scholarly journals Designing Efficient Low-Cost Paper-Based Sensing Plasmonic Nanoplatforms

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3035 ◽  
Author(s):  
Laurentiu Susu ◽  
Andreea Campu ◽  
Ana Craciun ◽  
Adriana Vulpoi ◽  
Simion Astilean ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
High Sensitivity ◽  
Dark Field ◽  
Ease Of Use ◽  
Localized Surface Plasmon ◽  
Surface Enhanced Raman ◽  
Resonance Surface ◽  
Sensitivity Specificity ◽  
Plasmonic Paper

Paper-based platforms can be a promising choice as portable sensors due to their low-cost and facile fabrication, ease of use, high sensitivity, specificity and flexibility. By combining the qualities of these 3D platforms with the optical properties of gold nanoparticles, it is possible to create efficient nanodevices with desired biosensing functionalities. In this work, we propose a new plasmonic paper-based dual localized surface plasmon resonance–surface-enhanced Raman scattering (LSPR-SERS) nanoplatform with improved detection abilities in terms of high sensitivity, uniformity and reproducibility. Specifically, colloidal gold nanorods (GNRs) with a well-controlled plasmonic response were firstly synthesized and validated as efficient dual LSPR-SERS nanosensors in solution using the p-aminothiophenol (p-ATP) analyte. GNRs were then efficiently immobilized onto the paper via the immersion approach, thus obtaining plasmonic nanoplatforms with a modulated LSPR response. The successful deposition of the nanoparticles onto the cellulose fibers was confirmed by LSPR measurements, which demonstrate the preserved plasmonic response after immobilization, as well as by dark-field microscopy and scanning electron microscopy investigations, which confirm their uniform distribution. Finally, a limit of detection for p-ATP as low as 10−12 M has been achieved by our developed SERS-based paper nanoplatform, proving that our optimized plasmonic paper-based biosensing design could be further considered as an excellent candidate for miniaturized biomedical applications.

scholarly journals Nanozyme Applications: A Glimpse of Insight in Food Safety

2021 ◽  
Vol 9 ◽  
Author(s):  
Long Wu ◽  
Shuhong Zhou ◽  
Gonglei Wang ◽  
Yonghuan Yun ◽  
Guozhen Liu ◽  
...  
Keyword(s):  
Low Cost ◽  
Analytical Techniques ◽  
High Sensitivity ◽  
Food Contaminants ◽  
Electrochemical Assay ◽  
Enzyme Mimicking ◽  
Surface Enhanced Raman ◽  
Food Applications ◽  
Enhanced Raman Scattering ◽  
Sensitivity Specificity

Nanozymes own striking merits, including high enzyme-mimicking activity, good stability, and low cost. Due to the powerful and distinguished functions, nanozymes exhibit widespread applications in the field of biosensing and immunoassay, attracting researchers in various fields to design and engineer nanozymes. Recently, nanozymes have been innovatively used to bridge nanotechnology with analytical techniques to achieve the high sensitivity, specificity, and reproducibility. However, the applications of nanozymes in food applications are seldom reviewed. In this review, we summarize several typical nanozymes and provide a comprehensive description of the history, principles, designs, and applications of nanozyme-based analytical techniques in food contaminants detection. Based on engineering and modification of nanozymes, the food contaminants are classified and then discussed in detail via discriminating the roles of nanozymes in various analytical methods, including fluorescence, colorimetric and electrochemical assay, surface-enhanced Raman scattering, magnetic relaxing sensing, and electrochemiluminescence. Further, representative examples of nanozymes-based methods are highlighted for contaminants analysis and inhibition. Finally, the current challenges and prospects of nanozymes are discussed.

scholarly journals SMILE Platform: An Innovative Microfluidic Approach for On-Chip Sample Manipulation and Analysis in Oral Cancer Diagnosis

