Later on, Roche Diagnostics happened to be pondering the question
‘Wouldn’t it be useful to have a non-electrical version of the ion
selective electrode?’ especially for use in critical care wards where
the patients are monitored by a bank of electrical monitors. A device
with a non-electrical front end is less likely to suffer cross-talk.
Again, fluorescent PET sensors turned out to be a satisfactory answer
since they have an optical front end \cite{optimedicalcom}. Now these
fluorescent PET sensors are seeing use in ambulances so that blood
sodium levels can be determined in seconds at the scene of an injury.
What is good for a human is also good for other animals. So it is no
surprise that fluorescent PET sensors are also seeing use in veterinary
situations \cite{idexxcom}.
PLEASE INSERT ORIGINAL FIGURE HERE
Figure 2 . The world of molecular logic-based computation.
Since fluorescent PET sensors are based on rather small (ca. 1 nm)
molecules, they can enter living cells and remain undetected by the cell
machinery for reasonable periods of time. During their residence, these
molecules act as little James Bonds and gives us a window into the
private lives of protons, for instance \cite{probescom}.
Fluorescent PET sensors switch their emission signal rather sharply upon
encountering the target species, e.g. from ‘off’ to ‘on’. Such switching
of signals is similar to those seen inside computers and we made
recognized this connection between disciplines in
1993 \cite{de_Silva_1993}. The field of molecular logic-based computation
arose as a result \cite{2012,Daly_2017}. Over 610 laboratories have
joined this field (Figure 2). Many logic gate arrays of varying degrees
of small-scale integration have now been constructed. Some of these have
been operated within small spaces, some of which are alive. Since these
small spaces are not usually accessible by semiconductor logic devices,
they are virgin territory for exploration by intelligent molecular
devices.9 Even certain aspects of human behaviour can
be emulated by molecular logic-based computation
already . More progress along these lines can be
expected.
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C. P. McCoy, J. T. Rademacher and T.E. Rice, Chem. Rev. 1997,
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4. See OPTI products at optimedical.com.
5. See VETSTAT products at idexx.com.
6. See Lysosensor Blue and Lysosensor Green products at probes.com.
7. A. P. de Silva, H. Q. N. Gunaratne, C. P. McCoy, Nature 1993,
364, 42.
8. A. P. de Silva, Molecular Logic-based Computation , Royal
Society of Chemistry, Cambridge, 2013.
9. B. Daly, J. Ling, V. A. D. Silverson and A. P. de Silva, Chem.
Commun. 2015, 51 , 8403.
10. J. Ling, G. W. Naren, J. Kelly, T. S. Moody, A. P. de Silva,
J. Am. Chem. Soc. 2015 , 137 , 3763.
11. J. Ling, G. W. Naren, J. Kelly, D. B. Fox, A. P. de Silva,
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