More Like this

1. Graphene/gold nanoparticle composites for ultrasensitive and versatile biomarker assay using single-particle inductively-coupled plasma/mass spectrometry

   https://doi.org/10.1039/d0an01019g  

   Xing, Yuqian; Han, Juan; Wu, Xu; Pierce, David T.; Zhao, Julia Xiaojun (January 2020, The Analyst)

   null (Ed.)

   An ultrasensitive and versatile assay for biomarkers has been developed using graphene/gold nanoparticles (AuNPs) composites and single-particle inductively-coupled plasma/mass spectrometry (spICP-MS). Thrombin was chosen as a model biomarker for this study. AuNPs modified with thrombin aptamers were first non-selectively adsorbed onto the surface of graphene oxide (GO) to form GO/AuNPs composites. In the presence of thrombin, the AuNPs desorbed from the GO/AuNPs composites due to a conformation change of the thrombin aptamer after binding with thrombin. The desorbed AuNPs were proportional to the concentration of thrombin and could be quantified by spICP-MS. By counting the individual AuNPs in the spICP-MS measurement, the concentration of thrombin could be determined. This assay achieved an ultralow detection limit of 4.5 fM with a broad linear range from 10 fM to 100 pM. The method also showed excellent selectivity and reproducibility when a complex protein matrix was evaluated. Furthermore, the diversity and ready availability of ssDNA ligands make this method a versatile new technique for ultrasensitive detection of a wide variety of biomarkers in clinical diagnostics. 

   more » « less
2. An integrated microfluidic platform for selective and real-time detection of thrombin biomarkers using a graphene FET

   https://doi.org/10.1039/D0AN00251H  

   Khan, Niazul I.; Mousazadehkasin, Mohammad; Ghosh, Sujoy; Tsavalas, John G.; Song, Edward (June 2020, The Analyst)

   null (Ed.)

   Lab-on-a-chip technology offers an ideal platform for low-cost, reliable, and easy-to-use diagnostics of key biomarkers needed for early screening of diseases and other health concerns. In this work, a graphene field-effect transistor (GFET) functionalized with target-binding aptamers is used as a biosensor for the detection of thrombin protein biomarker. Furthermore, this GFET is integrated with a microfluidic device for enhanced sensing performances in terms of detection limit, sensitivity, and continuous monitoring. Under this platform, a picomolar limit of detection was achieved for measuring thrombin; in our experiment measured as low as 2.6 pM. FTIR, Raman and UV-Vis spectroscopy measurements were performed to confirm the device functionalization steps. Based on the concentration-dependent calibration curve, a dissociation constant of K D = 375.8 pM was obtained. Continuous real-time measurements were also conducted under a constant gate voltage ( V GS ) to observe the transient response of the sensor when analyte was introduced to the device. The target selectivity of the sensor platform was evaluated and confirmed by challenging the GFET biosensor with various concentrations of lysozyme protein. The results suggest that this device technology has the potential to be used as a general diagnostic platform for measuring clinically relevant biomarkers for point-of-care applications. 

   more » « less
3. A click chemistry amplified nanopore assay for ultrasensitive quantification of HIV-1 p24 antigen in clinical samples

   https://doi.org/10.1038/s41467-022-34273-x  

   Wei, Xiaojun; Wang, Xiaoqin; Zhang, Zehui; Luo, Yuanyuan; Wang, Zixin; Xiong, Wen; Jain, Piyush K.; Monnier, John R.; Wang, Hui; Hu, Tony Y.; et al (November 2022, Nature Communications)