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 885
Author(s):  
Sofia Zoupanou ◽  
Annalisa Volpe ◽  
Elisabetta Primiceri ◽  
Caterina Gaudiuso ◽  
Antonio Ancona ◽  
...  
Keyword(s):  
Oral Cancer ◽  
Low Cost ◽  
High Sensitivity ◽  
Ease Of Use ◽  
Early Screening ◽  
Chip Sample ◽  
Large Audience ◽  
On Chip ◽  
Sensitivity Specificity ◽  
Large Diffusion

Oral cancer belongs to the group of head and neck cancers, and, despite its large diffusion, it suffers from low consideration in terms of prevention and early diagnosis. The main objective of the SMILE platform is the development of a low-cost device for oral cancer early screening with features of high sensitivity, specificity, and ease of use, with the aim of reaching a large audience of possible users and realizing real prevention of the disease. To achieve this goal, we realized two microfluidic devices exploiting low-cost materials and processes. They can be used in combination or alone to obtain on-chip sample preparation and/or detection of circulating tumor cells, selected as biomarkers of oral cancer. The realized devices are completely transparent with plug-and-play features, obtained thanks to a highly customized architecture which enables users to easily use them, with potential for a common use among physicians or dentists with minimal training.

Monolayer ZnS@Ag Nanospheres SERS Substrate for Highly Sensitive Dye Molecules Detection

NANO ◽  
2020 ◽  
Vol 15 (09) ◽  
pp. 2050122
Author(s):  
Chenyan Li ◽  
Chengxiang Yang ◽  
Weijun Li ◽  
Mingming Cheng ◽  
Yingkai Liu
Keyword(s):  
Self Assembly ◽  
Organic Dyes ◽  
Limit Of Detection ◽  
Low Cost ◽  
High Sensitivity ◽  
High Signal ◽  
Sers Substrate ◽  
Dye Molecules ◽  
Relative Standard ◽  
Surface Enhanced Raman

Surface-enhanced Raman scattering (SERS) substrates with low cost, high sensitivity and good reproducibility are still challenging in practical application. Herein, we propose a facile method to prepare monolayer ZnS@Ag nanospheres (NSs) by sputtering Ag nanoparticles (NPs) on the surfaces of the monolayer ZnS NSs produced by self-assembly. The monolayer ZnS@Ag NSs have rough surface and nanoscale gaps, which can produce large SERS effect. The dye molecules, Rhodamine 6G (R6G) and Rhodamine B (RhB), were used as probe to evaluate the SERS performance on the monolayer ZnS@Ag NSs. It was found that the monolayer ZnS@Ag NSs showed the high SERS sensitivity in the detection of R6G and RhB, the limit of detection (LOD) down to 9.12×10−13 M and 8.55×10−11 M, respectively. The corresponding enhancement factors (EF) are 3.01×108 and 8.2×106, respectively. Furthermore, the ordered structure makes the monolayer ZnS@Ag NSs substrate with high signal reproducibility and stability, and the relative standard deviation (RSD) values are less than 15%. Therefore, the monolayer ZnS@Ag NSs is a candidate for detecting organic dyes in the environment.

scholarly journals Direct-RT-qPCR Detection of SARS-CoV-2 without RNA Extraction as Part of a COVID-19 Testing Strategy: From Sample to Result in One Hour

Diagnostics ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 605 ◽  
Author(s):  
Eva Kriegova ◽  
Regina Fillerova ◽  
Petr Kvapil
Keyword(s):  
High Throughput Screening ◽  
High Speed ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Rna Extraction ◽  
Rna Isolation ◽  
High Sensitivity ◽  
Ease Of Use ◽  
Diagnostic Tools ◽  
Heat Inactivation

