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1.
ACS Appl Mater Interfaces ; 13(35): 41445-41453, 2021 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-34428374

RESUMO

Airborne transmission of exhaled virus can rapidly spread, thereby increasing disease progression from local incidents to pandemics. Due to the COVID-19 pandemic, states and local governments have enforced the use of protective masks in public and work areas to minimize the disease spread. Here, we have leveraged the function of protective face coverings toward COVID-19 diagnosis. We developed a user-friendly, affordable, and wearable collector. This noninvasive platform is integrated into protective masks toward collecting airborne virus in the exhaled breath over the wearing period. A viral sample was sprayed into the collector to model airborne dispersion, and then the enriched pathogen was extracted from the collector for further analytical evaluation. To validate this design, qualitative colorimetric loop-mediated isothermal amplification, quantitative reverse transcription polymerase chain reaction, and antibody-based dot blot assays were performed to detect the presence of SARS-CoV-2. We envision that this platform will facilitate sampling of current SARS-CoV-2 and is potentially broadly applicable to other airborne diseases for future emerging pandemics.


Assuntos
Testes Respiratórios/instrumentação , Teste para COVID-19/instrumentação , Máscaras , SARS-CoV-2/isolamento & purificação , Microbiologia do Ar , Anticorpos Antivirais/imunologia , Testes Respiratórios/métodos , Teste para COVID-19/métodos , Colódio/química , Colorimetria/métodos , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Cimento de Policarboxilato/química , Porosidade , Estudo de Prova de Conceito , RNA Viral/análise , Reação em Cadeia da Polimerase em Tempo Real/métodos , SARS-CoV-2/química , Proteínas Virais/análise , Proteínas Virais/imunologia
2.
Sci Rep ; 11(1): 16430, 2021 08 12.
Artigo em Inglês | MEDLINE | ID: mdl-34385527

RESUMO

Until there is an effective implementation of COVID-19 vaccination program, a robust testing strategy, along with prevention measures, will continue to be the most viable way to control disease spread. Such a strategy should rely on disparate diagnostic tests to prevent a slowdown in testing due to lack of materials and reagents imposed by supply chain problems, which happened at the beginning of the pandemic. In this study, we have established a single-tube test based on RT-LAMP that enables the visual detection of less than 100 viral genome copies of SARS-CoV-2 within 30 min. We benchmarked the assay against the gold standard test for COVID-19 diagnosis, RT-PCR, using 177 nasopharyngeal RNA samples. For viral loads above 100 copies, the RT-LAMP assay had a sensitivity of 100% and a specificity of 96.1%. Additionally, we set up a RNA extraction-free RT-LAMP test capable of detecting SARS-CoV-2 directly from saliva samples, albeit with lower sensitivity. The saliva was self-collected and the collection tube remained closed until inactivation, thereby ensuring the protection of the testing personnel. As expected, RNA extraction from saliva samples increased the sensitivity of the test. To lower the costs associated with RNA extraction, we performed this step using an alternative protocol that uses plasmid DNA extraction columns. We also produced the enzymes needed for the assay and established an in-house-made RT-LAMP test independent of specific distribution channels. Finally, we developed a new colorimetric method that allowed the detection of LAMP products by the visualization of an evident color shift, regardless of the reaction pH.


Assuntos
Teste para COVID-19/métodos , COVID-19/virologia , Colorimetria/métodos , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , SARS-CoV-2/isolamento & purificação , COVID-19/diagnóstico , Humanos , Pandemias , Portugal/epidemiologia , RNA Viral/genética , SARS-CoV-2/genética , Saliva/química , Saliva/virologia , Sensibilidade e Especificidade
3.
Nucleic Acids Res ; 49(13): 7267-7279, 2021 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-34232998

