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Guangzhou, China

Fatima A.,South China University of Technology | Wang H.,South China University of Technology | Kang K.,Guangzhou Wondfo Biotech Co. | Xia L.,Chinese National Human Genome Center at Shanghai | And 4 more authors.
PLoS ONE | Year: 2014

The possibility of using variable domain heavy-chain antibodies (VHH antibodies) as diagnostic tools for dengue virus (DENV) type 2 NS1 protein was investigated and compared with the use of conventional monoclonal antibodies. After successful expression of DENV type 2 NS1 protein, the genes of VHH antibodies against NS1 protein were biopanned from a non-immune llama library by phage display. VHH antibodies were then expressed and purified from Escherichia coli. Simultaneously, monoclonal antibodies were obtained by the conventional route. Sequence analysis of the VHH antibodies revealed novel and long complementarity determining regions 3 (CDR3). Epitope mapping was performed via a phage display peptide library using purified VHH and monoclonal antibodies as targets. Interestingly, the same region of NS1, which comprises amino acids 224HWPKPHTLW232, was conserved for both kinds of antibodies displaying the consensus motif histidine-tryptophan-tryptophan or tryptophan-proline-tryptophan. The two types of antibodies were used to prepare rapid diagnostic kits based on immunochromatographic assay. The VHH antibody immobilized rapid diagnostic kit showed better sensitivity and specificity than the monoclonal antibody immobilized rapid diagnostic kit, which might be due to the long CDR3 regions of the VHH antibodies and their ability to bind to the pocket and cleft of the targeted antigen. This demonstrates that VHH antibodies are likely to be an option for developing point-of-care tests against DENV infection. © 2014 Fatima et al. Source


Wu X.-L.,South China University of Technology | Yu S.-J.,South China University of Technology | Yu S.-J.,Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety | Kang K.-R.,Guangzhou Wondfo Biotech Co.
Food Chemistry | Year: 2014

In this study, an indirect competitive enzyme-linked immunoassay (ic-ELISA) based on monoclonal antibody for 4(5)-Methylimidazole (4-MI) detection was described. The artificial antigens were prepared by conjugating bovine serum albumin (BSA) or ovalbumin (OVA) with the hapten of 4-MI. And monoclonal antibody, evaluated by ic-ELISA, was obtained by immunizing BABL/c mice. After optimizing, a standard curve for ic-ELISA detection on 4-MI was obtained with the linear detection range of 0.64-20.48 mg/L. The cross-reactivity (CR) of all the structural analogues of 4-MI was less than 5.62%. The recoveries of 4-MI in caramels detection were ranged from 88.69% to 114.09%, with relative standard deviation (n = 3) below 8.07%. The results suggested that the established ic-ELISA is promising for 4-MI commercial detection in caramels. © 2014 Elsevier Ltd. All rights reserved. Source


Patent
Guangzhou Wondfo Biotech. Co. | Date: 2011-08-26

An analyzing and reading device and an analyzing and reading method, for reading and analyzing a test strip for assay detection are disclosed. The test strip has a detection zone and a blank zone, the device includes a photoelectric detection circuit and a processor, wherein the photoelectric detection circuit includes at least two light sources which locate corresponding to the positions of the detection zone and the blank zone of the test strip and are able to emit lights corresponding to the detection zone and blank zone of the test strip, and at least one optical detectors which receive reflected lights from the above two zones; wherein lights emitted by the at least two light sources irradiate the detection zone and blank zone of the strip and are reflected therefrom, and then are received by the optical detector, which in turn feedback the detection information to the processor; the processor making analysis and decision based on the detection information received. The analyzing and reading device and method according to the present invention have high accuracy and less interference when reading.


A method and system for intelligently identifying and reading an immunochromatographic strip is disclosed. The method includes the following steps: (a) preparing an immunochromatographic strip provided with a bar code, that is, setting a bar code on an immunochromatographic strip to form a bar code layer; (b) identifying the immunochromatographic strip provided with a bar code through a bar code identification circuit, and dispatching an analysis program corresponding to the type of the immunochromatographic strip provided with a bar code; (c) transmitting visible light to irradiate the immunochromatographic strip provided with a bar code through a light-emitting diode (LED) circuit controlled by a central processing unit; receiving reflected or transmitted light through a photoelectrical sensor and converting the received light into electrical signals; and then amplifying the electrical signals through a signal amplification circuit and transmitting the amplified signals to the central processing unit in order to analyze the signals through the analysis program dispatched in step (b); and (d) outputting an analysis result.


Patent
Guangzhou Wondfo Biotech. Co. | Date: 2015-01-20

A device and method for determining the assay result is disclosed. The device includes a photoelectric detection circuit and a processor, and an optical detection device which is set with a detection zone and a blank zone for measuring assay results, and the photoelectric detection circuit detects the light-reflection intensity signal, and feeds back the detected information to the processor, and the processor is preset with a threshold value changing with time, and determined value processed by the processor is compared with the preset threshold value to obtain the result of assay. The method for determining the assay result display the result when confirmed determined value is bigger than the preset threshold value or can not reach preset threshold value within a fixed time or detected signal can not be determined, wherein the threshold value changes with the time. The device and method for determining the assay result work more efficiently, measure more accurately and cost less than the prior art.

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