Optical absorbance-based rapid test for the detection of sickle cell trait and sickle cell disease at the point-of-care.

People afflicted with sickle cell disease (SCD) experience severe deterioration in quality of life. The disease is characterized by debilitating pain, anemia, and increased susceptibility to life threatening infections. This genetic disorder is endemic to many parts of the world. Extensive and accurate screening of individuals with sickle cell trait (SCT) in the population, coupled with genetic counselling can inhibit the propagation of the disease. The gold-standard techniques for the detection of sickle hemoglobin, such as capillary electrophoresis, HPLC, and genetic testing, are prohibitively expensive and time-consuming. Mass screening is usually conducted with a low-cost test called the solubility test, which does not offer high specificity. This study proposes a game-changing single-step low-cost method for rapidly yet accurately screening and diagnosing SCD and SCT. This method relies on the hitherto unexplored differences in the optical absorbance between diseased, trait, and normal blood samples, under deoxygenated conditions. The proposed method was tested in two phases of clinical validation: a pilot study and a blind study. A total of 438 patient samples were tested using the proposed method across the two phases. The proposed method offers an average accuracy, sensitivity, and specificity of 97.6%, 96.9%, and 98.6%, respectively. The proposed test has the potential to obliviate the conventional two-step process of screening and diagnostic tests as it can be used at the point-of-care with minimal training and yet yield results reliable enough to assess disability benefit claims.

Pebrine diagnosis using quantitative phase imaging and machine learning.

Pebrine is the most dreaded infectious disease of the silkworm and has devastated sericulture in Europe during the 18th century. Thereafter, if it is detected, the crop is burned to prevent further dissemination. The conventional microscopic examination of moth's body fluid is erroneous and it exacerbates on Metarhizium anisopliae (MA) contaminated test samples. This is due to the resemblance of pebrine and MA spores in the microscopic examination. Therefore, this study aims to demonstrate an efficient pebrine detection technique. In the proposed method, a motorised brightfield microscope is custom-made to acquire focused and defocused images of test spores. These images are used to produce quantitative phase images of the spores by the transport of intensity equation method. The phase images' histogram of oriented gradients feature is used by a machine learning classifier to categorise the spores. This system classified 92 pebrine and 185 MA spores with an accuracy of 97% at 0.04 seconds/spore. The duration taken for image acquisition is 2.5 minutes per sample (10 fields of view covering an area of 302 × 260 µm2 ). The proposed method shows reliable results in pebrine diagnosis and would be an efficient alternative for current approaches.

Handheld fluorometer for in-situ melamine detection via interference synthesis of dsDNA-templated copper nanoparticles.

Fluorescent copper nanoparticles templated by dsDNA have gained significant research interest as they are inexpensive and easy to synthesize, and have found applications in the detection of a wide range of analytes. The presence of the analyte in the reaction mixture interferes with the synthesis of the copper nanoparticles and the subsequent drop in fluorescence can be correlated to the concentration of the analyte present in the solution. Analyte detection using copper nanoparticle-based assays is amenable for in-situ applications as the test does not require expensive reagents and can be performed at room temperature. However, expensive and sophisticated detection systems are required for the detection of copper nanoparticles due to the low fluorescence emission signal from these nanoparticles. This restricts the use of the technology to centralized labs. Utilizing a recently developed chemical technique for fluorescence enhancement, this paper presents the first report of a handheld fluorometer capable of detecting DNA-templated copper nanoparticles. The fluorometer is portable and constructed with low-cost, off-the-shelf components like a UV-LED and a PIN photodiode. The performance of the developed system is demonstrated through the detection of melamine in milk samples via the interference synthesis of copper nanoparticles. Melamine is an adulterant used in dairy products that is harmful to human health if present in levels above 1 ppm. The developed system is capable of detecting up to 0.1 ppm of melamine in milk samples with a linear relationship observed between the detector output and concentration of melamine in the range from 0.1 ppm to 100 ppm (R2 = 0.9979).