PfHRP2 detection using plasmonic optrodes: performance analysis

Abstract Background Early malaria diagnosis and its profiling require the development of new sensing platforms enabling rapid and early analysis of parasites in blood or saliva, aside the widespread rapid diagnostic tests (RDTs). Methods This study shows the performance of a cost-effective optical fiber-based solution to target the presence of Plasmodium falciparum histidine-rich protein 2 (PfHRP2). Unclad multimode optical fiber probes are coated with a thin gold film to excite Surface Plasmon Resonance (SPR) yielding high sensitivity to bio-interactions between targets and bioreceptors grafted on the metal surface. Results Their performances are presented in laboratory conditions using PBS spiked with growing concentrations of purified target proteins and within in vitro cultures. Two probe configurations are studied through label-free detection and amplification using secondary antibodies to show the possibility to lower the intrisic limit of detection. Conclusions As malaria hits millions of people worldwide, the improvement and multiplexing of this optical fiber technique can be of great interest, especially for a future purpose of using multiple receptors on the fiber surface or several coated-nanoparticles as amplifiers.

Download Full-text

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.

Download Full-text

Label-Free Split Aptamer Sensor for Femtomolar Detection of Dopamine by Means of Flexible Organic Electrochemical Transistors

Materials ◽

10.3390/ma13112577 ◽

2020 ◽

Vol 13 (11) ◽

pp. 2577 ◽

Cited By ~ 5

Author(s):

Yuanying Liang ◽

Ting Guo ◽

Lei Zhou ◽

Andreas Offenhäusser ◽

Dirk Mayer

Keyword(s):

Detection Limit ◽

Electrochemical Sensors ◽

Limit Of Detection ◽

High Sensitivity ◽

Label Free ◽

Dopamine Detection ◽

Electrochemical Transistor ◽

Sensitivity And Selectivity

The detection of chemical messenger molecules, such as neurotransmitters in nervous systems, demands high sensitivity to measure small variations, selectivity to eliminate interferences from analogues, and compliant devices to be minimally invasive to soft tissue. Here, an organic electrochemical transistor (OECT) embedded in a flexible polyimide substrate is utilized as transducer to realize a highly sensitive dopamine aptasensor. A split aptamer is tethered to a gold gate electrode and the analyte binding can be detected optionally either via an amperometric or a potentiometric transducer principle. The amperometric sensor can detect dopamine with a limit of detection of 1 μM, while the novel flexible OECT-based biosensor exhibits an ultralow detection limit down to the concentration of 0.5 fM, which is lower than all previously reported electrochemical sensors for dopamine detection. The low detection limit can be attributed to the intrinsic amplification properties of OECTs. Furthermore, a significant response to dopamine inputs among interfering analogues hallmarks the selective detection capabilities of this sensor. The high sensitivity and selectivity, as well as the flexible properties of the OECT-based aptasensor, are promising features for their integration in neuronal probes for the in vitro or in vivo detection of neurochemical signals.

Download Full-text

Porous Silicon-Based Aptasensors: The Next Generation of Label-Free Devices for Health Monitoring

Molecules ◽

10.3390/molecules24122216 ◽

2019 ◽

Vol 24 (12) ◽

pp. 2216 ◽

Cited By ~ 8

Author(s):

Monica Terracciano ◽

Ilaria Rea ◽

Nicola Borbone ◽

Rosalba Moretta ◽

Giorgia Oliviero ◽

...

Keyword(s):

Nucleic Acid ◽

Porous Silicon ◽

Limit Of Detection ◽

Combinatorial Libraries ◽

High Sensitivity ◽

Label Free ◽

Great Specificity ◽

Silicon Based ◽

Exponential Enrichment

Aptamers are artificial nucleic acid ligands identified and obtained from combinatorial libraries of synthetic nucleic acids through the in vitro process SELEX (systematic evolution of ligands by exponential enrichment). Aptamers are able to bind an ample range of non-nucleic acid targets with great specificity and affinity. Devices based on aptamers as bio-recognition elements open up a new generation of biosensors called aptasensors. This review focuses on some recent achievements in the design of advanced label-free optical aptasensors using porous silicon (PSi) as a transducer surface for the detection of pathogenic microorganisms and diagnostic molecules with high sensitivity, reliability and low limit of detection (LoD).

Download Full-text

Surface Plasmon Resonance Assay for Label-Free and Selective Detection of HIV-1 p24 Protein

Biosensors ◽

10.3390/bios11060180 ◽

2021 ◽

Vol 11 (6) ◽

pp. 180

Author(s):

Lucia Sarcina ◽

Giuseppe Felice Mangiatordi ◽

Fabrizio Torricelli ◽

Paolo Bollella ◽

Zahra Gounani ◽

...