RESUMO

We performed in vitro selection experiments to identify DNA aptamers for the S1 subunit of the SARS-CoV-2 spike protein (S1 protein). Using a pool of pre-structured random DNA sequences, we obtained over 100 candidate aptamers after 13 cycles of enrichment under progressively more stringent selection pressure. The top 10 sequences all exhibited strong binding to the S1 protein. Two aptamers, named MSA1 (Kd = 1.8 nM) and MSA5 (Kd = 2.7 nM), were assessed for binding to the heat-treated S1 protein, untreated S1 protein spiked into 50% human saliva and the trimeric spike protein of both the wildtype and the B.1.1.7 variant, demonstrating comparable affinities in all cases. MSA1 and MSA5 also recognized the pseudotyped lentivirus of SARS-CoV-2 with respective Kd values of 22.7 pM and 11.8 pM. Secondary structure prediction and sequence truncation experiments revealed that both MSA1 and MSA5 adopted a hairpin structure, which was the motif pre-designed into the original library. A colorimetric sandwich assay was developed using MSA1 as both the recognition element and detection element, which was capable of detecting the pseudotyped lentivirus in 50% saliva with a limit of detection of 400 fM, confirming the potential of these aptamers as diagnostic tools for COVID-19 detection.


Assuntos
Aptâmeros de Nucleotídeos , COVID-19/virologia , Biblioteca Gênica , Mutação , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/genética , Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/genética , Pareamento de Bases , Sequência de Bases , COVID-19/diagnóstico , Colorimetria/métodos , Humanos , Conformação de Ácido Nucleico , Técnica de Seleção de Aptâmeros
4.
Methods Mol Biol ; 2326: 327-337, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34097280

RESUMO

Trace metal elements, such as zinc, iron, copper, and manganese, play catalytic or structural roles in many enzymes and numerous proteins, and accordingly, contribute to a variety of fundamental biological processes. During the past decade, the fruit fly (Drosophila melanogaster) has become an important model organism for elucidating metal homeostasis in metazoan. We have been using Drosophila as a model to study metal metabolism for many years and have optimized simple and robust assays for determining the metal content in Drosophila, such as inductively coupled plasma mass spectrometry (ICP-MS), the activity assay of enzymes dependent on metals, and staining metal ions in tissues of Drosophila. In this chapter, we present the step-by-step detailed methods for detecting the metal content in Drosophila melanogaster during metal toxicity study.


Assuntos
Drosophila melanogaster/química , Metais/análise , Animais , Colorimetria/métodos , Drosophila melanogaster/enzimologia , Drosophila melanogaster/metabolismo , Ensaios Enzimáticos/métodos , Espectrometria de Massas/métodos , Metais/metabolismo , Metais/toxicidade , Oligoelementos/análise , Oligoelementos/metabolismo , Oligoelementos/toxicidade
5.
ACS Appl Mater Interfaces ; 13(25): 30205-30212, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-34137259

RESUMO

Bioskins possess a great ability to detect and deliver external mechanical or temperature stimuli into identifiable signals such as color changes. However, the integration of visualization with simultaneous detection of multiple complex external stimuli in a single biosensor device remains a challenge. Here we propose an all-solution-processed bioinspired stretchable electronic skin with interactive color changes and four-mode sensing properties. The fabricated biosensor demonstrates sensitive responses to various stimuli including pressure, strain, voltage, and temperature. Sensing visualization is realized by color changes of the e-skin from brown to green and finally bright yellow as a response to intensified external stimuli, suggesting great application potential in military defense, healthcare monitoring, and smart bionic skin.


Assuntos
Colorimetria/instrumentação , Dispositivos Eletrônicos Vestíveis , Colorimetria/métodos , Desenho de Equipamento , Humanos , Pressão , Temperatura
6.
Int J Biol Macromol ; 182: 2037-2047, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34087294

