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Towards rational design and optimization of near-field enhancement and spectral tunability of hybrid core-shell plasmonic nanoprobes
摘要： In biology, sensing is a major driver of discovery. A principal challenge is to create a palette of probes that offer near single-molecule sensitivity and simultaneously enable multiplexed sensing and imaging in the “tissue-transparent” near-infrared region. Surface-enhanced Raman scattering and metal-enhanced fluorescence have shown substantial promise in addressing this need. Here, we theorize a rational design and optimization strategy to generate nanostructured probes that combine distinct plasmonic materials sandwiching a dielectric layer in a multilayer core shell configuration. The lower energy resonance peak in this multi-resonant construct is found to be highly tunable from visible to the near-IR region. Such a configuration also allows substantially higher near-field enhancement, compared to a classical core-shell nanoparticle that possesses a single metallic shell, by exploiting the differential coupling between the two core-shell interfaces. Combining such structures in a dimer configuration, which remains largely unexplored at this time, offers significant opportunities not only for near-field enhancement but also for multiplexed sensing via the (otherwise unavailable) higher order resonance modes. Together, these theoretical calculations open the door for employing such hybrid multi-layered structures, which combine facile spectral tunability with ultrahigh sensitivity, for biomolecular sensing.
关键词： plasmonic nanoprobes,near-field enhancement,hybrid core-shell,biomolecular sensing,spectral tunability,multiplexed sensing
更新于2025-09-11 14:15:04
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Tracing of dye molecules in living plants through NaGdF4:Yb3+,Er3+ fluorescent nanoprobes
摘要： In this paper, we demonstrated trace of dye molecules in living plants. The NaGdF4:Yb3+,Er3+ nanoparticles probe was used to detect the rhodamine B(RhB) in bean sprout. It is found that the fluorescencedye can be efficiently imbibed during the growing process and the absorbance presented a position dependence effect, which was supported by the upconversion spectra and the fluorescent image characterization. In addition, the concentration of the residual RhB in bean sprout can be efficiently traced by the synthesized probe based on the fluorescent resonant energy transfer. Finally, the relation between the excitation power, concentration and the ratio of yellow to green emission are discussed in detail. These results can be helpful in understanding the RhB dye molecules absorbance process in vegetable growth and provide an efficient way to trace the residual dyes in vivo plant.
关键词： Upconversion nanoprobes,Rare-earth-doped materials,fluorescence,Biological sensing and sensors,luminescence
更新于2025-09-10 09:29:36
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In Nano, Volume 12, Issue 11
摘要： Nanoprobes have become critical components of the many near-field imaging techniques developed over the past decade. These tools are typically constructed by integrating nanostructures on the tip of an optical fiber, for example, by coating them with an ultrathin layer of metal; etching with plasmonic nanoantennas; or attaching them with a single gold nanorod, semiconductor nanowire, metal nanoparticle, or photonic crystal nanocavity. The optical resonances of these materials to be concentrated into a confined region, enable light illuminating samples with nanometer resolution. However, these nanostructures are usually made with noble metals or semiconductors that lack biocompatibility and can easily rupture cells when interfacing with them. In addition, their preparation often requires sophisticated nanofabrication processes and electrochemical reactions. To avoid these issues, Li et al. (DOI: 10.1021/acsnano.8b05235) created nanoprobes made of living cells. The researchers made these tools by inserting a tapered fiber light source into a mixture of yeast and Lactobacillus acidophilus cells. Using light the researchers captured a single yeast cell onto its tip. Light conducted through that cell acted as a subsequent trapping laser beam to secure a string of connected L. acidophilus cells on top of the yeast cell. Tests showed that these nanoprobes could be used for near-field scanning imaging with a subwavelength spatial resolution to illuminate leukemia cells stained with green fluorescent protein in blood. The nanoprobes also demonstrated flexibility and deformability, bending when they contacted cells instead of rupturing them. The authors suggest that these living nanoprobes could find relevant applications in biosensing and imaging.
