posted on 2021-03-11, 16:39authored byNathaniel
E. Kallmyer, Mohamed Seddik Abdennadher, Sparsh Agarwal, Rebecca Baldwin-Kordick, Rachel L. Khor, Alex S. Kooistra, Erica Peterson, Marshall D. McDaniel, Nigel F. Reuel
The
practical impact of analytical probes that transduce in the
near-infrared (nIR) has been dampened by the lack of cost-effective
and portable nIR fluorimeters. Herein, we demonstrate straightforward
designs for an inexpensive microplate reader and a portable fluorimeter.
These instruments require minimally complex machining and fabrication
and operate with an open-source programming language (Python). Complete
wiring diagrams, assembly diagrams, and scripts are provided. To demonstrate
the utility of these two instruments, we performed high-throughput
and field-side measurements of soil samples to evaluate the effect
of soil management strategies on extracellular proteolytic, cellulolytic,
and lignin-modifying activities. This was accomplished with fluorescent
enzyme probes that utilized uniquely sensitive transducers exclusive
to the nIR spectrum, single-walled carbon nanotubes. We also used
the portable fluorimeter to evaluate spatial variations of proteolytic
activity within individual field plots, while minimizing the effects
of soil storage and handling. These demonstrations indicate the utility
of these fluorimeters for translating analytical probes that operate
in the nIR beyond the laboratory and into actual use.