Nano optical and electrochemical sensors and biosensors for detection of narrow therapeutic index drugs

For the first time, a comprehensive review is presented on the quantitative determination of narrow therapeutic index drugs (NTIDs) by nano optical and electrochemical sensors and biosensors. NTIDs have a narrow index between their effective doses and those at which they produce adverse toxic effects. Therefore, accurate determination of these drugs is very important for clinicians to provide a clear judgment about drug therapy for patients. Routine analytical techniques have limitations such as being expensive, laborious, and time-consuming, and need a skilled user and therefore  the nano/(bio)sensing technology leads to high interest.

Carbon based nanomaterials for the detection of narrow therapeutic index pharmaceuticals

Precise detection of important pharmaceuticals with narrow therapeutic index (NTI) is very critical as there is a small window between their effective dose and the doses at which the adverse reactions are very likely to appear. Regarding the fact that various pharmacokinetics will be plausible while considering pharmacogenetic factors and also differences between generic and brand name drugs, accurate detection of NTI will be more important. Current routine analytical techniques suffer from many drawbacks while using novel biosensors can bring up many advantages including fast detection, accuracy, low cost with simple and repeatable measurements. Recently the well-known carbon Nano-allotropes including carbon nanotubes and graphenes have been widely used for development of different Nano-biosensors for a diverse list of analytes because of their great physiochemical features such as high tensile strength, ultra-light weight, unique electronic construction, high thermo-chemical stability, and an appropriate capacity for electron transfer. Because of these exceptional properties, scientists have developed an immense interest in these nanomaterials. In this case, there are important reports to show the effective Nano-carbon based biosensors in the detection of NTI drugs and the present review will critically summarize the available data in this field.

Chemical analysis in saliva and the search for salivary biomarkers – a tutorial review

A review of the uses of saliva biomarkers, detection methods and requirements for new biomarkers.

Fluorescence Probe Based on an Amino-Functionalized Fluorescent Magnetic Nanocomposite for Detection of Folic Acid in Serum

A new fluorescence probe constructed with a multifunctional nanocomposite, Fe₃O₄-ZnS:Mn²⁺/SiO₂-NH₂, was successfully synthesized and then used to detect folic acid in real serum samples. The nanocomposite was characterized by fluorescence spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, and physical property measurement system. With the addition of analyte, the Fe₃O₄-ZnS:Mn²⁺/SiO₂-NH₂ composite and folic acid formed a new complex because cross-linking of the amino and carboxyl groups participated in the condensation reaction. Then, the energy of quantum dots was transferred to the complex and led to quenching of the fluorescence. Moreover, the fluorescence intensity decreased significantly as the concentration of folic acid increased, and the fluorescence quenching ratio F₀/F was related to the folic acid concentration in the range from 0.1 to 5 μg mL^-1. This method was used for detecting folic acid in real serum samples and gave recoveries in the range of 89.0%-96.0%, with relative standard deviations of 1.2%-3.9%. The detection limit was 9.6 ng mL^-1 (S/N = 3). These satisfactory and simple results showed the great potential of this fluorescence probe in the field of pharmaceutical analysis.

Molecularly imprinted poly(4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid) modified glassy carbon electrode as an electrochemical theophylline sensor

Theophylline is an inexpensive drug employed in asthma and chronic obstructive pulmonary disorder medications and is toxic at higher concentration. The development of a molecularly imprinted polymer based theophylline electrochemical sensor on glassy carbon electrode by the electropolymerization of 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid is being discussed in this work. The MIP modification enhances the theophylline recognition ability and the electron transfer kinetics of the bare electrode. The parameters, controlling the performance of the imprinted polymer based sensor, like number of electropolymerization cycles, composition of the pre-polymerization mixture, pH and immersion time were investigated and optimized. The interaction energy and the most stable conformation of the template-monomer complex in the pre-polymerization mixture were determined computationally using ab initio calculations based on density functional theory. The amperometric measurements showed that the developed sensor has a method detection limit of 0.32μM for the dynamic range of 0.4 to 17μM, at optimized conditions. The transducer possesses appreciable selectivity in the presence of structurally similar interferents such as theobromine, caffeine and doxofylline. The developed sensor showed remarkable stability and reproducibility and was also successfully employed in theophylline detection from commercially available tablets.

Quantum dots (QDs) based fluorescence probe for the sensitive determination of kaempferol

In this work, using the quenching of fluorescence of thioglycollic acid (TGA)-capped CdTe quantum dots (QDs), a novel method for the determination of kaempferol (KAE) has been developed. Under optimum conditions, a linear calibration plot of the quenched fluorescence intensity at 552nm against the concentration of KAE was observed in the range of 4-44μgmL(-1) with a detection limit (3σ/K) of 0.79μgmL(-1). In addition, the detailed reaction mechanism has also been proposed on the basis of electron transfer supported by ultraviolet-visible (UV-vis) absorption and fluorescence (FL) spectroscopy. The method has been applied for the determination of KAE in pharmaceutical preparations with satisfactory results. The proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation.

A simple, but highly sensitive, graphene-based voltammetric sensor for salvianic acid A sodium

A simple, but highly sensitive, electrochemical sensor for the determination of salvianic acid A sodium (SAS) based on reduced graphene oxide (rGO) is reported. The sensor (rGO/GCE(ox)) was prepared by coating an rGO film on the surface of a pre-anodized glassy carbon electrode (GCE(ox)) through a dipping-drying method. The characteristic of the modified electrode was examined by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Compared with bare GCE, GCE(ox) and rGO modified GCE, this sensor exhibited a superior ability for detecting SAS. Under the selected conditions, the reduction current had a good linear relationship with the SAS concentration in the range of 8.0 × 10(-8) - 2.0 × 10(-5) mol L(-1), with a low detection limit of 2.0 × 10(-8) mol L(-1). Furthermore, the method was also successfully applied to detect SAS in medicinal tablets.