Highly Sensitive Amperometric Sensor Based on Laccase-Mimicking Metal-Based Hybrid Nanozymes for Adrenaline Analysis in Pharmaceuticals

Nanozymes are nanomaterials which exhibit artificial enzymatic activities and are considered as alternatives to natural enzymes. They are characterized by good catalytic activity and high stability, as well as ease and low cost of preparation. In this study, the mimetics of laccase or “nanolaccases” (NLacs) were synthesized by a simple method of chemical reduction of transition metal salts. The NLacs were tested for their catalytic activity in solution and on the electrode surface. The most effective NLacs, namely nAuCePt and nPtFe, were found to possess excellent laccase-like activities capable of oxidizing the endocrine hormone adrenaline (AD). These NLacs were characterized in detail and used for the development of amperometric sensors for AD determination. The amperometric sensors containing the best NLacs, as well as a natural fungal laccase, were constructed. The most effective nAuCePt-containing sensor had good specificity in relation to AD and improved analytical characteristics. It possessed a 384-fold higher sensitivity than adrenaline (230,137 A·M−1·m−2), a 64-fold lower limit of detection (0.025 µM), and a broader linear range (0.085–45 µM) in comparison with the sensor based on natural laccase. The constructed nAuCePt-containing sensor was successfully used for AD analysis in pharmaceutical formulation.

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Highly Sensitive and Selective Colorimetric Detection of Methylmercury Based on DNA Functionalized Gold Nanoparticles

Sensors ◽

10.3390/s18082679 ◽

2018 ◽

Vol 18 (8) ◽

pp. 2679 ◽

Cited By ~ 6

Author(s):

Zheng-Jun Xie ◽

Xian-Yu Bao ◽

Chi-Fang Peng

Keyword(s):

Gold Nanoparticles ◽

Catalytic Activity ◽

Limit Of Detection ◽

Low Cost ◽

Colorimetric Detection ◽

Colorimetric Method ◽

Optimal Conditions ◽

Surface Deposition ◽

Highly Sensitive ◽

Dna Strand

A new colorimetric detection of methylmercury (CH3Hg+) was developed, which was based on the surface deposition of Hg enhancing the catalytic activity of gold nanoparticles (AuNPs). The AuNPs were functionalized with a specific DNA strand (HT7) recognizing CH3Hg+, which was used to capture and separate CH3Hg+ by centrifugation. It was found that the CH3Hg+ reduction resulted in the deposition of Hg onto the surface of AuNPs. As a result, the catalytic activity of the AuNPs toward the chromogenic reaction of 3,3,5,5-tetramethylbenzidine (TMB)-H2O2 was remarkably enhanced. Under optimal conditions, a limit of detection of 5.0 nM was obtained for CH3Hg+ with a linear range of 10–200 nM. We demonstrated that the colorimetric method was fairly simple with a low cost and can be conveniently applied to CH3Hg+ detection in environmental samples.

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A rapid, accurate, scalable, and portable testing system for COVID-19 diagnosis

Nature Communications ◽

10.1038/s41467-021-23185-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Guanhua Xun ◽

Stephan Thomas Lane ◽

Vassily Andrew Petrov ◽

Brandon Elliott Pepa ◽

Huimin Zhao

Keyword(s):

Limit Of Detection ◽

Low Cost ◽

High Volume ◽

N Gene ◽

Testing System ◽

Target Sequence ◽

One Pot ◽

Sequence Detection ◽

Highly Sensitive ◽

Speed Accuracy

AbstractThe need for rapid, accurate, and scalable testing systems for COVID-19 diagnosis is clear and urgent. Here, we report a rapid Scalable and Portable Testing (SPOT) system consisting of a rapid, highly sensitive, and accurate assay and a battery-powered portable device for COVID-19 diagnosis. The SPOT assay comprises a one-pot reverse transcriptase-loop-mediated isothermal amplification (RT-LAMP) followed by PfAgo-based target sequence detection. It is capable of detecting the N gene and E gene in a multiplexed reaction with the limit of detection (LoD) of 0.44 copies/μL and 1.09 copies/μL, respectively, in SARS-CoV-2 virus-spiked saliva samples within 30 min. Moreover, the SPOT system is used to analyze 104 clinical saliva samples and identified 28/30 (93.3% sensitivity) SARS-CoV-2 positive samples (100% sensitivity if LoD is considered) and 73/74 (98.6% specificity) SARS-CoV-2 negative samples. This combination of speed, accuracy, sensitivity, and portability will enable high-volume, low-cost access to areas in need of urgent COVID-19 testing capabilities.

