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Vitamin D deficiency is associated with various diseases such as obesity, digestive problems, osteoporosis, depression, and infections, and has therefore emerged as a topic of great interest in public healthcare. The quantitative assessment of 25-hydroxyvitamin D (25-OH VD) in human serum may accurately reflect the nutritional status of vitamin D in the human body, which is significant for the prevention and treatment of vitamin D-deficient patients. In this study, we developed an assay for quantitative detection of 25-OH VD based on the 25-OH VD monoclonal antibody (mAb), and identified the optimal process parameters. The following process settings were found to be suitable for the test strips: pH of 7.6, 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) ratio of 1:2000, and the anti-25-OH VD mAb ratio was 1:8. The equilibration time of the immune dynamic assay was 15 min. Under optimal conditions, the quantum dot nanoparticle-based fluorescent immunochromatographic assay (QDs-FICA) exhibited dynamic linear detection of 25-OH VD in PBS, from 5 ng/mL to 100 ng/mL, and the strip quantitative curve could be represented by the following regression equation: y = −0.02088 logx)+1.444 (R2 = 0.9050). The IC50 of the QDs-FICA was 39.6 ± 1.33 ng/mL. The specificity of the QDs-FICA was evaluated by running several structurally related analogues, including 25-OH VD2, 25-OH VD3, 1,25-OH2VD3, 1,25-OH2VD2, VD2, and VD3. The coefficients of variation were all below 10%. The shelf life of the test strips in this study was about 160 days at room temperature. Briefly, this study is the first to perform QDs-FICA for the rapid visual and quantitative detection of 25-OH VD, with great potential significance for clinical diagnosis of vitamin D-associated diseases.

Drug abuse is becoming increasingly dangerous nowadays. Morphine (MOP), methamphetamine (MET) and ketamine (KET) are the most commonly abused drugs. The abuse of these drugs without supervision can cause serious harm to the human body and also endanger public safety. Developing a rapid and accurate method to screen drug suspects and thus control these drugs is essential to public safety. This paper presents a method for the simultaneous quantitative detection of these three drugs in hair by a europium nanoparticles-based fluorescence immunochromatographic assay (EuNPs−FIA). In our study, the test area of the nitrocellulose membrane was composed of three equally spaced detection lines and a quality control line. The test strip realized the quantitative analysis of the samples by detecting the fluorescence brightness of the europium nanoparticles captured on the test line within 15 min. For the triple test strip, the limits of detection of MOP, KET and MET were 0.219, 0.079 and 0.329 ng/mL, respectively. At the same time, it also showed strong specificity. The strip was stable and could be stored at room temperature for up to one year, and the average recovery rate was 85.98–115.92%. In addition, the EuNPs−FIA was validated by high-performance liquid chromatography (HPLC) analysis, and a satisfactory consistency was obtained. Compared to the current immunochromatographic methods used for detecting abused drugs in hair, this method not only increased the number of detection targets, but also ensured sensitivity, improving detection efficiency to a certain extent. The approach can also be used as an alternative to chromatography. It provides a rapid and accurate screening method for the detection of abused drugs in hair and has great application prospects in regard to public safety. [ABSTRACT FROM AUTHOR]

Gizzerosine is a biogenic amine produced in fish meal drying process and posted higher mortality due to gizzard erosion in poultry than histamine. However, it is difficult to obtain gizzerosine and achieve sensitive practical detection due to its simple structure. Herein, a monoclonal antibody (mAb) specific to gizzerosine was generated based on the new structural design and a fluorescence immunosensor for sensitive and on-site detection of gizzerosine in feed was first established. Molecular modeling of the three-dimensional (3D) structure and surface electrostatic potential of gizzerosine indicated that the carbonyl group of gizzerosine hapten might affect the important sites of antigen-antibody interactions. The proposed structure was used to obtain the sensitive and specific mAb with IC 50 of 3.88 ng/mL in indirect competitive ELISA which was approximately 100-fold lower than that of direct competitive ELISA. Considering the practical application scenarios, a fluorescence immunosensor based on microporous dry method integrated with independent quality control line was established to improve detection stability. Under the optimum conditions, the proposed immunosensor showed a good linear relationship from 1.10 to 19.78 ng/mL and provided a low detection limit of 50 ng/g which was approximately 80-fold lower than the maximum recommended amount (0.4 mg/kg) of gizzerosine in feed. The recoveries of 6 kinds of feed ranged from 83.1 % to 114.3 %, which was in good consistence with that of UHPLC–MS/MS. Overall, this work provides a fast, cost-effective and reliable on-site tool for rapid screening of gizzerosine residues in feed samples. [Display omitted] • A novel hapten different from the original gizzerosine was designed for the first time. • A highly sensitive and specific anti-gizzerosine monoclonal antibody based on the novel hapten was prepared. • Relationship between antibody and hapten was studied by molecular modeling. • A fluorescence immunosensor was firstly developed for the on-site detection of gizzerosine. • The microporous dry method integrated with independent quality control line can be used for on-site detection. [ABSTRACT FROM AUTHOR]

