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Issue 48, 2011
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New ratiometric optical oxygen and pH dual sensors with three emission colors for measuring photosynthetic activity in cyanobacteria

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Abstract

Photosynthetic algae and cyanobacteria have been proposed for producing biofuels through a direct photoconversion process. To accelerate the efforts of discovering and screening microbes for biofuel production, sensitive and high throughput methods to measure photosynthetic activity need to be developed. Here we report the development of new ratiometric optical oxygen and pH dual sensors with three emission colors for measuring photosynthetic activities directly. The dual sensor system can measure oxygen (O2) generation and pH increase resulted from carbon dioxide (CO2) consumption simultaneously. The sensor was prepared by a copolymerization of three monomeric probes, an intra-reference probe (IRP) which does not respond to pH or O2, a probe for pH sensing (pHS), and an O2probe for O2 sensing (OS) with 2-hydroxyethyl methacrylate (HEMA) and acrylamide (AM). After polymerization, the three probes were chemically immobilized in an ion and O2 permeable poly(2-hydroxyethyl methacrylate)-co-polyacrylamide (PHEMA-co-PAM) matrix. The resulted sensing films (membranes) exhibited three emission colors with well separated emission spectra, covering blue, green, and red emission windows, under 380 nm light excitation. Responses of the sensors to pH and dissolved O2 were investigated in buffers and cyanobacterial cell cultures (Synechocystis sp. PCC 6803). In spite of the strong autofluorescence from cyanobacteria, the sensors were able to determine the pH values and dissolved O2 concentrations accurately and reproducibly. The measured results using the optical sensors were well in accordance with measurements using electrochemical electrodes with minimal experimental variations. The sensors were further applied for evaluation of photosynthetic activities of Synechocystis sp. PCC 6803 at the exponential and stationary phases. The results were consistent with biological observation that the photosynthetic activity in the exponential phase was higher than that in the stationary phase.

Graphical abstract: New ratiometric optical oxygen and pH dual sensors with three emission colors for measuring photosynthetic activity in cyanobacteria

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Publication details

The article was received on 04 Aug 2011, accepted on 18 Oct 2011 and first published on 03 Nov 2011


Article type: Paper
DOI: 10.1039/C1JM13754A
Citation: J. Mater. Chem., 2011,21, 19293-19301
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    New ratiometric optical oxygen and pH dual sensors with three emission colors for measuring photosynthetic activity in cyanobacteria

    H. Lu, Y. Jin, Y. Tian, W. Zhang, M. R. Holl and D. R. Meldrum, J. Mater. Chem., 2011, 21, 19293
    DOI: 10.1039/C1JM13754A

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