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Enhanced electrocatalytic activity of cobalt phthalocyanines when “clicked” to graphene oxide nanosheets

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424619500688 ◽

2019 ◽

Vol 23 (07n08) ◽

pp. 828-840 ◽

Cited By ~ 2

Author(s):

Lekhetho S. Mpeta ◽

Tebello Nyokong

Keyword(s):

Graphene Oxide ◽

Catalytic Activity ◽

Benzene Ring ◽

Electrocatalytic Activity ◽

Electrochemical Sensors ◽

Limit Of Detection ◽

Oxidation Potential ◽

Graphene Oxide Nanosheets ◽

Ring Complex ◽

Good Catalytic Activity

Alkyne-terminated Co phthalocyanine (CoPc) derivatives are linked to reduced graphene oxide nanosheets (GONS) via click chemistry and the conjugates are used for the electrocatalytic oxidation of 2-mercaptoethanol. CoPc derivatives where the alkyne group is separated from the Pc ring by an aliphatic and benzene ring (complex 3) showed the best catalytic activity (in terms of oxidation potential) in comparison to when only aliphatic chains were employed without the benzene ring (complex 2) and when there were no substituents (complex 1). The anodic oxidation of 2-mercaptoethanol on 3-GONS (linked) occurred at the least positive oxidation potential (-0.22 V vs. Ag|AgCl). 3-GONS (linked) was found to have the highest sensitivity with the lowest limit of detection of 0.08 [Formula: see text]M. When the CoPc derivative and GONS were not linked but placed sequentially on the electrode, the electrocatalytic activity (in terms of LOD) was poorer than when linked. The electrodes modified with CoPc clicked to GONS are highly promising electrochemical sensors in terms of stability, sensitivity, good catalytic activity and ease of fabrication.

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Optimization and Characterization of Paper-based SERS Substrates for Detection of Melamine

Communications in Physics ◽

10.15625/0868-3166/30/0/14832 ◽

2020 ◽

Vol 30 (4) ◽

pp. 345

Author(s):

Bich Ngoc Nguyen Thi ◽

Viet Ha Chu ◽

Thi Thuy Nguyen ◽

Trong Nghia Nguyen ◽

Hong Nhung Tran

Keyword(s):

Limit Of Detection ◽

Chemical Reduction ◽

Low Cost ◽

Sers Substrate ◽

Sers Substrates ◽

Surface Enhanced Raman ◽

Enhanced Raman Scattering ◽

Silver Nitrate Concentration ◽

Filter Papers

A flexible low-cost paper-based surface enhanced Raman scattering (SERS) substrate was successfully manufactured by a direct chemical reduction of silver nanoparticles (AgNPs) onto a common commercially available filter paper. Characterization of fabricated paper-based SERS substrate and the influences of the silver nitrate concentration, type of paper on SERS signal were systematically investigated. In order to fabricate SERS substrates with the highest quality, a suitable one from four different types of filter papers was chosen. The prepared SERS substrates have capability for detecting food toxic chemicals. The test of detecting melamine in aqueous solution was successfully demonstrated with the limit of detection for melamine is 10-7M.

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Sensing of Oxygen Partial Pressure in Air with ZnO Nanoparticles

Sensors ◽

10.3390/s20020562 ◽

2020 ◽

Vol 20 (2) ◽

pp. 562

Author(s):

Xin Chang ◽

Shunpu Li ◽

Daping Chu

Keyword(s):

Oxygen Partial Pressure ◽

Partial Pressure ◽

Low Cost ◽

Electrical Conductance ◽

Zno Nanoparticle ◽

Sensing Applications ◽

Highly Sensitive ◽

Sensitive Sensor ◽

Micrometer Scale ◽

Higher Sensitivity

The demand for sensors in response to oxygen partial pressure in air is increasingly high in recent years and small-size sensors on a micrometer scale and even a nanometer scale are particularly desirable. In this paper, the sensing of oxygen partial pressure in air was realized by a solution-processed ZnO nanoparticle (NP). Thin-film ZnO NP was prepared by spin-coating and a highly sensitive sensor was then fabricated. The oxygen sensing performance was characterized in air and compared with that in nitrogen, which showed an increase in electrical conductance by more than 100 times as a result of decreasing oxygen partial pressure from 103 mBar to 10−5 mBar. Moreover, higher sensitivity was achieved by increasing the annealing temperature and the effect of thermal annealing was also investigated. Furthermore, ZnO NP lines with 7 μm in width were successfully patterned with low cost by a mould-guided drying technique from ZnO NP dispersion, which makes ZnO NP extremely promising for miniaturized and integrated sensing applications.

