Study of Clinical Sample Detection for LH With Lateral Flow Immunochromatographic Strip Using Support Vector Regression

Membrane-based lateral flow immuno-chromatographic strip (LFICS) is widely used in the measurement of Luteinizing hormone (LH) because of its advantages such as easy to handle, low costs, room temperature storage and transport, no need for long storage or transportation of samples and no requirement for skilled technicians. However, LFICS can only provide qualitative or semi-quantitative results without quantitative information, which greatly limited its application. In this paper, we developed a novel quantitative detection method for LFICS using support vector regression (SVR). Canny edge detection operator and fuzzy c-means (FCM) clustering algorithm were also used to extract test line, control line and background part from LFICS images taken by smartphone. The features extracted from test line, control line and background part were used as the input features of SVR model to obtain LH concentration. Measurements of standard sample and clinical sample using proposed method were conducted. Concentration results of standard LH solutions obtained from this method showed a fine linear relationship (r = 0.985) from 1.0 to 250.0 mIU/mL. Seventy-eight clinical serum samples were detected and its corresponding correlation coefficient was 0.918. The method was used to track the urine LH level of a volunteer during ovulation, and quantitative results could be obtained within 15 min.

A rapid quantitative determination method of Luteinizing hormone with gold immunochromatographic strip

Measurement of Luteinizing hormone (LH) levels is of great importance in guidance for pregnancy, diagnosis of ovarian diseases and evaluation of clinical effect. Gold immunochromatographic strip(GICS) assay is a rapid, simple, low-costs, and on-site technology. Quantitative detection of GICS has advantage over the traditional qualitative or semi-quantitative strip assay. In this paper, we developed a novel quantitative detection method for GICS based on smart-phone. First, smart-phone was used to acquire GICS image. Then, we applied the canny edge detection operator to extract the reading window from GICS image, and the fuzzy c-means (FCM) clustering algorithm to locate the test and control lines in the reading window. In order to reduce environmental interference, luminance compensation based on color constancy algorithms was applied. Finally, the property of the developed quantitative method is demonstrated by the detection of LH sample and clinical serum sample. Experimental results revealed that this method could achieve a low detection limit of 1.0 mIU/mL in a linear range from 1.0 to 125.0 mIU/mL. Furthermore, the proposed method could be used for the determination of clinical serum samples and its corresponding correlation coefficients were 0.964. Results showed that this novel method could be an effective tool for the rapid quantitative determination of LH.

Evaluation of a rapid quantitative determination method of PSA concentration with gold immunochromatographic strips

BACKGROUND

Prostate cancer remains the most common cancer in men. Qualitative or semi-quantitative immunochromatographic measurements of prostate specific antigen (PSA) have been shown to be simple, noninvasive and feasible. The aim of this study was to evaluate an optimized gold immunochromatographic strip device for the detection of PSA, in which the results can be analysed using a Chromogenic Rapid Test Reader to quantitatively assess the test results.

METHODS

This reader measures the reflectance of the signal line via a charge-coupled device camera. For quantitative analysis, PSA concentration was computed via a calibration equation. Capillary blood samples from 305 men were evaluated, and two independent observers interpreted the test results after 12 min. Blood samples were also collected and tested with a conventional quantitative assay.

RESULTS

Sensitivity, specificity, positive and negative predictive values, and accuracy of the PSA rapid quantitative test system were 100, 96.6, 89.5, 100, and 97.4 %, respectively. Reproducibility of the test was 99.2, and interobserver variation was 8 % with a false positive rate of 3.4 %. The correlation coefficient between the ordinary quantitative assay and the rapid quantitative test was 0.960.

CONCLUSIONS

The PSA rapid quantitative test system provided results quickly and was easy to use, so that tests using this system can be easily performed at outpatient clinics or elsewhere. This system may also be useful for initial cancer screening and for point-of-care testing, because results can be obtained within 12 min and at a cost lower than that of conventional quantitative assays.

Antigen detection based on background fluorescence quenching immunochromatographic assay

Gold immunochromatographic assay (GICA) has been around for quite a while, but it is qualitative in the vast majority of applications. A fast, simple and quantitative GICA is in call for better medicine. In the current study, we have established a novel, quantitative GICA based on fluorescence quenching and nitrocellulose membrane background signals, called background fluorescence quenching immunochromatographic assay (bFQICA). Using model analyte alpha-fetoprotein (AFP), the present study assessed the performance of bFQICA in numerous assay aspects. With serial dilutions of the international AFP standard, standard curves for the calculation of AFP concentration were successfully established. At 10 and 100ngmL(-1) of the international AFP standard, the assay variability was defined with a coefficient of variance at 10.4% and 15.2%, respectively. For samples with extended range of AFP levels, bFQICA was able to detect AFP at as low as 1ngmL(-1). Fluorescence in bFQICA strips stayed constant over months. A good correlation between the results from bFQICA and from a well-established Roche electrochemiluminescence immunoassay was observed in 27 serum samples (r=0.98, p<0.001). In conclusion, our study has demonstrated distinctive features of bFQICA over conventional GICA, including utilization of a unique fluorescence ratio between nitrocellulose membrane background and specific signals (F1/F2) to ensure accurate measurements, combined qualitative and quantitative capabilities, and exceptionally high sensitivity for detection of very low levels of antigens. All of these features could make bFQICA attractive as a model for antigen-antibody complex based GICA, and could promote bFQICA to a broad range of applications for investigation of a variety of diseases.