High sensitivity label-free detection of Fe3+ ion in aqueous solution using fluorescent MoS2 quantum dots

Magnetic and fluorescent-based sensors have demonstrated widely applications due to their easily recycle and quickly optical response. However, the complex synthesis and weaker function of these sensors limit their practical applications. Herein, an unmodified, magnetic-functionalized carbon dots-based fluorescent sensor has been developed for label-free detection of pH and Cu[Formula: see text] with high sensitivity. The sensors can not only reversibly quench and recover the fluorescence signals in response to the variation of surrounding environment including pH and Cu[Formula: see text], but also be used as a high-efficiency recyclable adsorbent for removing Cu[Formula: see text], Hg[Formula: see text], Cr[Formula: see text] and Pb[Formula: see text] from aqueous solution.

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H2O2-sensitive quantum dots for the label-free detection of glucose

Talanta ◽

10.1016/j.talanta.2010.06.005 ◽

2010 ◽

Vol 82 (3) ◽

pp. 997-1002 ◽

Cited By ~ 70

Author(s):

Mei Hu ◽

Jing Tian ◽

Hao-Ting Lu ◽

Li-Xing Weng ◽

Lian-Hui Wang

Keyword(s):

Quantum Dots ◽

Label Free ◽

Label Free Detection

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Photonic crystals: A platform for label-free and enhanced fluorescence biomolecular and cellular assays

MRS Proceedings ◽

10.1557/proc-1133-aa04-01 ◽

2008 ◽

Vol 1133 ◽

Author(s):

Brian T. Cunningham ◽

Leo Chan ◽

Patrick C. Mathias ◽

Nikhil Ganesh ◽

Sherine George ◽

...

Keyword(s):

Photonic Crystal ◽

Photonic Crystals ◽

High Throughput Screening ◽

High Sensitivity ◽

Excitation Wavelength ◽

Label Free ◽

Crystal Surfaces ◽

Enhanced Fluorescence ◽

Preferred Direction ◽

Label Free Detection

Abstract Photonic crystal surfaces represent a class of resonant optical structures that are capable of supporting high intensity electromagnetic standing waves with near-field and far-field properties that can be exploited for high sensitivity detection of biomolecules and cells. While modulation of the resonant wavelength of a photonic crystal by the dielectric permittivity of adsorbed biomaterials enables label-free detection, the resonance can also be tuned to coincide with the excitation wavelength of common fluorescent tags - including organic molecules and semiconductor quantum dots. Photonic crystals are also capable of efficiently channeling fluorescent emission into a preferred direction for enhanced extraction efficiency. Photonic crystals can be designed to support multiple resonant modes that can perform label free detection, enhanced fluorescence excitation, and enhanced fluorescence extraction simultaneously on the same device. Because photonic crystal surfaces may be inexpensively produced over large surface areas by nanoreplica molding processes, they can be incorporated into disposable labware for applications such as pharmaceutical high throughput screening. In this talk, the optical properties of surface photonic crystals will be reviewed and several applications will be described, including results from screening a 200,000-member chemical compound library for inhibitors of protein-DNA interactions, gene expression microarrays, and high sensitivity of protein biomarkers.

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Citric Acid Capped CdS Quantum Dots for Fluorescence Detection of Copper Ions (II) in Aqueous Solution

Nanomaterials ◽

10.3390/nano9010032 ◽

2018 ◽

Vol 9 (1) ◽

pp. 32 ◽

Cited By ~ 9

Author(s):

Zhezhe Wang ◽

Xuechun Xiao ◽

Tong Zou ◽

Yue Yang ◽

Xinxin Xing ◽

...

Keyword(s):

Aqueous Solution ◽

Quantum Dots ◽

Citric Acid ◽

Limit Of Detection ◽

Copper Ions ◽

High Sensitivity ◽

Fluorescence Sensor ◽

Cds Quantum Dots ◽

Detection Range ◽

Cds Qds

Citric acid capped CdS quantum dots (CA-CdS QDs), a new assembled fluorescent probe for copper ions (Cu2+), was synthesized successfully by a simple hydrothermal method. In this work, the fluorescence sensor for the detection of heavy and transition metal (HTM) ions has been extensively studied in aqueous solution. The results of the present study indicate that the obtained CA-CdS QDs could detect Cu2+ with high sensitivity and selectivity. It found that the existence of Cu2+ has a significant fluorescence quenching with a large red shifted (from greenish-yellow to yellowish-orange), but not in the presence of 17 other HTM ions. As a result, Cu2S, the energy level below the CdS conduction band, could be formed at the surface of the CA-CdS QDs and leads to the quenching of fluorescence of CA-CdS QDs. Under optimal conditions, the copper ions detection range using the synthesized fluorescence sensor was 1.0 × 10‒8 M to 5.0 × 10‒5 M and the limit of detection (LOD) is 9.2 × 10‒9 M. Besides, the as-synthesized CA-CdS QDs sensor exhibited good selectivity toward Cu2+ relative to other common metal ions. Thus, the CA-CdS QDs has potential applications for detecting Cu2+ in real water samples.

