Medicinal chemistry is integral to the drug development process, resulting in thousands of drug-like compounds synthesized yearly. Technologies like combinatorial chemistry and microwave-assisted organic synthesis have increased the speed of drug development, yet rapid purification and analytical characterization of these compounds remain a challenge.
Utilizing small sample quantities and reducing waste are key factors in cost minimization and accelerating synthesis/discover steps. Whether it is a biosimilar or larger biopharmaceutical drug or conventional small molecule synthesis, quick reaction monitoring is crucial to increase the yield (assay) and to identify and control product impurities.
Product Impurity Determination
Biosensors for Pharmacology
Electrochemical biosensors are an effective tool for therapeutic response monitoring to characterize the interactions of the drug with the target receptor, cell, or other biological systems. There are a wide variety of electrode materials available from macro electrodes down to microelectrodes and ultramicroelectrodes. Microsensor arrays have also been used for rapid, complex sensing. Biosensor selectivity can be controlled by surface functionalization with cofactors, catalytic enzymes, or other targeted organic or inorganic sites; the applied potential can also dictate the sensor’s selectivity. A wealth of literature has reported the use of electroanalytical biosensors.
Biosensors have also been applied to the study of drug pathways and metabolism for therapeutic drug monitoring (TDM). The versatility of biosensor techniques, electrodes, and surface functionalization has led to diverse applications to in-vivo, in-vitro, imaging, or fundamental biochemical experiments. Electrochemical sensors give researchers the power to control the applied waveform, and this gives rise to interesting methodologies such as time-resolved, in-situ experiments.
The engine behind a novel biosensor is a potentiostat/galvanostat. This a versatile instrument that can apply a set potential (voltage) waveform and measure the resulting current response signal resulting from charge-accumulation or charge-transfer processes at the electrode-electrolyte interface. Conversely, a current waveform can be applied to drive a charge-transfer process while measuring the resulting potential response.
There are various techniques used for biosensing that apply a constant-hold (chronoamoperomy or chronopotentiometry), sweep (linear or cyclic voltammetry), pulse (differential pulse, square-wave pulse, or others), or sequence of these waveforms. Electrochemical impedance spectroscopy (EIS), an alternating-current (AC) technique, has also been widely used to acquire in-depth information about the cell understudies such as binding events on a functionalized surface, charge-transfer resistance, multi-step reaction mechanisms, electrolyte resistance, and diffusion. Unlike source measure units, high-quality potentiostats/galvanostats have customizable capabilities such as EIS, low-current, or fast-scanning, and they have advanced software for implementing and these techniques and analyzing the data.