RESUMO

Novel sponge-like biochromic swab was developed via immobilization of natural anthocyanin (Cy) biomolecular probe into microporous cellulose aerogel. The current biosensor is characterized with simple preparation, environmentally-friendly, biocompatibility, biodegradability, flexibility, portability and reversibility. This biochromic sponge-like aerogel detector displayed a color change from pink to green-yellow in response to the biochemical changes occurs to sweat. This could be ascribed to intramolecular charge transfer occurs to the molecular system of Cy. Thus, the anthocyanin probe displayed colorimetric variations in UV-Vis absorption spectra via a blue shifting from 620 to 529 nm when raising the pH value of the prepared mimic sweat solution. Natural pH sensitive anthocyanin spectroscopic probe was extracted from red-cabbage plant, characterized by HPLC, and encapsulated into microporous cellulose. The microporous sponge-like cellulose swab was prepared by activating wood pulp utilizing phosphoric acid, and then subjected to freeze-drying. This anthocyanin probe is highly soluble in water. Thus, it was encapsulated as a direct dye into cellulose substrate during the freeze-drying process. To allow a better fixation of this water-soluble anthocyanin probe to the cellulose substrate, potash alum was added to the freeze-dried mixture to act as a fixing agent or mordant (M) generating Cy/M coordination complex. The produced Cy/M nanoparticles (NPs) were explored by transmission electron microscopy (TEM). The morphological features of the generated aerogels were investigated by scan electron microscope (SEM), energy-dispersive X-ray (EDX) spectra, and Fourier-transform infrared spectra (FT-IR). The cytotoxicity of the prepared aerogel-based biosensor was also evaluated. The naked-eye colorimetric changes were studied by exploring color strength, UV-Vis spectra and CIE Lab colorimetric coordinates.


Assuntos
Antocianinas/química , Brassica/química , Celulose/química , Colorimetria/métodos , Suor/química , Morte Celular , Cor , Cristalização , Células Epiteliais/citologia , Géis , Humanos , Concentração de Íons de Hidrogênio , Fenóis/análise , Espectrometria por Raios X , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Termogravimetria
7.
Theranostics ; 11(14): 6735-6745, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34093850

RESUMO

Background: Nucleic acid (NA)-based diagnostics enable a rapid response to various diseases, but current techniques often require multiple labor-intensive steps, which is a major obstacle to successful translation to a clinical setting. Methods: We report on a surface-engineered single-chamber device for NA extraction and in situ amplification without sample transfer. Our system has two reaction sites: a NA extraction chamber whose surface is patterned with micropillars and a reaction chamber filled with reagents for in situ polymerase-based NA amplification. These two sites are integrated in a single microfluidic device; we applied plastic injection molding for cost-effective, mass-production of the designed device. The micropillars were chemically activated via a nature-inspired silica coating to possess a specific affinity to NA. Results: As a proof-of-concept, a colorimetric pH indicator was coupled to the on-chip analysis of NA for the rapid and convenient detection of pathogens. The NA enrichment efficiency was dependent on the lysate incubation time, as diffusion controls the NA contact with the engineered surface. We could detect down to 1×103 CFU by the naked eye within one hour of the total assay time. Conclusion: We anticipate that the surface engineering technique for NA enrichment could be easily integrated as a part of various types of microfluidic chips for rapid and convenient nucleic acid-based diagnostics.


Assuntos
DNA Bacteriano/análise , Dispositivos Lab-On-A-Chip , Técnicas de Amplificação de Ácido Nucleico/instrumentação , Técnicas de Amplificação de Ácido Nucleico/métodos , Ácidos Nucleicos/isolamento & purificação , Colorimetria/métodos , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Humanos , Microfluídica/métodos , Microscopia Eletrônica de Varredura , Cimento de Policarboxilato/química , Reação em Cadeia da Polimerase em Tempo Real , Dióxido de Silício/química , Staphylococcus aureus/genética , Staphylococcus aureus/isolamento & purificação , Propriedades de Superfície
8.
J Mater Chem B ; 9(23): 4726-4734, 2021 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-34095946

RESUMO

The proportion of Fe2+ and Fe3+ in Fe-based nanozymes is a key point in determining their catalytic activity. However, it is hard to adjust the Fe2+/Fe3+ ratio in nanozyme systems to achieve the best catalytic performance. In this work, we successfully regulate Fe2+/Fe3+ ratios in a wide range of 0.81-1.45 based on a novel porous platform of Fe doped silica hollow spheres. The homogeneous distribution and stable fixation of Fe components in Fe doped silica hollow spheres facilitate the valence regulation of Fe in the reduction heating in H2/Ar. When the Fe doped spheres (FeOx@SHSs) were used as nanozymes, different Fe2+/Fe3+ ratios have shown to influence the peroxidase-like catalytic activity greatly. The highest activity at the ratio of 1.41 should be due to the combined effects of the accelerated reaction rate by Fe2+ and the enhanced catalytic cycle efficiency by Fe3+. The FeOx@SHSs-based nanozyme is further applied to construct a facile colorimetric biosensing system, which exhibited extremely sensitive determination of glucose. This work presents an effective platform for controlling Fe valences and optimizing the peroxidase-like activity for catalytic processes or sensing systems.