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One-step hydrothermal synthesis of down/up-conversion luminescence F-doped carbon quantum dots for label-free detection of Fe3+

Microchemical Journal ◽

10.1016/j.microc.2019.104217 ◽

2019 ◽

Vol 151 ◽

pp. 104217 ◽

Cited By ~ 4

Author(s):

Dan Hong ◽

Xiaoyan Deng ◽

Jiaman Liang ◽

Jiayu Li ◽

Yi Tao ◽

...

Keyword(s):

Quantum Dots ◽

Hydrothermal Synthesis ◽

Carbon Quantum Dots ◽

Label Free ◽

Label Free Detection ◽

One Step

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Rapid label-free SERS detection of foodborne pathogenic bacteria based on hafnium ditelluride-Au nanocomposites

Journal of Innovative Optical Health Sciences ◽

10.1142/s1793545820410047 ◽

2020 ◽

Vol 13 (05) ◽

pp. 2041004 ◽

Cited By ~ 1

Author(s):

Yang Li ◽

Yanxian Guo ◽

Binggang Ye ◽

Zhengfei Zhuang ◽

Peilin Lan ◽

...

Keyword(s):

Pathogenic Bacteria ◽

Limit Of Detection ◽

Principal Component ◽

High Sensitivity ◽

Chemical Mechanism ◽

Sers Substrate ◽

Label Free ◽

Label Free Detection ◽

Surface Enhanced Raman ◽

Foodborne Pathogenic Bacteria

Two-dimensional (2D) nanomaterials have captured an increasing attention in biophotonics owing to their excellent optical features. Herein, 2D hafnium ditelluride (HfTe[Formula: see text], a new member of transition metal tellurides, is exploited to support gold nanoparticles fabricating HfTe2-Au nanocomposites. The nanohybrids can serve as novel 2D surface-enhanced Raman scattering (SERS) substrate for the label-free detection of analyte with high sensitivity and reproducibility. Chemical mechanism originated from HfTe2 nanosheets and the electromagnetic enhancement induced by the hot spots on the nanohybrids may largely contribute to the superior SERS effect of HfTe2-Au nanocomposites. Finally, HfTe2-Au nanocomposites are utilized for the label-free SERS analysis of foodborne pathogenic bacteria, which realize the rapid and ultrasensitive Raman test of Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Salmonella with the limit of detection of 10 CFU/mL and the maximum Raman enhancement factor up to [Formula: see text]. Combined with principal component analysis, HfTe2-Au-based SERS analysis also completes the bacterial classification without extra treatment.

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Biogenic Quantum Dots for Sensitive, Label-Free Detection of Mercury Ions

ACS Applied Bio Materials ◽

10.1021/acsabm.9b00331 ◽

2019 ◽

Vol 2 (6) ◽

pp. 2661-2667 ◽

Cited By ~ 7

Author(s):

Li-Jiao Tian ◽

Yuan Min ◽

Xue-Meng Wang ◽

Jie-Jie Chen ◽

Wen-Wei Li ◽

...

Keyword(s):

Quantum Dots ◽

Label Free ◽

Mercury Ions ◽

Label Free Detection

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Single-Molecule Detection of DNA in a Nanochannel by High-Field Strength-Assisted Electrical Impedance Spectroscopy

Micromachines ◽

10.3390/mi10030189 ◽

2019 ◽

Vol 10 (3) ◽

pp. 189 ◽

Cited By ~ 1

Author(s):

Porpin Pungetmongkol ◽

Takatoki Yamamoto

Keyword(s):