Due to the lack of protective immunity in the general population and the absence of effective antivirals and vaccines, the Coronavirus disease 2019 (COVID-19) pandemic continues in some countries, with local epicentres emerging in others. Due to the great demand for effective COVID-19 testing programmes to control the spread of the disease, we have suggested such a testing programme that includes a rapid RT-qPCR approach without RNA extraction. The Direct-One-Step-RT-qPCR (DIOS-RT-qPCR) assay detects severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in less than one hour while maintaining the high sensitivity and specificity required of diagnostic tools. This optimised protocol allows for the direct use of swab transfer media (14 μL) without the need for RNA extraction, achieving comparable sensitivity to the standard method that requires the time-consuming and costly step of RNA isolation. The limit of detection for DIOS-RT-qPCR was lower than seven copies/reaction, which translates to 550 virus copies/mL of swab. The speed, ease of use and low price of this assay make it suitable for high-throughput screening programmes. The use of fast enzymes allows RT-qPCR to be performed under standard laboratory conditions within one hour, making it a potential point-of-care solution on high-speed cycling instruments. This protocol also implements the heat inactivation of SARS-CoV-2 (75 °C for 10 min), which renders samples non-infectious, enabling testing in BSL-2 facilities. Moreover, we discuss the critical steps involved in developing tests for the rapid detection of COVID-19. Implementing rapid, easy, cost-effective methods can help control the worldwide spread of the COVID-19 infection.

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

2020 ◽  
Vol 13 (05) ◽  
pp. 2041004 ◽  
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.

scholarly journals Fluorescence Polarization Immunoassay for Determination of Enrofloxacin in Pork Liver and Chicken

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4462
Author(s):  
Xing Shen ◽  
Jiahong Chen ◽  
Shuwei Lv ◽  
Xiulan Sun ◽  
Boris B. Dzantiev ◽  
...  
Keyword(s):  
Fluorescence Polarization ◽  
Limit Of Detection ◽  
Polyclonal Antibodies ◽  
Screening Method ◽  
Sample Pretreatment ◽  
High Sensitivity ◽  
Cross Reactivity ◽  
Fluorescence Polarization Immunoassay ◽  
Pork Liver ◽  
Sensitivity Specificity

Enrofloxacin (ENR) is a widely used fluoroquinolone (FQ) antibiotic for antibacterial treatment of edible animal. In this study, a rapid and highly specific fluorescence polarization immunoassay (FPIA) was developed for monitoring ENR residues in animal foods. First, ENR was covalently coupled to bovine serum albumin (BSA) to produce specific polyclonal antibodies (pAbs). Three fluorescein-labeled ENR tracers (A, B, and C) with different spacers were synthesized and compared to obtain higher sensitivity. Tracer C with the longest arm showed the best sensitivity among the three tracers. The developed FPIA method showed an IC50 (50% inhibitory concentration) of 21.49 ng·mL−1 with a dynamic working range (IC20–IC80) of 4.30–107.46 ng·mL−1 and a limit of detection (LOD, IC10) of 1.68 ng·mL−1. The cross-reactivity (CR) of several structurally related compounds was less than 2%. The recoveries of spiked pork liver and chicken samples varied from 91.3% to 112.9%, and the average coefficients of variation were less than 3.83% and 5.13%, respectively. The immunoassay took only 8 min excluding sample pretreatment. This indicated that the established method had high sensitivity, specificity, and the advantages of simplicity. Therefore, the proposed FPIA provided a useful screening method for the rapid detection of ENR residues in pork liver and chicken.

scholarly journals Recyclable SERS-Based Immunoassay Guided by Photocatalytic Performance of Fe3O4@TiO2@Au Nanocomposites

Biosensors ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 25 ◽  
Author(s):  
Yuanyuan Du ◽  
Hongmei Liu ◽  
Yiran Tian ◽  
Chenjie Gu ◽  
Ziqi Zhao ◽  
...  
Keyword(s):  
Photocatalytic Performance ◽  
Limit Of Detection ◽  
Specific Antigen ◽  
High Sensitivity ◽  
Shell Nanoparticles ◽  
Sem Images ◽  
Potential Measurement ◽  
Surface Enhanced Raman ◽  
Clinical Measurements ◽  
Core Shell Nanoparticles

