Date of download: 7/1/2016 Copyright © 2016 SPIE. All rights reserved. Three approaches to biosensing: (a) a single-analyte biosensor; (b) an array of biosensors operating in parallel for multianalyte analysis with multichannel signals processed by a computer; (c) a biomolecular logic system performing multianalyte analysis with the input signals chemically processed and the final generated output in a binary YES/NO form. Figure Legend: From: Role of biomolecular logic systems in biosensors and bioactuators Opt. Eng. 2014;53(9): doi: /1.OE

Date of download: 7/1/2016 Copyright © 2016 SPIE. All rights reserved. The simultaneous presence of biomarkers with limited specificity indicates a definitive YES conclusion, represented by the overlapping region in the diagram. Using the biochemical computing approach, this conclusion is realized as the output YES (or 1) of a multi-input AND logic gate, obtained only when all three inputs are present in their concentration ranges corresponding to 1. The output NO (or 0) is obtained for all other combinations of inputs. The “truth table” for a three-input AND gate and its logic diagram are also shown. Figure Legend: From: Role of biomolecular logic systems in biosensors and bioactuators Opt. Eng. 2014;53(9): doi: /1.OE

Date of download: 7/1/2016 Copyright © 2016 SPIE. All rights reserved. (a) Biocatalytic cascade for the analysis of liver injury (LI), activated by enzymes (inputs), alanine transaminase (ALT), and lactate dehydrogenase (LDH) for an AND logic gate. (b) The optical absorbance changes analogous to the decreasing concentration of NADH upon application of different combinations of the input signals. The inset shows the normalized output signals measured at 600 s from the start of the reaction. (c) and (d) The biocatalytic cascade and absorbance changes for a similar system operating with an added biochemical “filter” partially resetting the output signal back to nearly its zero level, as long as the filter-activating substrate is not fully consumed. The inset in (d) shows the normalized output signals measured at 600 s with improved separation between the logic outputs 0 and 1. The following abbreviations for products and intermediates are used: Pyr for pyruvate, Lac for lactate, Glu for glutamate, Ala for L-alanine, and α-KTG for α-ketoglutaric acid. The filter enzyme is glucose 6 phosphate dehydrogenase (E.C ); the substrate and product in the filter step are D-glucose-6-phosphate and 6-phospho-gluconic acid, respectively. (Adopted from Ref. 19 with permission). Figure Legend: From: Role of biomolecular logic systems in biosensors and bioactuators Opt. Eng. 2014;53(9): doi: /1.OE

Date of download: 7/1/2016 Copyright © 2016 SPIE. All rights reserved. A biocatalytic cascade activated by four input signals operating in sequence and resulting in NADH production, which results in electrochemical reduction/dissolution of the Fe3+-cross-linked alginate film and release of the HRP-Ab conjugate. The conjugate produces an affinity complex with the corresponding antigen (AG) and catalyzes the transformation of TMB to its oxidized state mimicking “prodrug” activation. (Reproduced from Ref. 72 with permission from The Royal Society of Chemistry). Figure Legend: From: Role of biomolecular logic systems in biosensors and bioactuators Opt. Eng. 2014;53(9): doi: /1.OE

Date of download: 7/1/2016 Copyright © 2016 SPIE. All rights reserved. The logic network equivalent to the operation of the biochemical process outlined in Fig. 4. (Reproduced from Ref. 72 with permission from The Royal Society of Chemistry). Figure Legend: From: Role of biomolecular logic systems in biosensors and bioactuators Opt. Eng. 2014;53(9): doi: /1.OE

Date of download: 7/1/2016 Copyright © 2016 SPIE. All rights reserved. (a) Optical detection of NADH production (measured as absorbance change at λ=340 nm) when inputs A to D were all applied at their logic 1 value (left bar) and in all other combinations when at least one input was applied at logic 0 value (right bar). (b) Potential generated on the PQQ-modified electrode (versus Ag/AgCl reference) when inputs A-D were all applied at their logic 1 value (left bar) and in all other combinations when at least one input was applied at logic 0 value (right bar). (c) Optically detected formation of the oxidized TMB (TMBox) (measured as absorbance change at λ=655 nm) when inputs A to F were applied at their logic 1 value (left bar) and in all other combinations when at least one input was applied at logic 0 value (right bar). (Reproduced from Ref. 72 with permission from The Royal Society of Chemistry). Figure Legend: From: Role of biomolecular logic systems in biosensors and bioactuators Opt. Eng. 2014;53(9): doi: /1.OE