Assuntos
Colorimetria/métodos , Glucose/análise , Ferro/química , Nanopartículas Metálicas/química , Peroxidases/química , Limite de Detecção , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Temperatura
9.
Biosensors (Basel) ; 11(6)2021 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-34073756

RESUMO

Despite collaborative efforts from all countries, coronavirus disease 2019 (COVID-19) pandemic has been continuing to spread globally, forcing the world into social distancing period, making a special challenge for public healthcare system. Before vaccine widely available, the best approach to manage severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is to achieve highest diagnostic accuracy by improving biosensor efficacy. For SARS-CoV-2 diagnostics, intensive attempts have been made by many scientists to ameliorate the drawback of current biosensors of SARS-CoV-2 in clinical diagnosis to offer benefits related to platform proposal, systematic analytical methods, system combination, and miniaturization. This review assesses ongoing research efforts aimed at developing integrated diagnostic tools to detect RNA viruses and their biomarkers for clinical diagnostics of SARS-CoV-2 infection and further highlights promising technology for SARS-CoV-2 specific diagnosis. The comparisons of SARS-CoV-2 biomarkers as well as their applicable biosensors in the field of clinical diagnosis were summarized to give scientists an advantage to develop superior diagnostic platforms. Furthermore, this review describes the prospects for this rapidly growing field of diagnostic research, raising further interest in analytical technology and strategic plan for future pandemics.


Assuntos
Técnicas Biossensoriais/instrumentação , Teste para COVID-19/instrumentação , SARS-CoV-2/isolamento & purificação , Animais , Técnicas Biossensoriais/métodos , Teste para COVID-19/métodos , Colorimetria/instrumentação , Colorimetria/métodos , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Ensaio de Imunoadsorção Enzimática/instrumentação , Ensaio de Imunoadsorção Enzimática/métodos , Desenho de Equipamento , Humanos , Técnicas de Amplificação de Ácido Nucleico/instrumentação , Técnicas de Amplificação de Ácido Nucleico/métodos , Testes Imediatos
10.
Molecules ; 26(11)2021 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-34063849

RESUMO

Iron, one of the most common metals in the environment, plays a fundamental role in many biological as well as biogeochemical processes, which determine its availability in different oxidation states. Its relevance in environmental and industrial chemistry, human physiology, and many other fields has made it necessary to develop and optimize analysis techniques for accurate determination. Spectrophotometric methods are the most frequently applied in the analytical determination of iron in real samples. Taking advantage of the fact that desferrioxamine B, a trihydroxamic acid used since the 1970s in chelation therapy for iron overload treatment, forms a single stable 1:1 complex with iron in whichever oxidation state it can be found, a smart spectrophotometric method for the analytical determination of iron concentration was developed. In particular, the full compliance with the Lambert-Beer law, the range of iron concentration, the influence of pH, and the interference of other metal ions have been taken into account. The proposed method was validated in terms of LoD, LoQ, linearity, precision, and trueness, and has been applied for total iron determination in natural water certified material and in biological reference materials such as control human urine and control serum.


