skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Enhanced Sensitivity and Homogeneity of SERS Signals on Plasmonic Substrate When Coupled to Paper Spray Ionization–Mass Spectrometry
Title: Enhanced Sensitivity and Homogeneity of SERS Signals on Plasmonic Substrate When Coupled to Paper Spray Ionization–Mass Spectrometry
This work reports on the development of an analyte sampling strategy on a plasmonic substrate to amplify the detection capability of a dual analytical system, paper spray ionization–mass spectrometry (PSI-MS) and surface-enhanced Raman spectroscopy (SERS). While simply applying only an analyte solution to the plasmonic paper results in a limited degree of SERS enhancement, the introduction of plasmonic gold nanoparticles (AuNPs) greatly improves the SERS signals without sacrificing PSI-MS sensitivity. It is initially revealed that the concentration of AuNPs and the type of analytes highly influence the SERS signals and their variations due to the “coffee ring effect” flow mechanism induced during sampling and the degree of the interfacial interactions (e.g., van der Waals, electrostatic, covalent) between the plasmonic substrate and analyte. Subsequent PSI treatment at high voltage conditions further impacts the overall SERS responses, where the signal sensitivity and homogeneity significantly increase throughout the entire substrate, suggesting the ready migration of adsorbed analytes regardless of their interfacial attractive forces. The PSI-induced notable SERS enhancements are presumably associated with creating unique conditions for local aggregation of the AuNPs to induce effective plasmonic couplings and hot spots (i.e., electromagnetic effect) and for repositioning analytes in close proximity to a plasmonic surface to increase polarizability (i.e., chemical effect). The optimized sampling and PSI conditions are also applicable to multi-analyte analysis by SERS and MS, with greatly enhanced detection capability and signal uniformity.  more » « less
Award ID(s):
2116612
PAR ID:
10561083
Author(s) / Creator(s):
; ; ; ;
Publisher / Repository:
MDPI
Date Published:
Journal Name:
Chemosensors
Volume:
12
Issue:
9
ISSN:
2227-9040
Page Range / eLocation ID:
175
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; (, SPIE)
    Miller, Benjamin L; Weiss, Sharon M; Danielli, Amos (Ed.)
    A paper-based biosensor integrating a functionalized porous silicon (PSi) membrane as the active sensing element for quantifiable protein detection has been developed. For similar short-time exposures to an analyte, improved molecular transport in PSi membranes when on paper leads to larger signal changes compared to traditional PSi films that remain on a silicon substrate. In this work, we discuss controlling the incubation time of the analyte and the overall testing time of the sensor by incorporating different combinations of wicking and absorbent paper beneath the PSi membrane. With this control, the PSi-on-paper sensor platform has the potential to serve as an effective low-cost rapid diagnostic test with highly sensitive, quantitative readout for a wide range of analytes. 
    more » « less
  2. ; ; ; ; ; (, RSC Advances)
    Surface-enhanced Raman spectroscopy (SERS) has great potential as an analytical technique for environmental analyses. In this study, we fabricated highly porous gold (Au) supraparticles ( i.e. , ∼100 μm diameter agglomerates of primary nano-sized particles) and evaluated their applicability as SERS substrates for the sensitive detection of environmental contaminants. Facile supraparticle fabrication was achieved by evaporating a droplet containing an Au and polystyrene (PS) nanoparticle mixture on a superamphiphobic nanofilament substrate. Porous Au supraparticles were obtained through the removal of the PS phase by calcination at 500 °C. The porosity of the Au supraparticles was readily adjusted by varying the volumetric ratios of Au and PS nanoparticles. Six environmental contaminants (malachite green isothiocyanate, rhodamine B, benzenethiol, atrazine, adenine, and gene segment) were successfully adsorbed to the porous Au supraparticles, and their distinct SERS spectra were obtained. The observed linear dependence of the characteristic Raman peak intensity for each environmental contaminant on its aqueous concentration reveals the quantitative SERS detection capability by porous Au supraparticles. The limit of detection (LOD) for the six environmental contaminants ranged from ∼10 nM to ∼10 μM, which depends on analyte affinity to the porous Au supraparticles and analyte intrinsic Raman cross-sections. The porous Au supraparticles enabled multiplex SERS detection and maintained comparable SERS detection sensitivity in wastewater influent. Overall, we envision that the Au supraparticles can potentially serve as practical and sensitive SERS devices for environmental analysis applications. 