Drug abuse is becoming increasingly dangerous nowadays. Morphine (MOP), methamphetamine (MET) and ketamine (KET) are the most commonly abused drugs. The abuse of these drugs without supervision can cause serious harm to the human body and also endanger public safety. Developing a rapid and accurate method to screen drug suspects and thus control these drugs is essential to public safety. This paper presents a method for the simultaneous quantitative detection of these three drugs in hair by a europium nanoparticles-based fluorescence immunochromatographic assay (EuNPs−FIA). In our study, the test area of the nitrocellulose membrane was composed of three equally spaced detection lines and a quality control line. The test strip realized the quantitative analysis of the samples by detecting the fluorescence brightness of the europium nanoparticles captured on the test line within 15 min. For the triple test strip, the limits of detection of MOP, KET and MET were 0.219, 0.079 and 0.329 ng/mL, respectively. At the same time, it also showed strong specificity. The strip was stable and could be stored at room temperature for up to one year, and the average recovery rate was 85.98–115.92%. In addition, the EuNPs−FIA was validated by high-performance liquid chromatography (HPLC) analysis, and a satisfactory consistency was obtained. Compared to the current immunochromatographic methods used for detecting abused drugs in hair, this method not only increased the number of detection targets, but also ensured sensitivity, improving detection efficiency to a certain extent. The approach can also be used as an alternative to chromatography. It provides a rapid and accurate screening method for the detection of abused drugs in hair and has great application prospects in regard to public safety.

Abstract Background Schistosomiasis japonica is a severe zoonosis. Domestic animals are the primary source of infection and play an important role in disease transmission. Surveillance and diagnosis play key roles in schistosomiasis control; however, current techniques for the surveillance and diagnosis of the disease have limitations. In this study, we developed a novel fluorescence immunochromatographic assay (FICA) strip to detect anti-Schistosoma japonicum antibodies in host serum. Methods A FICA strip was developed for the diagnosis of Schistosoma japonicum in domestic animals. Streptococcus protein G (SPG) and soluble egg antigen (SEA) were transferred onto a nitrocellulose (NC) membrane to form the control line (C) and the test line (T), respectively. With fluorescence activity as well as binding activity to multispecies IgG, the recombinant protein rSPG-RFP was expressed and employed as an antibody indicator in the FICA strips. Results The dual gene fusion plasmid was verified by PCR and restriction enzyme digestion. The expressed recombinant protein was 39.72 kDa in size, which was consistent with the predicted molecular weight. The western blot results showed binding activity between rSPG-RFP and IgGs from different hosts. Fluorescence microscopy also showed the fluorescence activity of the protein present. The affinity constant (Ka) values of rSPG-RFP with rabbit, donkey, mouse and goat IgG were 1.9 × 105, 4.1 × 105, 1.7 × 105 and 5.4 × 105, respectively. Moreover, based on the recombinant protein, the test strip for detecting S. japonicum in buffaloes could distinguish positive from negative serum. The lower limit of detection of the FICA strip was 1:10,000. Compared with ELISA, the FICA strips exhibited similar results in the diagnosis of infection in clinical bovine serum samples, with a kappa value of 0.9660 and P