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A Highly Sensitive Electrochemical Glucose Sensor Based on Room Temperature Exfoliated Graphite-Derived Film Decorated with Dendritic Copper

Materials ◽

10.3390/ma14175067 ◽

2021 ◽

Vol 14 (17) ◽

pp. 5067

Author(s):

Jiaxin Tang ◽

Luo Wei ◽

Shuaijie He ◽

Jihui Li ◽

Ding Nan ◽

...

Keyword(s):

Catalytic Activity ◽

High Performance ◽

High Stability ◽

Room Temperature ◽

Glucose Sensor ◽

Three Dimensional ◽

Exfoliated Graphite ◽

Highly Sensitive ◽

Free Glucose ◽

Good Catalytic Activity

An ultrasensitive enzyme-free glucose sensor was facilely prepared by electrodepositing three-dimensional dendritic Cu on a room temperature exfoliated graphite-derived film (RTEG-F). An excellent electrocatalytic performance was demonstrated for glucose by using Cu/RTEG-F as an electrode. In terms of the high conductivity of RTEG-F and the good catalytic activity of the dendritic Cu structures, the sensor demonstrates high sensitivities of 23.237 mA/mM/cm2, R2 = 0.990, and 10.098 mA/mM/cm2, R2 = 0.999, corresponding to the concentration of glucose ranging from 0.025 mM to 1.0 mM and 1.0 mM to 2.7 mM, respectively, and the detection limit is 0.68 μM. In addition, the Cu/RTEG-F electrode demonstrates excellent anti-interference to interfering species and a high stability. Our work provides a new idea for the preparation of high-performance electrochemical enzyme-free glucose sensor.

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Polyaniline as a Sacrificing Template for the Synthesis of Ultra-small Co3O4 Nanoparticles for the Sensitive and Selective Detection of Methotrexate (MTX)

10.21203/rs.3.rs-248125/v1 ◽

2021 ◽

Author(s):

Irum Naz Qureshi ◽

Aneela Tahira ◽

Khoulwod Aljadoa ◽

Ali M. Alsalme ◽

Asma A. Al-Othman ◽

...

Keyword(s):

Electrochemical Sensors ◽

Limit Of Detection ◽

Low Cost ◽

Metal Oxide Nanoparticles ◽

Linear Sweep Voltammetry ◽

Co3o4 Nanoparticles ◽

X Ray Diffraction ◽

Highly Sensitive ◽

Wide Range ◽

Average Size

Abstract The successful monitoring of the anticancer drugs using nanostructured materials is very important but very challenging task. Beside this, uniform and ultra-small size of metal oxide nanoparticles is highly needed in order to enhance the catalytic activity which could result into the development of sensitive and selective electrochemical sensors for methotrexate (MTX). For this purpose, we have used a simple approach involving the polyaniline (PANI) as a sacrificing template for the growth of uniform and ultra-small Co3O4 nanoparticles by hydrothermal method. The structure, shape, composition and phase purity were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform Infrared (FTIR) techniques. The average size of Co3O4 nanoparticles was below 50 nm. The cubic crystallography is confirmed for the Co3O4 nanoparticles. The electrochemical properties of PANI assisted Co3O4 nanoparticles for MTX drug was evaluated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) in Britton–Robinson buffer (BRB) of pH 3.5. The PANI assisted Co3O4 nanoparticles were found highly sensitive for the MTX drug and exhibited a linear range from 5-75µM of MTX and limit of detection for the modified electrode was estimated 1.98µM. The proposed electrochemical sensor is low cost, simple, highly sensitive and selective towards MTX detection. The synthetic methodology using the conducting polymer as a sacrificing template for the growth of controlled and ultra-small Co3O4 nanoparticles can be utilized for the wide range of electrochemical applications.

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A Nanocomposite Based on Reduced Graphene and Gold Nanoparticles for Highly Sensitive Electrochemical Detection of Pseudomonas aeruginosa through Its Virulence Factors

Materials ◽

10.3390/ma12071180 ◽

2019 ◽

Vol 12 (7) ◽

pp. 1180 ◽

Cited By ~ 6

Author(s):

Islem Gandouzi ◽

Mihaela Tertis ◽

Andreea Cernat ◽

Dalila Saidane-Mosbahi ◽

Aranka Ilea ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Gold Nanoparticles ◽

