analyzer, a benchtop instrument, was launched by Yellow Springs (Ohio, USA),
between 1973 and 1975. In the late 80s and early 90s, several hand-held devices for
glycemic control were successively commercialized, with a huge impact in the
clinical diagnosis of diabetes mellitus. These point-of-care tests (POCT) are quick
and easy to use, even by non-trained personal, enabling self-site monitoring of
blood glucose levels [2, 3].
The concept of enzyme electrodes was further expanded to other biological
materials, such as nucleic acids, antibodies, whole cells, and tissue slices. On the
other hand, due to the rapid technological evolution that has taken place in the
chemical sensors area, the concept of biosensing soon embraced a plethora of other
transducing platforms, ranging from potentiometric and conductometric methods to
optical, piezoelectric, thermometric, magnetic, and micromechanical techniques.
The modern biosensing field has now reached a vast frontier of interdisciplinary
R&D that combines biology, analytical chemistry, materials sciences, physics,
electronics, and software programming, finding wide applications in biomedical
research, food safety, process control, environmental monitoring, defense, and
forensic analysis [1–3]. Nonetheless, the clinical diagnostics segment still dominates the market, where we can find the biggest opportunities, such as the glucose
meters for diabetic patients. In 2019, the global biosensors market was valued at
$21.2 billion, and is expected to grow in the next five years at a Compound Annual
Growth Rate (CAGR) of 8.3% [4], fueled, in part, by the increasing demand for
point-of-use testing in the medical diagnosis, and mandated control and monitoring
in the industrial, and environmental sectors [1].
Electrochemical biosensors captured the largest market share, owing to their
widespread applications, good analytical performance (wide linear response range,
low detection limits, accuracy, reproducibility, long-term stability), independence
from sample turbidity, low-cost, simplicity, robustness, portability, disposability,
low power consumption, and compatibility with new microfabrication technologies
[1, 5] and the fourth industrial revolution. This class of biosensors also dominates
the R&D space, closely followed by optical biosensors. Enzyme electrochemical
biosensors, in particular, keep a leading position. Among the over forty thousand
documents published under the topic of “Biosensors” (data retrieved from the
abstract & citation database Scopus, on 26th May 2020), about a third of all entries
match the keywords “enzyme” and “electrode”. This is mainly due to the selectivity
of detection usually conveyed by these biological catalysts, the easier access to
different enzyme sources with broad catalytic activities, the facility in transducing
the analyte recognition event, and the advances in protein engineering tools, which
allow the customized modulation of the enzyme structural and activity features.
In this chapter, we aim at describing the main works concerning the development
of enzyme biosensors, giving special emphasis to those based on electrochemical
transducing systems. One should mention that all bioanalytical systems not
including a physical transducer, i.e., where the output signal is not in the electric
format (e.g., colorimetric test kits or lateral flow tests based on color visualization)
were excluded from this review since they do not fall in the biosensors category.
Among the different families of enzymes explored up to today, we will address the
Selective Enzymes at the Core of Advanced Electroanalytical …
305
between 1973 and 1975. In the late 80s and early 90s, several hand-held devices for
glycemic control were successively commercialized, with a huge impact in the
clinical diagnosis of diabetes mellitus. These point-of-care tests (POCT) are quick
and easy to use, even by non-trained personal, enabling self-site monitoring of
blood glucose levels [2, 3].
The concept of enzyme electrodes was further expanded to other biological
materials, such as nucleic acids, antibodies, whole cells, and tissue slices. On the
other hand, due to the rapid technological evolution that has taken place in the
chemical sensors area, the concept of biosensing soon embraced a plethora of other
transducing platforms, ranging from potentiometric and conductometric methods to
optical, piezoelectric, thermometric, magnetic, and micromechanical techniques.
The modern biosensing field has now reached a vast frontier of interdisciplinary
R&D that combines biology, analytical chemistry, materials sciences, physics,
electronics, and software programming, finding wide applications in biomedical
research, food safety, process control, environmental monitoring, defense, and
forensic analysis [1–3]. Nonetheless, the clinical diagnostics segment still dominates the market, where we can find the biggest opportunities, such as the glucose
meters for diabetic patients. In 2019, the global biosensors market was valued at
$21.2 billion, and is expected to grow in the next five years at a Compound Annual
Growth Rate (CAGR) of 8.3% [4], fueled, in part, by the increasing demand for
point-of-use testing in the medical diagnosis, and mandated control and monitoring
in the industrial, and environmental sectors [1].
Electrochemical biosensors captured the largest market share, owing to their
widespread applications, good analytical performance (wide linear response range,
low detection limits, accuracy, reproducibility, long-term stability), independence
from sample turbidity, low-cost, simplicity, robustness, portability, disposability,
low power consumption, and compatibility with new microfabrication technologies
[1, 5] and the fourth industrial revolution. This class of biosensors also dominates
the R&D space, closely followed by optical biosensors. Enzyme electrochemical
biosensors, in particular, keep a leading position. Among the over forty thousand
documents published under the topic of “Biosensors” (data retrieved from the
abstract & citation database Scopus, on 26th May 2020), about a third of all entries
match the keywords “enzyme” and “electrode”. This is mainly due to the selectivity
of detection usually conveyed by these biological catalysts, the easier access to
different enzyme sources with broad catalytic activities, the facility in transducing
the analyte recognition event, and the advances in protein engineering tools, which
allow the customized modulation of the enzyme structural and activity features.
In this chapter, we aim at describing the main works concerning the development
of enzyme biosensors, giving special emphasis to those based on electrochemical
transducing systems. One should mention that all bioanalytical systems not
including a physical transducer, i.e., where the output signal is not in the electric
format (e.g., colorimetric test kits or lateral flow tests based on color visualization)
were excluded from this review since they do not fall in the biosensors category.
Among the different families of enzymes explored up to today, we will address the
Selective Enzymes at the Core of Advanced Electroanalytical …
305