Fluorescence immunochromatographic assay (FICA) is a quantitative detection technique widely used in clinical diagnosis, environmental monitoring, and food safety. To deal with the limited applications caused by insufficient detection range, this paper proposes a photoelectric adjustment system suitable for FICA strip readers to expand its detection range. The photoelectric adjustment system is proposed based on the relationship between the excitation light intensity and the fluorescence intensity, which provides the optimal excitation light intensity and a stable baseline amplitude for the FICA strip reader. To verify the proposed system, it was applied to the strip reader we had previously developed. The results show that the linear detection range of the FICA strip reader was extended from 1.95-256 μg/mL to 1-1024 μg/mL after using the proposed method. At the same time, the accuracy of the FICA strip reader does not deteriorate and is in good comparisons with the conventional ESEQuant Lateral Flow Reader (with R2 > 0.9987). Therefore, the proposed photoelectric adjustment method and system can improve the detection range of the strip reader or other similar devices.

Background: Schistosomiasis japonica is a severe zoonosis. Domestic animals are the primary source of infection and play an important role in disease transmission. Surveillance and diagnosis play key roles in schistosomiasis control; however, current techniques for the surveillance and diagnosis of the disease have limitations. In this study, we developed a novel fluorescence immunochromatographic assay (FICA) strip to detect anti-Schistosoma japonicum antibodies in host serum. Methods: A FICA strip was developed for the diagnosis of Schistosoma japonicum in domestic animals. Streptococcus protein G (SPG) and soluble egg antigen (SEA) were transferred onto a nitrocellulose (NC) membrane to form the control line (C) and the test line (T), respectively. With fluorescence activity as well as binding activity to multispecies IgG, the recombinant protein rSPG-RFP was expressed and employed as an antibody indicator in the FICA strips. Results: The dual gene fusion plasmid was verified by PCR and restriction enzyme digestion. The expressed recombinant protein was 39.72 kDa in size, which was consistent with the predicted molecular weight. The western blot results showed binding activity between rSPG-RFP and IgGs from different hosts. Fluorescence microscopy also showed the fluorescence activity of the protein present. The affinity constant (Ka) values of rSPG-RFP with rabbit, donkey, mouse and goat IgG were 1.9 × 105, 4.1 × 105, 1.7 × 105 and 5.4 × 105, respectively. Moreover, based on the recombinant protein, the test strip for detecting S. japonicum in buffaloes could distinguish positive from negative serum. The lower limit of detection of the FICA strip was 1:10,000. Compared with ELISA, the FICA strips exhibited similar results in the diagnosis of infection in clinical bovine serum samples, with a kappa value of 0.9660 and P < 0.01. The cross-reactivities of the FICA strips with Haemonchus contortus and Schistosoma turkestanicum (30.15% and 91.66%, respectively) were higher than those of ELISA (26.98% and 87.5%, respectively). Conclusions: Based on the rSPG-RFP protein that we developed, strip detection can be completed within 15 min. Heightened sensitivity allows the strip to accurately identify schistosome antibodies in serum. In conclusion, this method is convenient, feasible, rapid and effective for detecting S. japonicum. [ABSTRACT FROM AUTHOR]

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Fluorescence immunochromatographic assay (FICA) is a quantitative detection technique widely used in clinical diagnosis, environmental monitoring, and food safety. To deal with the limited applications caused by insufficient detection range, this paper proposes a photoelectric adjustment system suitable for FICA strip readers to expand its detection range. The photoelectric adjustment system is proposed based on the relationship between the excitation light intensity and the fluorescence intensity, which provides the optimal excitation light intensity and a stable baseline amplitude for the FICA strip reader. To verify the proposed system, it was applied to the strip reader we had previously developed. The results show that the linear detection range of the FICA strip reader was extended from 1.95-256 μg/mL to 1-1024 μg/mL after using the proposed method. At the same time, the accuracy of the FICA strip reader does not deteriorate and is in good comparisons with the conventional ESEQuant Lateral Flow Reader (with R2 > 0.9987). Therefore, the proposed photoelectric adjustment method and system can improve the detection range of the strip reader or other similar devices. [ABSTRACT FROM AUTHOR]