Assuntos
Desferroxamina/química , Quelantes de Ferro/química , Ferro/análise , Calibragem , Colorimetria/métodos , Humanos , Concentração de Íons de Hidrogênio , Ferro/urina , Ligantes , Limite de Detecção , Espectrometria de Massas/métodos , Reprodutibilidade dos Testes , Espectrofotometria Atômica/métodos , Espectrofotometria Ultravioleta/métodos , Água/química
11.
Food Chem ; 362: 130151, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34087707

RESUMO

Hydrogels based on alginate and methylcellulose were developed as a colorimetric indicator for monitoring minced pork spoilage. The hydrogel was fabricated by an external gelation method using Ca2+ as the crosslinking agent. The pH-sensitive dye bromothymol blue was incorporated into the hydrogel to act as an indicator. The hydrogel's swelling index increased with an increasing ratio of methylcellulose, suggesting that the water uptake capacity is tunable by the polymer composition. The hydrogel's compression strength is directly proportional to the alginate content. The hydrogel indicator demonstrated a color change from orange to yellow (day 6) upon detecting total volatile basic nitrogen (TVB-N) built up in the package during minced pork storage at 4 °C, and the results showed a positive correlation between the color change, TVB-N and pH change of minced pork. This result demonstrated the potential application of the hydrogel as a spoilage indicator in intelligent packaging.


Assuntos
Amônia/análise , Colorimetria/métodos , Análise de Alimentos/métodos , Hidrogéis/química , Carne de Porco/análise , Alginatos/química , Animais , Azul de Bromotimol/química , Cálcio/química , Cor , Colorimetria/instrumentação , Análise de Alimentos/instrumentação , Qualidade dos Alimentos , Armazenamento de Alimentos , Concentração de Íons de Hidrogênio , Metilcelulose/química , Nitrogênio/análise , Suínos , Água/química
12.
Malar J ; 20(1): 225, 2021 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-34011373

RESUMO

BACKGROUND: Loop-mediated isothermal amplification (LAMP) for malaria diagnosis at the point of care (POC) depends on the detection capacity of synthesized nucleic acids and the specificity of the amplification target. To improve malaria diagnosis, new colorimetric LAMP tests were developed using multicopy targets for Plasmodium vivax and Plasmodium falciparum detection. METHODS: The cytochrome oxidase I (COX1) mitochondrial gene and the non-coding sequence Pvr47 for P. vivax, and the sub-telomeric sequence of erythrocyte membrane protein 1 (EMP1) and the non-coding sequence Pfr364 for P. falciparum were targeted to design new LAMP primers. The limit of detection (LOD) of each colorimetric LAMP was established and assessed with DNA extracted by mini spin column kit and the Boil & Spin method from 28 microscopy infections, 101 malaria submicroscopic infections detected by real-time PCR only, and 183 negatives infections by both microscopy and PCR. RESULTS: The LODs for the colorimetric LAMPs were estimated between 2.4 to 3.7 parasites/µL of whole blood. For P. vivax detection, the colorimetric LAMP using the COX1 target showed a better performance than the Pvr47 target, whereas the Pfr364 target was the most specific for P. falciparum detection. All microscopic infections of P. vivax were detected by PvCOX1-LAMP using the mini spin column kit DNA extraction method and 81% (17/21) were detected using Boil & Spin sample preparation. Moreover, all microscopic infections of P. falciparum were detected by Pfr364-LAMP using both sample preparation methods. In total, PvCOX1-LAMP and Pfr364-LAMP detected 80.2% (81 samples) of the submicroscopic infections using the DNA extraction method by mini spin column kit, while 36.6% (37 samples) were detected using the Boil & Spin sample preparation method. CONCLUSION: The colorimetric LAMPs with multicopy targets using the COX1 target for P. vivax and the Pfr364 for P. falciparum have a high potential to improve POC malaria diagnosis detecting a greater number of submicroscopic Plasmodium infections.


Assuntos
Colorimetria/métodos , Malária Falciparum/diagnóstico , Malária Vivax/diagnóstico , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Plasmodium falciparum/isolamento & purificação , Plasmodium vivax/isolamento & purificação , Complexo IV da Cadeia de Transporte de Elétrons/análise , Plasmodium falciparum/enzimologia , Plasmodium vivax/enzimologia , Proteínas de Protozoários/análise
13.
Anal Bioanal Chem ; 413(17): 4451-4458, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34002276