A novel recyclable surface-enhanced Raman scattering (SERS)-based immunoassay was demonstrated and exhibited extremely high sensitivity toward prostate specific antigen (PSA). The immunoassay, which possessed a sandwich structure, was constructed of multifunctional Fe3O4@TiO2@Au nanocomposites as immune probe and Ag-coated sandpaper as immune substrate. First, by adjusting the density of outside Au seeds on Fe3O4@TiO2 core-shell nanoparticles (NPs), the structure-dependent SERS and photocatalytic performance of the samples was explored by monitoring and degradating 4-mercaptobenzonic acid (4MBA). Afterwards, the SERS enhancement capability of Ag-coated sandpaper with different meshes was investigated, and a limit of detection (LOD), as low as 0.014 mM, was achieved by utilizing the substrate. Subsequently, the recyclable feasibility of PSA detection was approved by zeta potential measurement, absorption spectra, and SEM images and, particularly, more than 80% of SERS intensity still existed after even six cycles of immunoassay. The ultralow LOD of the recyclable immunoassay was finally calculated to be 1.871 pg/mL. Therefore, the recyclable SERS-based immunoassay exhibits good application prospects for diagnosis of cancer in clinical measurements.

scholarly journals New traps for the capture of Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse) (Diptera: Culicidae) eggs and adults

2020 ◽  
Author(s):  
Karina Rossi da Silva ◽  
William Ribeiro da Silva ◽  
Bianca Piraccini Silva ◽  
Adriano Nobre Arcos ◽  
Francisco A. da Silva Ferreira ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Aedes Albopictus ◽  
High Efficiency ◽  
Low Cost ◽  
High Sensitivity ◽  
Ease Of Use ◽  
Monitoring And Control ◽  
Density Index ◽  
Egg Density ◽  
And Control

AbstractThe control of arboviruses carried by Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse) can be performed with tools that monitor and reduce the circulation of these vectors. Therefore, the efficiency of four types of traps in capturing A. aegypti and A. albopictus eggs and adults, with the biological product Vectobac WG®, was evaluated in the field. For this, 20 traps were installed in two locations, which were in the South (Londrina, Paraná) and North (Manaus, Amazonas) Regions of Brazil, from March to April 2017 and January to February 2018, respectively. The UELtrap-E and UELtrap-EA traps captured A. aegypti and A. albopictus eggs: 1703/1866 eggs in Londrina, and 10268/2149 eggs in Manaus, respectively, and presented high ovitraps positivity index (OPI) values (averages: 100%/100% in Londrina, and 100%/96% in Manaus, respectively); and high egg density index (EDI) values (averages: 68/75 in Londrina, and 411/89 in Manaus, respectively), so they had statistically superior efficiency to that of the CRtrap-E and CRtrap-EA traps in both regions, that captured less eggs and adults: 96/69 eggs in Londrina, and 1091/510 eggs in Manaus, respectively. Also presented lower OPI values (averages: 28%/4% in Londrina, and 88%/60% in Manaus, respectively); and lower EDI values (averages: 10.5/9 in Londrina, and 47/30 in Manaus, respectively). The capture ratios of Aedes adults in the UELtrap-EA and CRtrap-EA traps in Londrina and Manaus were 53.3%/29.5% and 0%/9.8%, respectively. UELtrap-E and UELtrap-EA can be adopted as efficient tools for Aedes monitoring due to their high sensitivity, low cost and ease of use.Author summaryAedes aegypti and Aedes albopictus are species of mosquitoes responsible for the transmission of several arboviruses that cause infections worldwide. However, there are still no effective and safe vaccines or medications to prevent or treat arboviruses transmitted by these vectors, except for yellow fever. Moreover, current methodologies for monitoring and controlling A. aegypti and A. albopictus are not fully effective, as evidenced by the increasing cases of the arbovirus transmitted by these mosquitoes or have incompatible costs with the socioeconomic conditions of a large number of people. Thus, the traps tested in this study can be used as more effective and economical tools for monitoring and controlling A. aegypti and A. albopictus, since they are made with low cost material and they showed high efficiency in the capture of eggs, evidenced by the high values of ovitraps positive index and eggs density index, besides that one of the models captured Aedes spp. adults in both regions where they were tested. Therefore, the traps have potential for reducing Aedes spp. eggs and adults in the environment and sensibility for determining the local infestation index, which can be reconciled with official government strategies for more accurate vector monitoring and control actions.