One-step fluorescence immunochromatographic assay (FICA) has been developed using fluorescent microspheres-labelled monoclonal antibody (McAb) probe for the rapid detection of copper ions in herbal plants and soil samples were investigated in this study. The results can be read by the fluorescence reader according to the fitted standard curve equation. Under optimal conditions, detecting copper ions with FICA can be done within 15 min with a LOD (limit of detection) of 0.2 μg/L, and was very useful for the rapid onsite testing. A total of 31 solid samples were pre-treated by microwave digestion combined with cation exchange solid phase extraction and prepared as test samples for FICA and ICP-AES. The two methods showed good relativity with correlation coefficients of 0.924 and 0.969 in herbal plants and soil samples for copper detection, respectively. We hope that our research can help promote the daily monitoring of heavy metal pollution effectively.

One-step fluorescence immunochromatographic assay (FICA) has been developed using fluorescent microspheres-labelled monoclonal antibody (McAb) probe for the rapid detection of copper ions in herbal plants and soil samples were investigated in this study. The results can be read by the fluorescence reader according to the fitted standard curve equation. Under optimal conditions, detecting copper ions with FICA can be done within 15 min with a LOD (limit of detection) of 0.2 μg/L, and was very useful for the rapid onsite testing. A total of 31 solid samples were pre-treated by microwave digestion combined with cation exchange solid phase extraction and prepared as test samples for FICA and ICP-AES. The two methods showed good relativity with correlation coefficients of 0.924 and 0.969 in herbal plants and soil samples for copper detection, respectively. We hope that our research can help promote the daily monitoring of heavy metal pollution effectively. [ABSTRACT FROM AUTHOR]

Vitamin D deficiency is associated with various diseases such as obesity, digestive problems, osteoporosis, depression, and infections, and has therefore emerged as a topic of great interest in public healthcare. The quantitative assessment of 25-hydroxyvitamin D (25-OH VD) in human serum may accurately reflect the nutritional status of vitamin D in the human body, which is significant for the prevention and treatment of vitamin D-deficient patients. In this study, we developed an assay for quantitative detection of 25-OH VD based on the 25-OH VD monoclonal antibody (mAb), and identified the optimal process parameters. The following process settings were found to be suitable for the test strips: pH of 7.6, 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) ratio of 1:2000, and the anti-25-OH VD mAb ratio was 1:8. The equilibration time of the immune dynamic assay was 15 min. Under optimal conditions, the quantum dot nanoparticle-based fluorescent immunochromatographic assay (QDs-FICA) exhibited dynamic linear detection of 25-OH VD in PBS, from 5 ng/mL to 100 ng/mL, and the strip quantitative curve could be represented by the following regression equation: y = -0.02088 logx)+1.444 (R2 = 0.9050). The IC50 of the QDs-FICA was 39.6 ± 1.33 ng/mL. The specificity of the QDs-FICA was evaluated by running several structurally related analogues, including 25-OH VD 2 , 25-OH VD 3 , 1,25-OH 2 VD 3 , 1,25-OH 2 VD 2 , VD 2 , and VD 3 . The coefficients of variation were all below 10%. The shelf life of the test strips in this study was about 160 days at room temperature. Briefly, this study is the first to perform QDs-FICA for the rapid visual and quantitative detection of 25-OH VD, with great potential significance for clinical diagnosis of vitamin D-associated diseases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Wang, Sun, Li, Zhu, Sun, Lv and Yue.)

Fluorescence immunochromatographic assay (FICA) is a rapid immunoassay technique that has the characteristics of high precision and sensitivity. Although image FICA strip readers have the advantages of high portability and easy operation, the use of high-precision complementary metal oxide semiconductor (CMOS) image sensors leads to an increase in overall cost. Considering the popularity of CMOS image sensors in smartphones and their powerful processing functions, this work developed a smartphone-based FICA strip reader. An optical module suitable for the test strips with different fluorescent markers was designed by replacing the excitation light source and the light filter. An android smartphone was used for image acquisition and image denoising. Then, the test and control lines of the test strip image were recognized by the sliding window algorithm. Finally, the characteristic value of the strip image was calculated. A linear detection range from 10 to 5000 mIU/mL (R2 = 0.95) was obtained for human chorionic gonadotrophin with the maximum relative error less than 9.41%, and a linear detection range from 5 to 4000 pg/mL (R2 = 0.99) was obtained for aflatoxin B1, with the maximum relative error less than 12.71%. Therefore, the smartphone-based FICA strip reader had high portability, versatility, and accuracy.