   Abstract Despite major advances in HIV testing, ultrasensitive detection of early infection remains challenging, especially for the viral capsid protein p24, which is an early virological biomarker of HIV-1 infection. Here, To improve p24 detection in patients missed by immunological tests that dominate the diagnostics market, we show a click chemistry amplified nanopore (CAN) assay for ultrasensitive quantitative detection. This strategy achieves a 20.8 fM (0.5 pg/ml) limit of detection for HIV-1 p24 antigen in human serum, demonstrating 20~100-fold higher analytical sensitivity than nanocluster-based immunoassays and clinically used enzyme-linked immunosorbent assay, respectively. Clinical validation of the CAN assay in a pilot cohort shows p24 quantification at ultra-low concentration range and correlation with CD4 count and viral load. We believe that this strategy can improve the utility of p24 antigen in detecting early infection and monitoring HIV progression and treatment efficacy, and also can be readily modified to detect other infectious diseases. 

   more » « less
4. Plasmonically Enhanced CRISPR/Cas13a‐Based Bioassay for Amplification‐Free Detection of Cancer‐Associated RNA

   https://doi.org/10.1002/adhm.202100956  

   Liu, Lin; Wang, Zheyu; Wang, Yixuan; Luan, Jingyi; Morrissey, Jeremiah_J; Naik, Rajesh_R; Singamaneni, Srikanth (August 2021, Advanced Healthcare Materials)

   Abstract Novel methods that enable sensitive, accurate and rapid detection of RNA would not only benefit fundamental biological studies but also serve as diagnostic tools for various pathological conditions, including bacterial and viral infections and cancer. Although highly sensitive, existing methods for RNA detection involve long turn‐around time and extensive capital equipment. Here, an ultrasensitive and amplification‐free RNA quantification method is demonstrated by integrating CRISPR‐Cas13a system with an ultrabright fluorescent nanolabel, plasmonic fluor. This plasmonically enhanced CRISPR‐powered assay exhibits nearly 1000‐fold lower limit‐of‐detection compared to conventional assay relying on enzymatic reporters. Using a xenograft tumor mouse model, it is demonstrated that this novel bioassay can be used for ultrasensitive and quantitative monitoring of cancer biomarker (lncRNA H19). The novel biodetection approach described here provides a rapid, ultrasensitive, and amplification‐free strategy that can be broadly employed for detection of various RNA biomarkers, even in resource‐limited settings. 

   more » « less
5. Characterization of nanoparticles used as precipitant agents for in situ upgrading of heavy crude oils via single particle inductively coupled plasma mass spectrometry (spICP-MS)

   https://doi.org/10.1016/j.fuel.2024.133452  

   Hebert, Deja; Salas-Ortiz, Yanila; Nelson, Jenny; Ovalles, Cesar; Lopez-Linares, Francisco; Rogel, Estrella; Poirier, Laura; Zito, Phoebe (February 2025, Fuel)

   The characterization of nanoparticles (NPs) in hydrocarbon matrices using single particle inductively coupled plasma mass spectrometry (spICP-MS) is underdeveloped. There are less than ten publications using spICP-MS in hydrocarbon matrices, and none have applied the technique to determine NP concentration and size distribution in asphaltenes after in-situ upgrading of heavy oils via solvent deasphalting. To our knowledge, no studies have used spICP-MS to track the nature of NP additives in the asphaltene fraction in hydrocarbons without adulteration of the sample. Particle number concentrations (PNC) derived from spICP-MS in hydrocarbon matrices are reported for the first time. Fe2O3 PNC increased by an order of magnitude, and NiO PNC increased 28 % compared to samples without additives, indicating that NPs were reasonably well-dispersed in the asphaltenes. Ionic concentrations were higher for Ni than Fe, which showed negligible changes in all samples. Here, we report the lowest size detection limits recorded for Fe2O3 NPs (32 nm ± 1 nm) using spICP-MS in hydrocarbon matrices. Further, NiO and Fe2O3 NP sizes matched the initial sizes added to the oil before precipitation, providing evidence that the nature of the NPs does not change after deasphaltation and subsequent mixing with asphaltenes. This study expands our understanding of the interactions between metal NPs and asphaltenes when used as co-precipitants during in situ upgrading of heavy crude oil. 

   more » « less