scholarly journals Cas12a-based on-site and rapid nucleic acid detection of African swine fever

2019 ◽  
Author(s):  
Jing Bai ◽  
Haosi Lin ◽  
Haojian Li ◽  
Yang Zhou ◽  
Junshan Liu ◽  
...  
Keyword(s):  
African Swine Fever Virus ◽  
Low Cost ◽  
African Swine Fever ◽  
Lateral Flow ◽  
Ease Of Use ◽  
Nucleic Acid Detection ◽  
Lateral Flow Strip ◽  
Trade Offs ◽  
Laboratory Facilities ◽  
Sensitivity Specificity

AbstractThe mortality rate of hemorrhagic African swine fever (ASF), which targets domestic pigs and is caused by African swine fever virus (ASFV), can reach 100%. ASF has been reported in 25 Chinese provinces since August 2018. There is no effective treatment or vaccine for it and the present molecular diagnosis technologies have trade-offs in sensitivity, specificity, cost and speed, and none of them cater perfectly to ASF control. Thus, a technology that overcomes the need for laboratory facilities, is relatively low cost, and rapidly and sensitively detects ASFV would be highly valuable. Here, we describe an RAA-Cas12a-based system that combines recombinase-aided amplification (RAA) and CRISPR/Cas12a for ASFV detection. The fluorescence intensity readout of this system detected ASFV p72 gene levels as low as 10 aM. For on-site ASFV detection, lateral-flow strip readout was introduced for the first time in the RAA-Cas12a based system (named CORDS, Cas12a-based On-site and Rapid Detection System). We used CORDS to detect target DNA highly specifically using the lateral-flow strip readout. CORDS could identify the p72 gene at femtomolar sensitivity in an hour at 37°C, and only requires an incubator. For ease of use, the regents of CORDS was lyophilized to three tubes and remained the same sensitivity when stored at 4 °C for at least 7 days. Thus, CORDS provides a rapid, sensitive and easily operable method for ASFV on-site detection. Lyophilized CORDS can withstand long-term transportation and storage, and is ready for field applications.

scholarly journals Detection of EGFR deletion using unique RepSeq technology

2019 ◽  
Author(s):  
Thuraiayah Vinayagamoorthy ◽  
Dahui Qin ◽  
Fei Ye ◽  
Minghao Zhong
Keyword(s):  
Internal Control ◽  
Sanger Sequencing ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Wild Type ◽  
Sequencing Technology ◽  
Sequencing Method ◽  
Exon 19 Deletion ◽  
Sensitivity Specificity ◽  
Generation Sequencing

AbstractWe are reporting a novel sequencing technology, RepSeq (Repetitive Sequence), that has high sensitivity, specificity and quick turn-around time. This new sequencing technology is developed by modifying traditional Sanger sequencing technology in several aspects. The first, a homopolymer tail is added to the PCR primer(s), which makes interpreting electropherograms a lot easier than that in traditional Sanger sequencing. The second, an indicator nucleotide is added at the 5’end of the homopolymer tail. In the presence of a deletion, the position of the indicator nucleotide in relation to the wild type confirms the deletion. At the same time, the indicator of the wild type serves as the internal control. Furthermore, the specific design of the PCR and/or sequencing primers will specifically enrich/select mutant alleles, which increases sensitivity and specificity significantly. Based on serial dilution studies, the analytical lower limit of detection was 1.47 copies. A total of 89 samples were tested for EGFR exon 19 deletion, of which 21 were normal blood samples and 68 were samples previously tested by either pyrosequencing or TruSeq Next Generation Sequencing Cancer Panel. There was 100 % concordance among all the samples tested. RepSeq technology has overcome the shortcomings of Sanger sequencing and offers an easy-to-use novel sequencing method for personalized precision medicine.

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