    more » « less
  3. ; ; ; (, The Analyst)
    Bacterial cellulose nanocrystals (BCNCs) are biocompatible cellulose nanomaterials that can host guest nanoparticles to form hybrid nanocomposites with a wide range of applications. Herein, we report the synthesis of a hybrid nanocomposite that consists of plasmonic gold nanoparticles (AuNPs) and superparamagnetic iron oxide (Fe 3 O 4 ) nanoparticles supported on BCNCs. As a proof of concept, the hybrid nanocomposites were employed to isolate and detect malachite green isothiocyanate (MGITC) via magnetic separation and surface-enhanced Raman scattering (SERS). Different initial gold precursor (Au 3+ ) concentrations altered the size and morphology of the AuNPs formed on the nanocomposites. The use of 5 and 10 mM Au 3+ led to a heterogenous mix of spherical and nanoplate AuNPs with increased SERS enhancements, as compared to the more uniform AuNPs formed using 1 mM Au 3+ . Rapid and sensitive detection of MGITC at concentrations as low as 10 −10 M was achieved. The SERS intensity of the normalized Raman peak at 1175 cm −1 exhibited a log-linear relationship for MGITC concentrations between 2 × 10 −10 and 2 × 10 −5 M for Au@Fe 3 O 4 @BCNCs. These results suggest the potential of these hybrid nanocomposites for application in a broad range of analyte detection strategies. 
    more » « less
  4. ; ; ; ; ; (, Sensors and Actuators A: Physical)
    Plastic pollution is a major environmental and health threat due to its widespread presence in ecosystems and food chains. Despite extensive research on microplastics, the detection of submicron plastics remains challenging due to their distinct physical and chemical properties and the limitations of current analytical methods. SERS has attracted significant attention in recent research as an ultra-sensitive approach for detecting nanoplastics compared to other spectroscopy techniques. In this paper, a stable, biodegradable, waste-free novel paper-based SERS substrate is developed for the rapid detection of submicron (200 nm) polystyrene (PS) particles via the controlled deposition of AuNPs onto filter paper using an atmospheric cold plasma jet printing process. The density of AuNPs increases with the number of printing passes, correlating with enhanced SERS results. The resulting SERS substrates are capable of quantifying a broad range of PS concentrations (1–500 μg mL⁻¹) using just 5 μL of analyte. The fabricated SERS substrate enables reliable quantification of PS in water, exhibiting a strong linear correlation (R² = 0.993) between SERS intensity and PS concentration, with a detection limit of 10 μg mL⁻¹ . These substrates demonstrate exceptional stability and reproducibility over a 10-week period, addressing key challenges associated with paper-based SERS substrates and making them suitable for long-term monitoring. Furthermore, analysis of tap water as a representative real-world sample demonstrates the practical applicability of the SERS substrate for environmental monitoring, revealing quantifiable levels of PS contamination. 
    more » « less
  5. ; ; ; ; ; ; (, Advanced Optical Materials)
    Abstract Surface‐enhanced Raman scattering (SERS) sensing in microfluidic devices, namely optofluidic‐SERS, suffers an intrinsic tradeoff between mass transport and hot spot density, both of which are required for ultrasensitive detection. To overcome this compromise, photonic crystal‐enhanced plasmonic mesocapsules are synthesized, utilizing diatom biosilica decorated with in‐situ growth silver nanoparticles (Ag NPs). In the optofluidic‐SERS testing of this study, 100× higher enhancement factors and more than 1,000× better detection limit are achieved compared with traditional colloidal Ag NPs, the improvement of which is attributed to unique properties of the mesocapsules. First, the porous diatom biosilica frustules serve as carrier capsules for high density Ag NPs that form high density plasmonic hot‐spots. Second, the submicron‐pores embedded in the frustule walls not only create a large surface‐to‐volume ratio allowing for effective analyte capture, but also enhance the local optical field through the photonic crystal effect. Last, the mesocapsules provide effective mixing with analytes as they are flowing inside the microfluidic channel. The reported mesocapsules achieve single molecule detection of Rhodamine 6G in microfluidic devices and are further utilized to detect 1 × 10−9mof benzene and chlorobenzene compounds in tap water with near real‐time response, which successfully overcomes the constraint of traditional optofluidic sensing. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email