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Background Vivax malaria diagnosis remains a challenge in malaria elimination, with current point of care rapid diagnostic tests (RDT) missing many clinically significant infections because of usually lower peripheral parasitaemia. Haemozoin-detecting assays have been suggested as an alternative to immunoassay platforms but to date have not reached successful field deployment. Haemozoin is a paramagnetic crystal by-product of haemoglobin digestion by malaria parasites and is present in the food vacuole of malaria parasite-infected erythrocytes. This study aimed to compare the diagnostic capability of a new haemozoin-detecting platform, the Gazelle™ device with optical microscopy, RDT and PCR in a vivax malaria-endemic region. Methods A comparative, double-blind study evaluating symptomatic malaria patients seeking medical care was conducted at an infectious diseases reference hospital in the western Brazilian Amazon. Optical microscopy, PCR, RDT, and Gazelle™ were used to analyse blood samples. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and Kappa values were calculated. Results Out of 300 patients, 24 test results were excluded from the final analysis due to protocol violation (6) and inconclusive and/or irretrievable results (18). Gazelle™ sensitivity was 96.1 % (91.3–98.3) and 72.1 % (65.0–78.3) when compared to optical microscopy and PCR, respectively whereas it was 83.9 % and 62.8 % for RDTs. The platform presented specificity of 100 % (97.4–100), and 99.0 % (94.8–99.9) when compared to optical microscopy, and PCR, respectively, which  was the same for RDTs. Its correct classification rate was 98.2 % when compared to optical microscopy and 82.3 % for PCR; the test’s accuracy when compared to optical microscopy was 98.1 % (96.4–99.7), when compared to RDT was 95.2 % (93.0–97.5), and when compared to PCR was 85.6 % (82.1–89.1). Kappa (95 % CI) values for Gazelle™ were 96.4 (93.2–99.5), 88.2 (82.6–93.8) and 65.3 (57.0–73.6) for optical microscopy, RDT and PCR, respectively. Conclusions The Gazelle™ device was shown to have faster, easier, good sensitivity, specificity, and accuracy when compared to microscopy and was superior to RDT, demonstrating to be an alternative for vivax malaria screening particularly in areas where malaria is concomitant with other febrile infections (including dengue fever, zika, chikungunya, Chagas, yellow fever, babesiosis).

Diamond Nitrogen vacancy (NV) color center-based weak magnetic field detection is a popular topic for quantum sensing. The primary method of NV color center magnetic field measurement is the optical detection magnetic resonance (ODMR) method, including three main steps laser polarization, microwave excitation, and fluorescence signal collection. Then the intensities of the fluorescence signals are outputted as an ODMR curve where the magnetic field parameters can be directly observed. However, microwave excitation requires using a large number of frequencies by scanning the frequencies in a specific range, resulting in high complexity and low efficiency. Less than 50% of the microwave excitations are useful, and the rest works barely help to measure. The reason is that only the resonance peaks contain the magnetic field information, so only the microwave frequencies around the resonance peaks need to be excited. Therefore, we consider exciting only a few frequency microwaves. This paper proposes a random frequency microwave excitation method based on the Lorentz function fitting reconstruction, referred to as the under-sampling reconstruction based ODMR (USR-ODMR). It only excites several microwave frequencies randomly to produce the ODMR curve. The main idea of USR-ODMR is to select proper frequencies from random frequencies by employing the constant false alarm rate-based threshold. At last, a diamond NV color center magnetometer is implemented and tested to obtain ODMR curves. Experimental results show that the USR-ODMR can accurately reconstruct the ODMR curves with much lower complexity than the traditional ODMR method.

To develop a simple assay for the capture and detection of rare cancer cells in whole blood using iron oxide-gold (IO-Au) nanoparticles. IO-Au nanoovals (NOVs) were synthesized, coated with Raman tags and linked with antibodies targeting breast cancer. An integrated system was constructed for on-line magnetic cell capture and surface-enhanced Raman scattering (SERS) detection. The capabilities of IO-Au SERS NOVs to capture and detect rare cancer cells in blood were investigated in the integrated system using circulating tumor cell-mimic SK-BR-3 cells. SK-BR-3 cells in whole blood were magnetically captured under a flow condition using IO-Au SERS NOVs, followed by on-line SERS detection with a limit of detection of 1-2 cells/ml blood. We developed a sensitive method that can capture and detect cancer cells in whole blood with a single nanoconstruct, which is highly promising for the detection of circulating tumor cells in the clinic. Original submitted 7 December 2012; Revised submitted 25 March 2013