Keyword(s):

Limit Of Detection ◽

Covalent Binding ◽

Hiv Infections ◽

Selectivity Ratio ◽

Selective Detection ◽

Label Free ◽

Self Assembled Monolayer ◽

Label Free Detection ◽

P24 Protein ◽

Hiv 1

The early detection of the human immunodeficiency virus (HIV) is of paramount importance to achieve efficient therapeutic treatment and limit the disease spreading. In this perspective, the assessment of biosensing assay for the HIV-1 p24 capsid protein plays a pivotal role in the timely and selective detection of HIV infections. In this study, multi-parameter-SPR has been used to develop a reliable and label-free detection method for HIV-1 p24 protein. Remarkably, both physical and chemical immobilization of mouse monoclonal antibodies against HIV-1 p24 on the SPR gold detecting surface have been characterized for the first time. The two immobilization techniques returned a capturing antibody surface coverage as high as (7.5 ± 0.3) × 1011 molecule/cm2 and (2.4 ± 0.6) × 1011 molecule/cm2, respectively. However, the covalent binding of the capturing antibodies through a mixed self-assembled monolayer (SAM) of alkanethiols led to a doubling of the p24 binding signal. Moreover, from the modeling of the dose-response curve, an equilibrium dissociation constant KD of 5.30 × 10−9 M was computed for the assay performed on the SAM modified surface compared to a much larger KD of 7.46 × 10−5 M extracted for the physisorbed antibodies. The chemically modified system was also characterized in terms of sensitivity and selectivity, reaching a limit of detection of (4.1 ± 0.5) nM and an unprecedented selectivity ratio of 0.02.

Download Full-text

Label-Free Electrochemical Biosensor Based on Au@MoS₂–PANI for Escherichia coli Detection

Chemosensors ◽

10.3390/chemosensors9030049 ◽

2021 ◽

Vol 9 (3) ◽

pp. 49

Author(s):

Pushap Raj ◽

Man Hwan Oh ◽

Kyudong Han ◽

Tae Yoon Lee

Keyword(s):

Escherichia Coli ◽

Bacterial Infections ◽

Limit Of Detection ◽

Bacterial Pathogens ◽

Cost Effective ◽

Covalent Immobilization ◽

Label Free ◽

Self Assembled Monolayer ◽

Detection Range ◽

Linear Detection

Bacterial infections have become a significant challenge in terms of public health, the food industry, and the environment. Therefore, it is necessary to address these challenges by developing a rapid, cost-effective, and easy-to-use biosensor for early diagnosis of bacterial pathogens. Herein, we developed a simple, label-free, and highly sensitive immunosensor based on electrochemical detection using the Au@MoS₂–PANI nanocomposite. The conductivity of the glassy carbon electrode is greatly enhanced using the Au@MoS₂–PANI nanocomposite and a self-assembled monolayer of mercaptopropionic acid on the gold nanoparticle surface was employed for the covalent immobilization of antibodies to minimize the nonspecific adsorption of bacterial pathogens on the electrode surface. The biosensor established a high selectivity and sensitivity with a low limit of detection of 10 CFU/mL, and detected Escherichia coli within 30 min. Moreover, the developed biosensor demonstrated a good linear detection range, practical utility in urine samples, and electrode regenerative studies.

Download Full-text

Y-shaped probe for convenient and label-free detection of microRNA-21 in vitro

Analytical Biochemistry ◽

10.1016/j.ab.2016.01.022 ◽

2016 ◽

Vol 499 ◽

pp. 8-14 ◽

Cited By ~ 13

Author(s):

Kui He ◽

Rong Liao ◽

Changqun Cai ◽

Caishuang Liang ◽

Chan Liu ◽

...

Keyword(s):

Label Free ◽

Label Free Detection

Download Full-text

Development of an Optical Fiber Sensor with a D-shaped Fiber Bragg Grating Integrated in a Loop-mirror Optical Fiber Laser as a High Sensitivity Refractometer

Communications in Physics ◽

10.15625/0868-3166/16014 ◽

2021 ◽

Vol 32 ◽

Author(s):

Binh Pham Thanh ◽

Thuy Van Nguyen ◽

Van Hoi Pham ◽

Huy Bui ◽

Thi Hong Cam Hoang ◽

...

Keyword(s):

Refractive Index ◽

Optical Fiber ◽

Fiber Laser ◽

Fiber Bragg Grating ◽

Limit Of Detection ◽

Optical Fiber Sensor ◽

High Sensitivity ◽

Optical Signal ◽

Bragg Grating ◽

Loop Mirror

In this paper, we report a new type of refractometer based on a D-shaped fiber Bragg grating (FBG) integrated in a loop-mirror optical fiber laser. This proposed sensor is used in wavelength interrogation method, in which the D-shaped FBG is applied as a refractive index (RI) sensing probe and a mirror to select mode of laser. The D-shaped FBG is prepared by the removal of a portion of the fiber cladding covering the FBG by means of side-polishing technique. The D-shaped FBG sensing probe integrated in a loop-mirror optical fiber laser with saturated pump technique, the characteristics of sensing signals have been improved to obtain stable intensity, narrower bandwidth and higher optical signal-to-noise ratio compare to normal reflection configuration. The limit of detection (LOD) of this sensor can be achieved to 2.95 x 10-4 RIU in the refractive index (RI) range of 1.42-1.44. Accordingly, we believe that the proposed refractometer has a huge potential for applications in biochemical-sensing technique.