Bacterial Infections ◽

Electrochemical Sensors ◽

Tap Water ◽

Low Cost ◽

Biological Contamination ◽

Reduced Graphene ◽

Highly Sensitive ◽

Higher Sensitivity

Pyoverdine is a fluorescent siderophore produced by Pseudomonas aeruginosa that can be considered as a detectable marker in nosocomial infections. The presence of pyoverdine in water can be directly linked to the presence of the P. aeruginosa, thus being a nontoxic and low-cost marker for the detection of biological contamination. A novel platform was developed and applied for the electrochemical selective and sensitive detection of pyoverdine, based on a graphene/graphite-modified screen-printed electrode (SPE) that was electrochemically reduced and decorated with gold nanoparticles (NPs). The optimized sensor presenting higher sensitivity towards pyoverdine was successfully applied for its detection in real samples (serum, saliva, and tap water), in the presence of various interfering species. The excellent analytical performances underline the premises for an early diagnosis kit of bacterial infections based on electrochemical sensors.

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Highly Sensitive Electrochemical Aptasensor for Detecting the VEGF165 Tumor Marker with PANI/CNT Nanocomposites

Biosensors ◽

10.3390/bios11040114 ◽

2021 ◽

Vol 11 (4) ◽

pp. 114

Author(s):

Yunjeong Park ◽

Min-Sung Hong ◽

Woo-Hyuk Lee ◽

Jung-Gu Kim ◽

Kyunghoon Kim

Keyword(s):

Tumor Marker ◽

Limit Of Detection ◽

Biological Fluid ◽

Low Cost ◽

High Sensitivity ◽

Label Free ◽

Electrochemical Aptasensor ◽

Promising Tool ◽

Highly Sensitive ◽

Endothelial Growth Factor

Sensing targeted tumor markers with high sensitivity provides vital information for the fast diagnosis and treatment of cancer patients. A vascular endothelial growth factor (VEGF165) have recently emerged as a promising biomarker of tumor cells. The electrochemical aptasensor is a promising tool for detecting VEGF165 because of its advantages such as a low cost and quantitative analysis. To produce a sensitive and stable sensor electrode, nanocomposites based on polyaniline (PANI) and carbon nanotube (CNT) have potential, as they provide for easy fabrication, simple synthesis, have a large surface area, and are suitable in biological environments. Here, a label-free electrochemical aptasensor based on nanocomposites of CNT and PANI was prepared for detecting VEGF165 as a tumor marker. The nanocomposite was assembled with immobilized VEGF165 aptamer as a highly sensitive VEGF165 sensor. It exhibited stable and wide linear detection ranges from 0.5 pg/mL to 1 μg/mL, with a limit of detection of 0.4 pg/mL because of the complementary effect of PANI/CNT. The fabricated aptasensor also exhibited good stability in biological conditions, selectivity, and reproducibility after several measurement times after the dissociation process. Thus, it could be applied for the non-invasive determination of VEGF, in biological fluid diagnosis kits, or in an aptamer-based biosensor platform in the near future.

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An Innovative Polyaniline/Platinum-Coated Fiber Optic – Surface Plasmon Resonance Sensor for Picomolar Detection of 4-Nitrophenol

10.21203/rs.3.rs-183104/v1 ◽

2021 ◽

Author(s):

Iulia ANTOHE ◽

Iuliana IORDACHE ◽

Vlad-Andrei ANTOHE ◽

Gabriel SOCOL

Keyword(s):

Surface Plasmon Resonance ◽

Surface Plasmon ◽

Plasmon Resonance ◽

Fiber Optic ◽

Limit Of Detection ◽

Low Cost ◽

Cost Effective ◽

Coated Fiber ◽

Highly Sensitive ◽

Resonance Sensor

Abstract The paper reports for the first time an innovative polyaniline (PANI)/platinum (Pt)-coated fiber optic – surface plasmon resonance (FO-SPR) sensor used for highly-sensitive 4-nitrophenol (4-NP) pollutant detection. The Pt thin film was coated over an unclad core of an optical fiber (FO) using a DC magnetron sputtering technique, while the 4-NP responsive PANI layer was synthetized using a cost-effective electroless polymerization method. The presence of the electrolessly-grown PANI on the Pt-coated FO was observed by field-emission scanning electron microscopy (FE-SEM) and subsequently evidenced by energy dispersive X-ray analysis (EDX). These FO-SPR sensors with a demonstrated sensitivity of 1515 nm/RIU were then employed for 4-NP sensing, exhibiting am excellent limit of detection (LOD) in the low picomolar range (0.17 pM). The proposed sensor’s configuration has many other advantages, such as low-cost production, small size, immunity to electromagnetic interferences, remote sensing capability, and moreover, can be operated as a “stand-alone device”, making it thus well-suited for applications such as “on-site” screening of extremely low-level trace pollutants.

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