Background:
The determination of drugs in pharmaceutical formulations and human biologic fluids is
important for pharmaceutical and medical sciences. Successful analysis requires low sensitivity, high selectivity
and minimum interference effects. Current analytical methods can detect drugs at very low levels but these methods
require long sample preparation steps, extraction prior to analysis, highly trained technical staff and high-cost
instruments. Biosensors offer several advantages such as short analysis time, high sensitivity, real-time analysis,
low-cost instruments, and short pretreatment steps over traditional techniques. Biosensors allow quantification not
only of the active component in pharmaceutical formulations, but also the degradation products and metabolites in
biological fluids. The present review gives comprehensive information on the application of biosensors for drug
discovery and analysis. Moreover, this review focuses on the fabrication of these biosensors.
Methods:
Biosensors can be classified as the utilized bioreceptor and the signal transduction mechanism. The classification
based on signal transductions includes electrochemical optical, thermal or acoustic. Electrochemical and
optic transducers are mostly utilized transducers used for drug analysis. There are many biological recognition elements,
such as enzymes, antibodies, cells that have been used in fabricating of biosensors. Aptamers and antibodies
are the most widely used recognition elements for the screening of the drugs. Electrochemical sensors and biosensors
have several advantages such as low detection limits, a wide linear response range, good stability and reproducibility.
Optical biosensors have several advantages such as direct, real-time and label-free detection of many
biological and chemical substances, high specificity, sensitivity, small size and low cost. Modified electrodes enhance
sensitivity of the electrodes to develop a new biosensor with desired features. Chemically modified electrodes
have gained attention in drug analysis owing to low background current, wide potential window range, simple
surface renewal, low detection limit and low cost. Modified electrodes produced by modifying of a solid surface
electrode via different materials (carbonaceous materials, metal nanoparticles, polymer, biomolecules) immobilization.
Recent advances in nanotechnology offer opportunities to design and construct biosensors. Unique features
of nanomaterials provide many advantages in the fabrication of biosensors. Nanomaterials have controllable
chemical structures, large surface to volume ratios, functional groups on their surface. To develop proteininorganic
hybrid nanomaterials, four preparation methods have been used. These methods are immobilization, conjugation,
crosslinking and self-assembly. In the present manuscript, applications of different biosensors, fabricated
by using several materials, for drug analysis are reviewed. The biosensing strategies are investigated and discussed
in detail.
Results:
Several analytical techniques such as chromatography, spectroscopy, radiometry, immunoassays and electrochemistry
have been used for drug analysis and quantification. Methods based on chromatography require timeconsuming
procedure, long sample-preparation steps, expensive instruments and trained staff. Compared to chromatographic
methods, immunoassays have simple protocols and lower cost. Electrochemical measurements have
many advantages over traditional chemical analyses and give information about drug quantity, metabolic fate of
drugs, and pharmacological activity. Moreover, the electroanalytical methods are useful to determine drugs sensitively
and selectivity. Additionally, these methods decrease analysis cost and require low-cost instruments and
simple sample pretreatment steps.
Conclusion:
In recent years, drug analyses are performed using traditional techniques. These techniques have a
good detection limit, but they have some limitations such as long analysis time, expensive device and experienced
personnel requirement. Increased demand for practical and low-cost analytical techniques biosensor has gained interest
for drug determinations in medical sciences. Biosensors are unique and successful devices when compared to
traditional techniques. For drug determination, different electrode modification materials and different biorecognition
elements are used for biosensor construction. Several biosensor construction strategies have been developed to
enhance the biosensor performance. With the considerable progress in electrode surface modification, promotes the
selectivity of the biosensor, decreases the production cost and provides miniaturization. In the next years, advances
in technology will provide low cost, sensitive, selective biosensors for drug analysis in drug formulations and biological
samples.
Sensor Applications in Analysis of Drugs and Formulations