Download Full-text

One-Dimensional Diffraction Grating of Poly(Methacrylic Acid) Brushes For The Rapid Label-Free Detection of Yersinia Pestis With a Reflective Laser System

10.21203/rs.3.rs-882579/v1 ◽

2021 ◽

Author(s):

Feng-Ping Lin ◽

Hui-Ling Hsu ◽

Hui-Chung Lin ◽

Hsin-Hsien Huang ◽

Chien-Hsing Lu ◽

...

Keyword(s):

Laser Beam ◽

Yersinia Pestis ◽

Methacrylic Acid ◽

Limit Of Detection ◽

Incident Angle ◽

Diffraction Effect ◽

Label Free ◽

Diffraction Intensity ◽

One Dimensional ◽

Label Free Detection

Abstract Background: Because of the low sensitivity of commercial products, development of a facile method to rapidly identify plague on-site remains highly attractive. Line arrays of poly(methacrylic acid) (PMAA) brushes were grafted using a photoresist template to fabricate one-dimensional diffraction gratings (DGs). The as-prepared samples first bound protein G to immobilize and orient the tails of the antibody of Yersinia pestis (abY). A laser beam was employed to analyze the 2D and 3D reflective signals of DGs at an incident angle of 45°. The abY-tailed PMAA DG possessed an optical feature with a characteristic diffraction effect along the SII, in which the projection of the laser beam on the plane of the DG chip was parallel to the strips, and ST configurations, in which they were perpendicular. A fluidic diffraction chip based on the abY-tailed PMMA DG was fabricated to examine the ability to detect Yersinia pestis along the ST configuration. Results: Upon flowing through the chip, Yersinia pestis was attached to the abY-tailed PMMA DG, which changed the diffraction intensity. The degree of the diffraction intensity exhibited a linear response to Yersinia pestis at concentrations from 102 to 107 CFU mL−1, and the limit of detection was 75 CFU mL−1, 1000 times lower than a commercial product (Alexter Bio-Detect Test). The diffractive sensor could selectively detect Yersinia pestis in spiked serum samples, with excellent standard deviation and recovery. Conclusion: Our platform provides a simple, label-free method for on-site plague diagnosis to prevent the highly rapid transmission of plague.

Download Full-text

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.

Download Full-text

Coupling multiplex pre-amplification and droplet digital PCR for longitudinal monitoring ofESR1andPIK3CAmutations from plasma cell-free DNA

10.1101/598847 ◽

2019 ◽

Author(s):

Huilan Yao ◽

Grant Wu ◽

Subhasree Das ◽

Crystal MacKenzie ◽

Hua Gao ◽

...

Keyword(s):

Limit Of Detection ◽

Hot Spot ◽

Metastatic Breast ◽

High Sensitivity ◽

Cost Effective ◽

Digital Pcr ◽

Cost Effective Method ◽

High Prevalence ◽

High Concordance ◽

Hotspot Mutations

AbstractHere we report on the development of a sensitive and cost-effective method to longitudinally trackESR1andPIK3CAmutations from cfDNA in patients with metastatic breast cancer (MBC) using a streamlined and de-centralized workflow. Hotspot mutations inESR1have been shown to cause resistance to aromatase inhibitor–based and anti-estrogenic therapies, whilePIK3CAmutations have high prevalence in MBC. As a result, their utility as circulating biomarkers to predict or monitor response in the clinical development of investigational compounds has been the focus of many studies. Six regions inESR1andPIK3CAgenes containing 20 hotspot mutations were pre-amplified, followed by optimized singleplex ddPCR assays to detect allele frequencies of individual mutations. Without pre-amplification, the limit of detection (LOD) and limit of linearity (LOL) of individual ddPCR assays were at 0.05-0.1% and 0.25% level, respectively. With pre-amplification, the LOD and LOL were slightly elevated at 0.1-0.25% and 0.25-0.5% levels, respectively. High concordance was achieved to the BEAMing assay (Sysmex Inostics) for mutation positive assays (r=0.98, P<0.0001). In conclusion, coupling pre-amplification and ddPCR assays allowed us for the detection of up to 20 hot spot mutations inESR1andPIK3CAwith high sensitivity and reproducibility.

Download Full-text