•One step top down synthesis of Aggregated Induced Emissive nanoparticles.•Novel TPEDH bio-functionalised nanoparticles.•Low cost paper based immunoassay with AIEgen signal generation.Low cost paper based immunoassays are receiving interest due to their fast performance and small amounts of biomolecules needed for developing an immunoassay complex. In this work aggregation-induced emissive (AIE) nanoparticles, obtained from a diastereoisomeric mixture of 1,2-di-(4-hydroxyphenyl)-1,2-diphenylethene (TPEDH) in a one-step top-down method, are characterized through Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), and Zeta potential. By measuring the Zeta potential before and after labeling the nanoparticles with antibodies we demonstrate that the colloidal system is stable in a wide pH-range. The AIE-active nanoparticles are deposited on chitosan and glutaraldehyde modified paper pads overcoming the common aggregation-caused quenching (ACQ) effect. Analyte concentrations from 1000 ng and below are applied in a model immunocomplex using Goat anti-Rabbit IgG and Rabbit IgG. In the range of 7.81 ng–250 ng, linear trends with a high R2 are observed, which leads to a strong increase of the blue fluorescence from the TPEDH nanoparticles.

Thick film oxygen electrodes manufactured by screen print method have been used as a transducer for a biochemical oxygen demand (BOD) sensor. The kinetics of the immobilized yeast, Arxula adeninivorans (Arxula) has been studied. The apparent KM of immobilized Arxula (>100 μM) is higher than free cells of Arxula (70 μM). The increase in KM caused by the effect of immobilization extends the linear range of the sensor. End-point measurement and quasi-kinetic measurement have been studied comparatively as measurement procedures with a good correlation. The Vmax for end-point measurement is 790.7 μM/s and that for quasi-kinetic measurement is 537.3 μM/s. The limit of detection is calculated 1.24 mg/l BOD. Using the quasi-kinetic measurement, instead of end-point measurements, the measuring time can be reduced from 5–30 min to 100 s. The sensor layer thickness or increase in the layer of covering gel can increase the KM that is accompanied with the extension of the linear range of the sensor. Nevertheless, increase in the layer of covering gel will not increase the saturation signal. Domestic wastewater was checked by the thick film BOD sensor and the results are satisfactory.

In the present study, we describe an InfectCheck barcode-style lateral flow assay for semi-quantitative detection of CRP in distinguishing between bacterial and viral infections. The severity of bacterial infection can be assessed by simply counting the number of red lines developed at the CRP test zone of the test device. If only one visible line appeared at the CRP test zone, it represents a low or mild inflammation with CRP levels < 10 mg/L. Two and three visible lines mean moderate (≥ 10–25 mg/L) and severe (≥ 25–50 mg/L) inflammations respectively while four visible lines stand for a very severe inflammation (≥ 50–100 mg/L). If the visible lines become faint and the intensity of the first line is weaker than that of the control line and may even disappear, this outcome corresponds to the stage of having super severe inflammation (≥ 100 mg/L). A total of 500 patients admitted to hospital through the Accident and Emergency Unit at the Prince of Wales Hospital were examined. The InfectCheck CRP barcode-style rapid test gave a high sensitivity of 88.7% and a high negative predictive value of 93.8%. This result indicates that the rapid test is reliable to exclude non-infected patients. The calculated intra- and inter-assay coefficient of variation for the five CRP concentration ranges was both within 20.0%. It is a one-step whole blood rapid test without any sample pre-treatment and the result is available within 20 min. This user friendly diagnostic tool can allow self-testing by interested individuals without any expensive reading device.