关键词： nanoprobes,imaging,living cells,near-field imaging,biosensing
更新于2025-09-10 09:29:36
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SERS-Based Quantification of PSMA in Tissue Microarrays Allows Effective Stratification of Patients with Prostate Cancer
摘要： Prostate specific membrane antigen (PSMA), a type II membrane protein, is an attractive biomarker that has been validated clinically for the diagnosis of prostate cancer. In this study, we developed surface-enhanced Raman scattering (SERS) nanoprobes for PSMA detection and quantification at the single-cell level on prostate cancer cells. The cells were targeted employing SERS nanoprobes that consisted of gold nanostars functionalized with PSMA aptamer molecules. We were able to quantify picomolar concentrations of soluble PSMA protein and used the resulting calibration curve to estimate the expression of PSMA on the surface of the prostate cancer cell, LNCaP, at the single-cell level. Importantly, we employed these SERS tags to stratify prostate cancer patients by assessing PSMA expression in tissues contained in a prostate tissue microarray. The stratification results clearly correlated PSMA expression to recommended therapy groups, rendering the described method as an effective tool to aid in designing personalized therapeutic protocols. Benchmarking detection sensitivity against immunofluorescence staining and comparing stratification results obtained with the two methods allowed us to validate our novel approach against standard practices. On the basis of these results, we confirm the validity of PSMA as an effective biomarker for prostate cancer patient evaluation and propose SERS-based diagnostic techniques as integrative methods for the assessment of disease stage and the identification of effective therapeutic protocols.
关键词： aptamer,tissue microarray,surface-enhanced Raman scattering,PSMA,Prostate specific membrane antigen,SERS,nanoprobes,prostate cancer,biomarker,gold nanostars
更新于2025-09-04 15:30:14
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Visualization of Endogenous Hydrogen Sulfide in Living Cells based on Au Nanorods@Silica Enhanced Fluorescence
摘要： Hydrogen sulfide as a gas indicator molecule plays an important role in various human physiological processes. However, due to the high volatility and diffusivity of H2S in biological systems, it is very difficult to implement a precise assay for H2S detection. Compared with the destructive instrumental methods, assays based on fluorescence probes provide noninvasive and real-time detections of H2S in living cells. In this work, we presented a fluorescent nanoprobe based on dye-functionalized Au nanorods (NRs)@silica for sensitive and selective detection of H2S in vitro and living cells. With the metal enhanced fluorescence effect, the fluorescence turn-on and turn-off were controlled by the formation and disassembly of coordination compound between dyes and copper ions. Silica matrix was used to coat the Au NRs to prevent them from the biological cytotoxicity. The effects of the different distances between Au NRs and fluorophores on fluorescent enhancement were explored and approximately 5-fold fluorescence enhancement was obtained with a distance of 22 nm. A detection of limit of 17 nM was achieved. In addition, visualization of exogenous and endogenous H2S in living cells was validated.
关键词： nanoprobes,Au nanorods@silica,metal enhanced fluorescence,living cells,endogenous H2S
更新于2025-09-04 15:30:14
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Responsive Upconversion Nanoprobe for Background‐Free Hypochlorous Acid Detection and Bioimaging
摘要： Responsive nanoprobes play an important role in bioassay and bioimaging, early diagnosis of diseases and treatment monitoring. Herein, a upconversional nanoparticle (UCNP)-based nanoprobe, Ru@UCNPs, for specific sensing and imaging of hypochlorous acid (HOCl) is reported. This Ru@UCNP nanoprobe consists of two functional components, i.e., NaYF4:Yb, Tm UCNPs that can convert near infrared light-to-visible light as the energy donor, and a HOCl-responsive ruthenium(II) complex [Ru(bpy)2(DNCH-bpy)](PF6)2 (Ru-DNPH) as the energy acceptor and also the upconversion luminescence (UCL) quencher. Within this luminescence resonance energy transfer nanoprobe system, the UCL OFF–ON emission is triggered specifically by HOCl. This triggering reaction enables the detection of HOCl in aqueous solution and biological systems. As an example of applications, the Ru@UCNPs nanoprobe is loaded onto test papers for semiquantitative HOCl detection without any interference from the background fluorescence. The application of Ru@UCNPs for background-free detection and visualization of HOCl in cells and mice is successfully demonstrated. This research has thus shown that Ru@UCNPs is a selective HOCl-responsive nanoprobe, providing a new way to detect HOCl and a new strategy to develop novel nanoprobes for in situ detection of various biomarkers in cells and early diagnosis of animal diseases.
关键词： imaging,nanoprobes,paper-based test strips,bioassay and bioimaging,luminescence resonance energy transfer,selective HOCl detection and imaging
更新于2025-09-04 15:30:14