Single Molecule ◽

High Intensity ◽

High Sensitivity ◽

Electrical Impedance Spectroscopy ◽

Random Coil ◽

Label Free ◽

Electrode Gap ◽

Label Free Detection ◽

Intensity Field ◽

Nanogap Electrodes

Many researchers have fabricated micro and nanofluidic devices incorporating optical, chemical, and electrical detection systems with the aim of achieving on-chip analysis of macromolecules. The present study demonstrates a label-free detection of DNA using a nanofluidic device based on impedance measurements that is both sensitive and simple to operate. Using this device, the electrophoresis and dielectrophoresis effect on DNA conformation and the length dependence were examined. A low alternating voltage was applied to the nanogap electrodes to generate a high intensity field (>0.5 MV/m) under non-faradaic conditions. In addition, a 100 nm thick gold electrode was completely embedded in the substrate to allow direct measurements of a solution containing the sample passing through the gap, without any surface modification required. The high intensity field in this device produced a dielectrophoretic force that stretched the DNA molecule across the electrode gap at a specific frequency, based on back and forth movements between the electrodes with the DNA in a random coil conformation. The characteristics of 100 bp, 500 bp, 1 kbp, 5 kbp, 10 kbp, and 48 kbp λ DNA associated with various conformations were quantitatively analyzed with high resolution (on the femtomolar level). The sensitivity of this system was found to be more than about 10 orders of magnitude higher than that obtained from conventional linear alternating current (AC) impedance for the analysis of bio-polymers. This new high-sensitivity process is expected to be advantageous with regard to the study of complex macromolecules and nanoparticles.

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The Localized Enhancement of Surface Plasmon Standing Waves Interacting With Single Nanoparticles

10.21203/rs.3.rs-254097/v1 ◽

2021 ◽

Author(s):

hongyao liu ◽

Xuqing Sun ◽

Xue Wang ◽

Fei Wang ◽

Chang Wang ◽

...

Keyword(s):

Surface Plasmon ◽

Electric Dipole ◽

Surrounding Medium ◽

Standing Waves ◽

High Sensitivity ◽

Detection Sensitivity ◽

Label Free ◽

Vertical Electric Dipole ◽

Lower Dielectric Constant ◽

Label Free Detection

Abstract Real-time, high-sensitivity, and label-free detection to single nanoparticles has been achieved via visualizing the interaction between surface plasmon polaritons (SPPs) and nanoparticles, which is widely applied to chemistry and biology. In this work, aiming to enhance the detection sensitivity to nanoparticles, we explore the interaction of SPP standing waves with single nanoparticles. Compared with SPPs, the inhomogeneous fields of SPP standing waves modulate charge distributions around the particle and excite different electric dipole modes that tailor localized enhancements. For nanoparticles situating at electric antinodes of SPP standing waves, a vertical electric dipole is excited and high-density charges are stimulated around nanoparticle-film nanocavities, leading to further increased localized enhancement. The localized enhancement experiences more increase with smaller particle size, lower dielectric constant of surrounding medium, and lower particle refractive index. Via tailoring the localized enhancement by SPP standing waves, the sensitivity of SPP microscopy can be improved, which would broaden its applications on nanotechnology, biomedicine, and environmental monitoring.

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Evaluation of Three Peptide Immobilization Techniques on a QCM Surface Related to Acetaldehyde Responses in the Gas Phase

Sensors ◽

10.3390/s18113942 ◽

2018 ◽

Vol 18 (11) ◽

pp. 3942 ◽

Cited By ~ 10

Author(s):

Tomasz Wasilewski ◽

Bartosz Szulczyński ◽

Wojciech Kamysz ◽

Jacek Gębicki ◽

Jacek Namieśnik

Keyword(s):

Spin Coating ◽

Olfactory Receptors ◽

High Sensitivity ◽

Dip Coating ◽

Label Free ◽

Optimal Method ◽

Spin Coating Method ◽

Whole Cells ◽

Label Free Detection ◽

Coating Method

The quartz-crystal microbalance is a sensitive and universal tool for measuring concentrations of various gases in the air. Biochemical functionalization of the QCM electrode allows a label-free detection of specific molecular interactions with high sensitivity and specificity. In addition, it enables a real-time determination of its kinetic rates and affinity constants. This makes QCM a versatile bioanalytical screening tool for various applications, with surface modifications ranging from the detection of single molecular monolayers to whole cells. Various types of biomaterials, including peptides mapping the binding sites of olfactory receptors, can be deposited as a sensitive element on the surface of the electrodes. One of key ways to ensure the sensitivity and accuracy of the sensor is provided by application of an optimal and repeatable method of immobilization. Therefore, effective sensors operation requires development of an optimal method of deposition. This paper reviews popular techniques (drop-casting, spin-coating, dip-coating) for coating peptides on piezoelectric crystals surface. Peptide (LEKKKKDC-NH2) derived from an aldehyde binding site in the HarmOBP7 protein was synthesized and used as a sensing material for the biosensor. The degree of deposition of the sensitive layer was monitoring by variations in the sensors frequency. The highest mass threshold for QCM measurements for peptides was approximately 16.43 µg·mm−2 for spin coating method. Developed sensor exhibited repeatable response to acetaldehyde. Moreover, responses to toluene was observed to evaluate sensors specificity. Calibration curves of the three sensors showed good determination coefficients (R2 > 0.99) for drop casting and dip coating and 0.97 for the spin-coating method. Sensors sensitivity vs. acetaldehyde were significantly higher for the dip-coating and drop-casting methods and lower for spin-coating one.

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