MI diagnostic sensitivity of 100% and specificity of 95.54%, superior to the standard chemiluminescence immunoassay in cardiovascular clinics. Further, we monitored biomarker concentrations regarding percutaneous coronary intervention for prognostic purpose. Our work demonstrated a designed approach using plasmonic materials for enhanced diagnosis and monitoring for prognostic use towards point-of-care testing.

Plasmon-Enhanced Blue-Light Emission of Stable Perovskite Quantum Dot Membranes

A series of stable and color-tunable MAPbBr_3-xCl_x quantum dot membranes were fabricated via a cost-efficient high-throughput technology. MAPbBr_3-xCl_x quantum dots grown in-situ in polyvinylidene fluoride electrospun nanofibers exhibit extraordinary stability. As polyvinylidene fluoride can prevent the molecular group MA⁺ from aggregating, MAPbBr_3-xCl_x quantum dots are several nanometers and monodisperse in polyvinylidene fluoride fiber. As-prepared MAPbBr_3-xCl_x quantum dot membranes exhibit the variable luminous color by controlling the Cl^- content of MAPbBr_3-xCl_x quantum dots. To improve blue-light emission efficiency, we successfully introduced Ag nanoparticle nanofibers into MAPbBr_1.2Cl_1.8 quantum dot membranes via layer-by-layer electrospinning and obtained ~4.8 folds fluorescence enhancement for one unit. Furthermore, the originality explanation for the fluorescence enhancement of MAPbBr_3-xCl_x quantum dots is proposed based on simulating optical field distribution of the research system.

Plasmon-enhanced fluorescence imaging with silicon-based silver chips for protein and nucleic acid assay

Metal-enhanced fluorescence shows great potential for improving the sensitivity of fluoroscopy, which has been widely used in protein and nucleic acid detection for biosensor and bioassay applications. In comparison with the traditional glass-supported metal nanoparticles (MNPs), the introduction of a silicon substrate has been shown to provide an increased surface-enhanced Raman scattering (SERS) effect due to the coupling between the MNPs and the semiconducting silicon substrate. In this work, we further study the fluorescence-enhanced effect of the silicon-supported silver-island (Ag@Si) plasmonic chips. In particular, we investigate their practical application of improving the traditional immunoassay such as the biotin-streptavidin-based protein assay and the protein-/nucleic acid-labeled cell and tissue samples. The protein assay shows a wavelength-dependent enhancement effect of the Ag@Si chip, with an enhancement factor ranging from 1.2 (at 532 nm) to 57.3 (at 800 nm). Moreover, for the protein- and nucleic acid-labeled cell and tissue samples, the Ag@Si chip provides a fluorescence enhancement factor of 3.0-4.1 (at 800 nm) and a significant improvement in the signal/background ratio for the microscopy images. Such a ready accommodation of the fluorescence-enhanced effect for the immunoassay samples with simple manipulations indicates broad potential for applications of the Ag@Si chip not only in biological studies but also in the clinical field.