RESUMO

Robust and sensitive cell-based enzyme-linked immunosorbent assay (CELISA) is of great significance in the diagnosis and screening of cancer. However, the method is limited by the high rate of negative results attributed to the instability of horseradish peroxidase (HRP), H2O2, and antibody. Here, we construct a folic acid-functionalized in situ-grown MnO2 nanosheet/graphene oxide hybrid (FA-MnO2/GO) with oxidase-like activity instead of the anti-folate receptor antibody in traditional CELISA to resist the possible negative interference arising from unstable HRP, H2O2, and antibodies for more robust colorimetric detection of cancer cells. The functionalization of FA enables the selective binding between hybrid and cancer cells through the over-expressed folate receptor, and then the binding events are converted into quantitative colorimetric signals though the oxidation of the chromogenic substrate TMB catalyzed by MnO2, allowing the detection of cancer cells with colorimetric method. Moreover, the construction of MnO2/GO hybrid can synergistically enhance the oxidase-like activity of MnO2 and promote its dispersion in water, further ensuring the accuracy and sensitivity of the detection. A detection limit of 20 cancer cells is obtained by a plate reader, which is lower than those obtained by most reported CELISA methods for cancer cell detection, and as few as 75 cancer cells can be identified by the naked eye. This study not only provides a multifunctional sensing platform for robust and sensitive cancer cell detection, but also offers a promising oxidase-like mimic in the field of bioanalysis.


Assuntos
Grafite/química , Compostos de Manganês/química , Nanoestruturas/química , Neoplasias/patologia , Óxidos/química , Materiais Biomiméticos/química , Técnicas Biossensoriais/métodos , Colorimetria/métodos , Ácido Fólico/química , Células HeLa , Humanos , Células MCF-7 , Neoplasias/diagnóstico , Oxirredutases/química
14.
Food Chem ; 359: 129962, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-33945984

RESUMO

Due to the biochemical and pharmacological activities, the convenient and effective detection of quercetin (Qc) is very important for biochemistry, pharmaceutical chemistry and clinical medicine. A kind of non-conjugated polymer dots (NCPDs) was used as a versatile and sensitive dual-mode optical output for Qc detection, which was synthesized by hyperbranched poly(ethylenimine) (PEI) and l-threonine via environmentallyfriendly way. The dual-mode method proposed in this work had high sensitivity and definiteselectivity for Qc detection. Additionally, it was convenient for the naked eyes to observe the fluorescence brightness and color change.


Assuntos
Colorimetria/métodos , Fluorometria/métodos , Polímeros/química , Quercetina/análise , Fluorescência , Humanos
15.
Anal Bioanal Chem ; 413(15): 4013-4022, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33961104

RESUMO

A facile and green approach to the preparation of peroxidase-like nanozymes by reducing and functionalizing graphene oxide (rGO) with Ganoderma polysaccharide (GP) has been achieved in this work. Our results showed that the as-fabricated nanozyme, namely rGO-GP, possessed the excellent property of simulating peroxidase with higher catalytic activity compared with GO or rGO obtained by using chitosan, which may be due to the better dispersion of rGO-GP in the solution. Steady-state kinetics studies further showed that the catalytic process conformed to Michaelis-Menten equation and ping-pong mechanism. Benefiting from the excellent peroxidase property of rGO-GP, we have also successfully established a highly sensitive and selective colorimetric detection approach to trace detection of L-cysteine (L-Cys). The limit of detection (LOD) of L-cysteine is 0.1 µM and the linear detection range is 2-30 µM. Furthermore, the nanozyme was successfully applied for detecting L-cysteine in serum. This work therefore demonstrates the advantages of rGO-GP as an effective nanozyme in both its green synthesis and detecting application.


Assuntos
Colorimetria/métodos , Cisteína/análise , Grafite/química , Química Verde , Peroxidase/química , Limite de Detecção
16.
J Mater Chem B ; 9(23): 4663-4669, 2021 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-34032252

