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Building an optical filtration function into a microfluidic chip is a promising way of simplifying the optical detection system of a microfluidic device. In this paper, a PDMS microfluidic chip filter that is capable of transmitting chlorophyll fluorescence and blocking interfering light in the visible wavelength range was developed for living algae detection with a smartphone. The chip was fabricated by sealing a layer of crystal violet solution in a PDMS layer on the top of the Sudan II-doped PDMS slab, which has a straight microchannel. Optimum dye concentrations and thicknesses for the crystal violet solution layer and Sudan II-doped PDMS slab were investigated and determined by spectrum measurements. It was found that the cut-on range of this integrated microfluidic chip is extended to about 625 nm and the transmittance in the chlorophyll fluorescence range (650 nm to 710 nm) is as high as 95%, when 25 mg L−1 Sudan II-doped PDMS slab (with a 3 mm thickness) and 2 mg L−1 crystal violet solution (with a 0.3 mm thickness) were used. Living algae detection using this chlorophyll-fluorescence-filtering PDMS microfluidic chip and a smartphone-based imaging platform was achieved, and the results compared favorably with those using a commercial filter. [ABSTRACT FROM AUTHOR]

Non-spherical flagellate algae play an increasingly significant role in handling problematic issues as versatile biological micro/nanorobots and resources of valuable bioproducts. However, the commensalism of flagellate algae with distinct structures and constituents causes considerable difficulties in their further biological utilization. Therefore, it is imperative to develop a novel method to realize high-efficiency selection of non-spherical flagellate algae in a non-invasive manner. Enthused by these, we proposed a novel method to accomplish the selection of flagellate algae based on the numerical and experimental investigation of dielectrophoretic characterizations of flagellate algae. Firstly, an arbitrary Lagrangian--Eulerian method was utilized to study the electro-orientation and dielectrophoretic assembly process of spindle-shaped and ellipsoid-shaped cells in a uniform electric field. Secondly, we studied the equilibrium state of spherical, ellipsoid-shaped, and spindle-shaped cells under positive DEP forces actuated by rightangle bipolar electrodes. Thirdly, we investigated the dielectrophoretic assembly and escape processes of the non-spherical flagellate algae in continuous flow to explore their influences on the selection. Fourthly, freshwater flagellate algae (Euglena, H. pluvialis, and C. reinhardtii) and marine ones (Euglena, Dunaliella salina, and Platymonas) were separated to validate the feasibility and adaptability of this method. Finally, this approach was engineered in the selection of Euglena cells with high viability and motility. This method presents immense prospects in the selection of pure non-spherical flagellate algae with high motility for chronic wound healing, bio-micromotor construction, and decontamination with advantages of no sheath, strong reliability, and shape-insensitivity. [ABSTRACT FROM AUTHOR]

A simple and potent chemosensor AFL has been successfully developed to recognize Sn2+ selectively in marine algae or, more precisely, seaweed, as they are at huge risk from marine contamination. The bioaccumulation of Sn2+, mainly by the algae community, poses a great threat to the entire environment as Sn2+ toxicity flows towards higher organisms through food chain. The chemosensor AFL shows high selectivity and sensitivity towards Sn2+ with an extremely low detection limit, i.e. 90 nM, and demonstrates turn-on fluorescence with a bright cyan blue colour. The interaction mechanism is well supported by absorption, fluorescence titration, NMR titration and mass spectrometry, as well as theoretical analysis. Moreover, tin accumulation in green algae has also been revealed efficiently through confocal microscopic imaging. The quantification studies demonstrate that the AFL probe can be used as a proficient fluorescent marker for detecting Sn2+ in aquatic plants to save the marine ecosystem. [ABSTRACT FROM AUTHOR]