This study aimed to develop non-metal elements for doping carbon quantum dots (CQDs) with nitrogen and sulfur (N, S-CQDs), which loaded inside hexagonal mesoporous silica (HMS) in order to effectively remove methylene blue dye (MB) from an aqueous solution. The histidine and cysteine amino acids were used as the source for synthesis N, S-CQDs through the hydrothermal method. Morphology and structure of the N, S-CQDs, and adsorbent (N, S-CQDs/HMS) were characterized by using different microscopic and spectroscopic techniques. The adsorption parameters such as adsorbent dosage (0.25–1 g/L), pH (2–10), contact time (15–75 min), and initial MB dye concentration (20–300 mg/L) were investigated. The maximum adsorption capacity and removal efficiency of MB were determined at 370.4 mg/g and 97%, respectively, under optimum conditions at 303 K. The adsorption isotherm studies were fitted with the Freundlich isotherm equation, and the dye removal kinetics of the adsorbent followed the pseudo-second-order model. Thermodynamic studies showed that the adsorption process had exothermic and spontaneous behavior. The removal of MB next to the Rhodamine B and Reactive Black 5 dyes indicated that the N, S-CQDs/HMS had excellent selective behavior for MB absorption. This prepared adsorbent could be well recycled with suitable activity after four repeated adsorption–desorption cycles. Results revealed that the porous characters, surface area, charge properties, reduction in the bandgap, and quantum yield of the N, S-CQDs/HMS were essential factors that affected dye adsorption.

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Since the traditional method generates biological waste, there is a significant demand for an easy, quick technique of blood type identification without contamination. In fact, individuals can be divided into four main blood groups whose antigens are available in red blood cell (RBC) membranes and the antibodies in the plasma. Here, UV-vis and photoluminescence (PL) spectroscopic methods are systematically used to find the spectra of blood typing antigens (A, B and AB) and antibodies i.e. A-Anti, B-Anti, AB-Anti and D reagent. The PL spectra of RBCs in different blood groups as well as the corresponding antibodies are successfully resolved for the purpose of blood typing. The unique photophysical characteristics of these biomolecules including signal intensity and peak emission wavelength in PL spectra are lucidly anticipated to accurately discriminate ABO groups. PL spectra of RBC in positive blood typing indicate larger signal and shorter emission peak wavelength corresponding to negative ones. Furthermore, the monoclonal antibody PL emissions emphasize that Anti-A benefits higher intensity and shorter peak wavelength (blue shift) than B-Anti. In the following, lucid blue shifts are obtained in terms of antibody concentrations accompanying the elevation of fluorescence signal, most likely due to the aggregation induced emission (AIE) phenomenon, quite the opposite of the aggregation-caused quenching (ACQ) that is widely observed from conventional chromophore. Those are envisaged as unique properties of each antibody to utilize in the spectral blood typing.