RESUMO

Due to their specific spinel structure, ternary oxides with multi-catalytic sites on a highly active exposed surface are recommended as alternative bio-catalysts. Spinel zinc vanadate with two-dimensional nanosheets (Zn3V3O8 NSs) was synthesised using a one-step hydrothermal route with CTAB and glycine as a bi-surfactant, where each NS has a thin thickness (25 nm) and wide cross section (2 µm). As a key parameter for peroxidase-like activity, the Michaelis-Menten constant (Km) for Zn3V3O8 NSs was calculated to be 0.271 mM with TMB and 1.317 mM with H2O2 at optimum conditions, indicating a higher affinity for the exposed (011) facet towards horseradish peroxidases. This affinity is related to the geometric matching between V4+ active sites and the terminal amino groups of TMB. The V4+ ions on the (011) facet act as dangling bonds and readily react with H2O2 in a Fenton-like reaction. The peroxidase-like activity for Zn3V3O8 NSs is verified by the formation of [V(IV)-OO˙] by the ˙O2- and V5+ near V4+ sites, but oxidase activity for Zn3V3O8 NSs. Based on the peroxidase-like activity, Zn3V3O8 NSs were used as a colorimetric glucose sensor with a wide linear range from 0.01 to 0.5 mM and a detection limit (LOD = 3σ/S) of 2.81 × 10-7 M. The colorimetric sensor also exhibited high accuracy and selectivity in synthetic perspiration samples.


Assuntos
Colorimetria/métodos , Glucose/análise , Nanoestruturas/química , Peroxidases/química , Vanadatos/química , Compostos de Zinco/química , Limite de Detecção , Especificidade por Substrato
17.
ACS Appl Mater Interfaces ; 13(22): 26490-26497, 2021 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-34029053

RESUMO

Artificial skins with sensing ability have great potential in applications of wearable devices and soft robotics. Inspired by the functions of human skins including sensing stimuli via electrical signal and bruising for injury indication, an ionic conductive and mechanochromic organohydrogel is synthesized and demonstrated as ionic skin (I-skin). The gel consisting of mechanochromophore cross-linked micelles is mechanically robust, stretchable, and deformation durable with minor hysteresis, and it also displays good solvent retention. The change of relative resistance during elongation and compression suggests a high sensitivity. An optical change from pale yellow to bruise-like blue-purple color is observed under a large deformation. The ionic conductive organohydrogel as I-skin is attached to different parts of the human body with movements mimicking various body-bruising scenarios, demonstrating successful perception and visualization of mechanical stimuli. The work vividly presents a strain sensor with the functions of injury visualization and damage warning for mechanical impacts. The I-skin can be potentially used in the applications including prosthetic devices, wearable electronics, and intelligent robots.


Assuntos
Colorimetria/métodos , Condutividade Elétrica , Hidrogéis/química , Mecanotransdução Celular , Fenômenos Fisiológicos da Pele , Pele/fisiopatologia , Biomimética , Eletrônica , Humanos , Pele/lesões , Pele Artificial , Dispositivos Eletrônicos Vestíveis
18.
ACS Appl Mater Interfaces ; 13(21): 25044-25052, 2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-34019375

RESUMO

Integration of novel bio-/nanostructures as effective sensing platforms is still of great significance for robust and rapid analysis. Herein, a novel metal-organic framework-derived NiCo2O4 was synthesized via a feasible templating method. Significantly, redox couples of both Ni3+/Ni2+ and Co3+/Co2+ provided richer oxidation-reduction reactions, thereby leading to an enhanced catalytic activity. Furthermore, NiCo2O4 as an enzyme mimic with peroxidase-like activity and oxidase-like activity could oxidize colorless thylbenzidine (TMB) to blue oxTMB in the absence of H2O2. Thus, a sensitive chromogenic sensing platform for detecting Fe2+, thiourea, cysteine (Cys), and epigallocatechin-3-gallate (EGCG) was proposed. The colorimetric detection methods exhibited great features of low limit of detection (LOD) and broad linear range. Owing to the complexation reaction, the chromogenic sensing system of TMB + NiCo2O4 + Cys achieved effective detection of Cu2+ and Mn2+ with the LODs of 0.0022 and 0.0181 mM, respectively. Developed detection methods with wide linear ranges of 0.008-0.1 mM for Cu2+ and 0.08-1 mM for Mn2+ had excellent practical potential. Similarly, the reaction system of TMB + NiCo2O4 + EGCG could achieve the colorimetric detection of Cu2+ and Fe3+. The great chromogenic sensing performance for detecting Cu2+ and Fe3+ with a broad linear range and a low LOD could be also realized.


