Transistor-based nanoelectronic sensors are capable of label-free real-time chemical and biological detection with high sensitivity and spatial resolution, although the short Debye screening length in high ionic strength solutions has made difficult applications relevant to physiological conditions. Here, we describe a new and general strategy to overcome this challenge for field-effect transistor (FET) sensors that involves incorporating a porous and biomolecule permeable polymer layer on the FET sensor. This polymer layer increases the effective screening length in the region immediately adjacent to the device surface, and thereby enables detection of biomolecules in high ionic strength solutions in real-time. Studies of silicon nanowire (SiNW) field-effect transistors (FETs) with additional polyethylene glycol (PEG) modification show that prostate specific antigen (PSA) can be readily detected in solutions with phosphate buffer (PB) concentrations as high as 150 mM, while similar devices without PEG modification only exhibit detectable signals for concentrations ≤ 10 mM. Concentration-dependent measurements exhibited real-time detection of PSA with a sensitivity of at least 10 nM in ~130 mM ionic strength PB with linear response up to the highest (1000 nM) PSA concentrations tested. The current work represents an important step toward general application of nanoelectronic detectors for biochemical sensing in physiological environments, and is expected to open up exciting opportunities for in-vitro and in-vivo biological sensing relevant to basic biology research through medicine.
Nanomaterial-based field-effect transistor (FET) sensors are capable of label-free real-time chemical and biological detection with high sensitivity and spatial resolution, although direct measurements in high-ionic-strength physiological solutions remain challenging due to the Debye screening effect. Recently, we demonstrated a general strategy to overcome this challenge by incorporating a biomoleculepermeable polymer layer on the surface of silicon nanowire FET sensors. The permeable polymer layer can increase the effective screening length immediately adjacent to the device surface and thereby enable real-time detection of biomolecules in high-ionic-strength solutions. Here, we describe studies demonstrating both the generality of this concept and application to specific protein detection using graphene FET sensors. Concentration-dependent measurements made with polyethylene glycol (PEG)-modified graphene devices exhibited real-time reversible detection of prostate specific antigen (PSA) from 1 to 1,000 nM in 100 mM phosphate buffer. In addition, comodification of graphene devices with PEG and DNA aptamers yielded specific irreversible binding and detection of PSA in pH 7.4 1x PBS solutions, whereas control experiments with proteins that do not bind to the aptamer showed smaller reversible signals. In addition, the active aptamer receptor of the modified graphene devices could be regenerated to yield multiuse selective PSA sensing under physiological conditions. The current work presents an important concept toward the application of nanomaterial-based FET sensors for biochemical sensing in physiological environments and thus could lead to powerful tools for basic research and healthcare.field-effect transistor | Debye screening | surface modification | DNA aptamer receptor | polyethylene glycol N anoelectronic biosensors offer broad capabilities for label-free high-sensitivity real-time detection of biological species that are important to both fundamental research and biomedical applications (1-6). In particular, field-effect transistor (FET) biosensors configured from semiconducting nanowires (1, 2), single-walled carbon nanotubes (1, 3, 4), and graphene (1, 5, 6) have been extensively investigated since the first report of real-time protein detection using silicon nanowire devices (7). Subsequent studies have demonstrated highly sensitive and in some cases multiplexed detection of key analytes, including protein disease markers (8-10), nucleic acids (11-13), and viruses (14), as well as detection of protein-protein interactions (8,(15)(16)(17) and enzymatic activity (8).The success achieved with nanomaterial-based FET biosensors has been limited primarily to measurements in relatively low-ionicstrength nonphysiological solutions due to the Debye screening length (18,19). In short, the screening length in physiological solutions, <1 nm, reduces the field produced by charged macromolecules at the FET surface and thus makes real-time label-free detection difficult. The first method reported to overcome this ...
This paper presents the experimental results and analyses on a controlled manipulation of liquid droplets upon local reduction and oxidation (redox) of a smart polymer-dodecylbenzenesulfonate doped polypyrrole (PPy(DBS)). The electrochemically tunable wetting property of PPy(DBS) permitted liquid droplet manipulation at very low voltages (-0.9 to 0.6 V). A dichloromethane (DCM) droplet was flattened upon PPy(DBS) reduction. It was found that the surface tension gradient across the droplet contact line induced Marangoni stress, which caused this deformation. Further observation of PPy(DBS)'s color change upon the redox process confirmed that the surface tension gradient was the driving force for the droplet shape change.
In this paper, a cell separation technique has been explored using antibody-functionalized Ni nanowires. An antibody (anti-CD31) against mouse endothelial cells (MS1) was conjugated to the Ni nanowire surface through self-assembled monolayers (SAMs) and chemical covalent reactions. The measured cytotoxicity was negligible on the CD-31 antibody-functionalized nanowires by the tetrazolium salt (MTT) assay. The use of functionalized nanowires for magnetically separating MS1 cells revealed that the cell separation yield was closely related to cell concentration and the nanowire/cell ratio. Cell separation yield using functionalized Ni nanowires was compared with that using commercial magnetic beads. Considering the volume difference of the material used between the beads and nanowires, antibody-functionalized nanowires showed an obvious advantage in cell separation. Further study on the effect of Ni nanowires on MS1 cells for extended culture confirmed that cell morphology remained comparable to control cells with a lower proliferation rate. This work demonstrates that antibody-functionalized Ni nanowires provide an effective means to separate target cells.
Positively charged Au NPs were preferably taken up by breast cancer cells. Combination of positive surface charge with mitochondria-targeting domain onto Au NPs allowed their accumulation in the mitochondria of breast cancer cells to significantly elevate reactive oxygen species formation in 5-aminolevulinic-acid-enabled photodynamic therapy and improve selective destruction of breast cancer cells.
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.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.