As an emerging technology, fluorescence immunochromatographic assay (FICA) has the advantages of high sensitivity, strong stability and specificity, which is widely used in the fields of medical testing, food safety and environmental monitoring. The FICA reader based on image processing meets the needs of point-of-care testing because of its simple operation, portability and fast detection speed. However, the image gray level of common image sensors limits the detection range of the FICA reader, and high-precision image sensors are expensive, which is not conducive to the popularization of the instrument. In this paper, FICA strips’ image was collected using a common complementary metal oxide semiconductor (CMOS) image sensor and a range adjustment mechanism was established to automatically adjust the exposure time of the CMOS image sensor to achieve the effect of range expansion. The detection sensitivity showed a onefold increase, and the upper detection limit showed a twofold increase after the proposed method was implemented. In addition, in the experiments of linearity and accuracy, the fitting degree (R2) of the fitted curves both reached 0.999. Therefore, the automatic range adjustment method can obviously improve the detection range of the FICA reader based on image processing.

The isoenzyme creatine kinase MB is very important for diagnosis of acute myocardial infarction (AMI). Some CK-MB immunoassays are sensitive, accurate and available for clinical application, but they are expensive and time-consuming procedures. Furthermore, conventional fluorescence immunochromatographic assays (FL-ICAs) have suffered from background fluorescence interference and low analytical sensitivity. A rapid and simple FL-ICA with Eu (III) chelate polystyrene microparticles was developed to determine CK-MB in 50uL serum samples using a portable test strip reader by measuring the fluorescence peak heights of the test line (H) and the control line (H) in 12 min. The assay was reliable with a good correlation coefficient between H/H ratio and CK-MB concentration in samples. A linear range was 0.85-100.29 ng/mL for CK-MB, and the LOD was 0.029 ng/mL. The intra- and inter-assay coefficients of variation (CV) were both <10 % and the average recoveries were from 90.17 % -112.63 % for CK-MB. The system performed well in interference experiments. Furthermore, a highly significant correlation ( r = 0.9794, P < 0.001) between this method and the commercially available bioMérieux mini VIDAS system were attained for measuring 120 CK-MB samples. These results indicated that the Eu (III) chelate microparticles-based FL-ICA is simple, fast, highly sensitive, reliable, and reproducible for point-of-care testing of CK-MB concentrations in serum. [ABSTRACT FROM AUTHOR]

Abstract: Southeast Asian deletion (−−SEA) α-thalassemia is an inherited monogenic disorder of human hemoglobin, and embryonic globin ζ (hemoglobin ζ, zeta globin chain or Hb zeta chain) has been shown to be a marker that can be used for the identification of carriers of the (−−SEA) α-thalassemia deletion. In this work, a fluorescence immunochromatographic assay (FL-ICA) was established to detect the zeta globin chain in the hemolysates of carriers of the (−−SEA) α-thalassemia deletion. This assay can be completed within 10min using a simple UV detector and does not suffer from interference from the red background color of the hemolysate. A total of 314 blood samples were tested by FL-ICA and ELISA. The results of these assays were confirmed by PCR, the standard technique for genetic disease testing. The sensitivity and specificity of this novel FL-ICA were 100% and 98.0%, respectively; the corresponding values for the ELISA performed simultaneously were 100% and 99.2%, respectively. In conclusion, a new FL-ICA–a simple, fast, convenient, low-cost method–was developed that may be useful in both high-throughput screening and individual detection of the (−−SEA) α-thalassemia deletion in carriers. Additionally, this qualitative FL-ICA may enlighten the development of a new systems for analysis of other target molecules using whole-blood samples. [Copyright &y& Elsevier]