Assuntos
Colorimetria/métodos , Enzimas/química , Estruturas Metalorgânicas/química , Metais/análise , Mimetismo Molecular , Catálise , Limite de Detecção , Oxirredução , Proteínas/química
19.
Nat Protoc ; 16(6): 3141-3162, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33931780

RESUMO

The global pandemic of coronavirus disease 2019 (COVID-19) highlights the shortcomings of the current testing paradigm for viral disease diagnostics. Here, we report a stepwise protocol for an RNA-extraction-free nano-amplified colorimetric test for rapid and naked-eye molecular diagnosis of COVID-19. The test employs a unique dual-prong approach that integrates nucleic acid (NA) amplification and plasmonic sensing for point-of-care detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with a sample-to-assay response time of <1 h. The RNA-extraction-free nano-amplified colorimetric test utilizes plasmonic gold nanoparticles capped with antisense oligonucleotides (ASOs) as a colorimetric reporter to detect the amplified nucleic acid from the COVID-19 causative virus, SARS-CoV-2. The ASOs are specific for the SARS-CoV-2 N-gene, and binding of the ASOs to their target sequence results in the aggregation of the plasmonic gold nanoparticles. This highly specific agglomeration step leads to a change in the plasmonic response of the nanoparticles. Furthermore, when tested using clinical samples, the accuracy, sensitivity and specificity of the test were found to be >98.4%, >96.6% and 100%, respectively, with a detection limit of 10 copies/µL. The test can easily be adapted to diagnose other viral infections with a simple modification of the ASOs and primer sequences. It also provides a low-cost, rapid approach requiring minimal instrumentation that can be used as a screening tool for the diagnosis of COVID-19 at point-of-care settings in resource-poor situations. The colorimetric readout of the test can even be monitored using a handheld optical reader to obtain a quantitative response. Therefore, we anticipate that this protocol will be widely useful for the development of biosensors for the molecular diagnostics of COVID-19 and other infectious diseases.


Assuntos
Teste de Ácido Nucleico para COVID-19/métodos , COVID-19/diagnóstico , Ouro/química , Nanopartículas Metálicas/química , Oligonucleotídeos Antissenso/química , RNA Viral/análise , SARS-CoV-2/isolamento & purificação , COVID-19/virologia , Teste de Ácido Nucleico para COVID-19/instrumentação , Colorimetria/instrumentação , Colorimetria/métodos , Humanos , Limite de Detecção , Oligonucleotídeos Antissenso/genética , Testes Imediatos , RNA Viral/genética , SARS-CoV-2/genética
20.
Food Chem ; 358: 129900, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33933980

RESUMO

In this work, a syringe needle-based integrated method was designed for the detection of biogenic amines (BAs) in raw meat samples. Based on a sequential process, the needle-based sampling, micro liquid-phase extraction and peroxidase-like catalysis were adopted for the sample collection, target analytes extraction and colorimetric analysis, respectively. The proposed method exhibited high selectivity towards BAs (the total amount of histamine, putrescine and cadaverine was utilized to present the level of BAs), where the linear range is 5-50 µM and 50-1000 µM, and the limit of detection is 1.52 µM. Specifically, the whole process could be completed in a single syringe needle. In addition, due to the minimized sampling, the change of BAs levels with time in different area of real samples (fish) can be conveniently investigated. This method has the advantages of simplicity, low cost, high sensitivity and selectivity, endowing it a promising candidate for food analysis.


Assuntos
Aminas Biogênicas/análise , Colorimetria/métodos , Análise de Alimentos/instrumentação , Carne/análise , Amina Oxidase (contendo Cobre)/química , Animais , Cadaverina/análise , Catálise , Colorimetria/instrumentação , Produtos Pesqueiros/análise , Análise de Alimentos/métodos , Armazenamento de Alimentos , Histamina/análise , Microextração em Fase Líquida , Nanopartículas Metálicas/química , Agulhas , Peroxidase/química , Carne de Porco/análise , Putrescina/análise , Compostos de Estanho/química
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