A fluorescence immunochromatographic strip was developed in this study for natamycin detection in food. The results showed that the best amount of labeled antibody was 10 μg, for every 50 μj of fluorescent microspheres with a 2.5% (w/v) concentration. This labeled antibody was diluted for 10 times, and the diluted solution was dispensed into conjugate pad at the amount of 3μl/cm. The concent rat ions of natamycin labeled BSA for test line and goat anti-mouse for control line were 2.0 and 1 mg/ ml, respectively, which performed best. With the best conditions, the limit of detection was 1 ng/ml, the linearity ranged from 2 to 100 ng/ml, the recovery was about 80% to 120% , and the CV was below 23%. [ABSTRACT FROM AUTHOR]

Background: C-reactive protein (CRP) is emerging as a potential risk predictor for future cardiovascular diseases (CVD). High sensitivity assays have been developed and applied for clinical purposes. Methods: The fluorescence immunochromatographic assay was employed to detect and quantify CRP in whole blood. It consisted of a fluorescence (FL) antibody detector buffer, a test strip housed in a disposable cartridge, and a laser fluorescence scanner. Whole blood sample was mixed with detector, loaded onto a cartridge, incubated for 10 min, and the concentration of CRP was measured in a laser fluorescence scanner. The linearity, limit of detection (LOD), and performance of new assay system was tested and evaluated. The comparability of assay was examined with an automated reference method. Results: With the new assay system, a reliable correlation of coefficient (r) was obtained between the ratio value (AT/AC) and a concentration of CRP in samples. The linearity fell in the range of 0–10 mg/l of CRP, and the analytical detection limit was 0.133 mg/l of CRP. The mean recovery of the control was 105.2% in a working range. The precision of the intra- and inter-assay in a range of 0.5–6 mg/l was CVs <6% and <8%, respectively. The new fluorescence immunochromatographic assay system correlated well with a traditional immunoturbidimetric assay for quantification of CRP concentration (r=0.955, N=90). Conclusion: The fluorescence immunochromatographic assay is fast, reliable, and a reproducible platform for point-of-care testing (POCT) of high-sensitive (hs)-CRP in whole blood. [Copyright &y& Elsevier]

Rapid, reliable and easy-to-implement diagnostics that can be adapted in early severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnosis are critical to combat the epidemic. SARS-CoV-2 nucleocapsid protein (NP) is an ideal target for viral antigen-based detection. A rapid and convenient method was developed based on fluorescence immunochromatographic (FIC) assay to detect the SARS-CoV-2 NP antigen. However, the accuracy of this diagnostic method needs to be examined. This prospective study was carried out between 10 and 15 February 2020 in seven hospitals in Wuhan and one hospital in Chongqing, China. Participants with clinically suspected SARS-CoV-2 infection were enrolled. NP antigen testing by FIC assay and nucleic acid (NA) testing by real-time reverse transcriptase PCR (RT-PCR) were performed simultaneously in a blinded manner with the same nasopharyngeal swab sample. The diagnostic accuracy of NP antigen testing was calculated by taking NA testing of RT-PCR as the reference standard, in which samples with a cycle threshold (C t) value of ≤40 were interpreted as positive for SARS-CoV-2. A total of 253 participants were enrolled; two participants were excluded from the analyses because of invalid NP testing results. Of 251 participants (99.2%) included in the diagnostic accuracy analysis, 201 (80.1%) had a C t value of ≤40. With C t value 40 as the cutoff of NA testing, the sensitivity, specificity and percentage agreement of the FIC assay was 75.6% (95% confidence interval, 69.0–81.3), 100% (95% confidence interval, 91.1–100) and 80.5% (95% confidence interval, 75.1–84.9) respectively. With RT-PCR assay as the reference standard, NP antigen testing by FIC assay shows high specificity and relatively high sensitivity in SARS-CoV-2 diagnosis in the early phase of infection. [ABSTRACT FROM AUTHOR]

Fluorescence immunochromatographic assay (FICA) is a rapid immunoassay technique that has the characteristics of high precision and sensitivity. Although image FICA strip readers have the advantages of high portability and easy operation, the use of high-precision complementary metal oxide semiconductor (CMOS) image sensors leads to an increase in overall cost. Considering the popularity of CMOS image sensors in smartphones and their powerful processing functions, this work developed a smartphone-based FICA strip reader. An optical module suitable for the test strips with different fluorescent markers was designed by replacing the excitation light source and the light filter. An android smartphone was used for image acquisition and image denoising. Then, the test and control lines of the test strip image were recognized by the sliding window algorithm. Finally, the characteristic value of the strip image was calculated. A linear detection range from 10 to 5000 mIU/mL (R2 = 0.95) was obtained for human chorionic gonadotrophin with the maximum relative error less than 9.41%, and a linear detection range from 5 to 4000 pg/mL (R2 = 0.99) was obtained for aflatoxin B1, with the maximum relative error less than 12.71%. Therefore, the smartphone-based FICA strip reader had high portability, versatility, and accuracy. [ABSTRACT FROM AUTHOR]

As an emerging technology, fluorescence immunochromatographic assay (FICA) has the advantages of high sensitivity, strong stability and specificity, which is widely used in the fields of medical testing, food safety and environmental monitoring. The FICA reader based on image processing meets the needs of point-of-care testing because of its simple operation, portability and fast detection speed. However, the image gray level of common image sensors limits the detection range of the FICA reader, and high-precision image sensors are expensive, which is not conducive to the popularization of the instrument. In this paper, FICA strips' image was collected using a common complementary metal oxide semiconductor (CMOS) image sensor and a range adjustment mechanism was established to automatically adjust the exposure time of the CMOS image sensor to achieve the effect of range expansion. The detection sensitivity showed a onefold increase, and the upper detection limit showed a twofold increase after the proposed method was implemented. In addition, in the experiments of linearity and accuracy, the fitting degree (R2) of the fitted curves both reached 0.999. Therefore, the automatic range adjustment method can obviously improve the detection range of the FICA reader based on image processing. [ABSTRACT FROM AUTHOR]

As an emerging technology, fluorescence immunochromatographic assay (FICA) has the advantages of high sensitivity, strong stability and specificity, which is widely used in the fields of medical testing, food safety and environmental monitoring. The FICA reader based on image processing meets the needs of point-of-care testing because of its simple operation, portability and fast detection speed. However, the image gray level of common image sensors limits the detection range of the FICA reader, and high-precision image sensors are expensive, which is not conducive to the popularization of the instrument. In this paper, FICA strips' image was collected using a common complementary metal oxide semiconductor (CMOS) image sensor and a range adjustment mechanism was established to automatically adjust the exposure time of the CMOS image sensor to achieve the effect of range expansion. The detection sensitivity showed a onefold increase, and the upper detection limit showed a twofold increase after the proposed method was implemented. In addition, in the experiments of linearity and accuracy, the fitting degree ( R 2 ) of the fitted curves both reached 0.999. Therefore, the automatic range adjustment method can obviously improve the detection range of the FICA reader based on image processing.

Background: Myoglobin, creatine kinase-MB isoenzyme (CK-MB), and cardiac troponin I (cTnI) are cardiac biomarkers that are widely used to assist in the early and late diagnoses of acute myocardial infarction (AMI). Here, we present a clinically applicable fluorescence (FL) immunoassay for cardiac biomarkers., Methods: Whole blood was mixed with FL-labeled detector Ab (antibody) and then loaded onto a capture Ab-immobilized strip in a test cartridge. The FL intensities at test and control line on the strip were obtained and converted in a laser FL scanner to determine the concentration of biomarker. The analytical performance of immunoassay system was evaluated by linearity and imprecision tests. The comparability of the FL immunoassay method was examined with a reference method., Results: FL intensities and the levels of myoglobin, CK-MB, and cTnI displayed good linearity and high correlations (r = 0.999, 0.998, and 0.989, respectively). The coefficient of variations (CVs) of imprecision for all cardiac biomarkers were less than 8% in both intra- and interassays. When the results from the developed method and bioMerieux VIDAS assay were analyzed by Bland-Altman plot and Passing-Bablok plot, the two assay methods were in good agreement., Conclusion: The FL immunoassay system can provide a platform for point-of-care testing (POCT), and it is an easy, fast, and reliable method for the quantification of cardiac biomarkers., (© 2014 Wiley Periodicals, Inc.)