Sevinc Kurbanoglu

Iridium oxide nanoparticle induced dual catalytic/ inhibition based detection of phenol and pesticide compounds†

Environmental pollution control technology has a great demand for detection systems, particularly for pesticides and phenolic compounds. Moreover, analytical systems are highly required for the dual detection of different pollutants using the same platform. In that direction, a new, reliable, easy to use and disposable biosensor for the detection of catechol and chlorpyrifos is proposed. The designed biosensor with synergic properties between the high conductivity of iridium oxide nanoparticles, low-cost screen printed electrodes and the efficiency of tyrosinase shows broad linearity ranges for catechol and chlorpyrifos detection. Using this biosensor, very low limits of detection for catechol (0.08 μM) and chlorpyrifos (0.003 μM) are observed and recoveries of spiked tap and river water samples have also been studied showing very good recoveries.

Antithyroid drug detection using an enzyme cascade blocking in a nanoparticle‐based lab‐on‐a‐chip system

A methimazole (MT) biosensor based on a nanocomposite of magnetic nanoparticles (MNPs) functionalized with iridium oxide nanoparticles (IrOx NPs) and tyrosinase (Tyr) immobilized onto screen printed electrode (SPE) by using a permanent magnet is presented. This system is evaluated in batch mode via chelating copper at the active site of tyrosinase and in flow mode by thioquinone formation. The MT detection in flow mode is achieved using a hybrid polydimethylsiloxane/polyester amperometric lab-on-a-chip (LOC) microsystem with an integrated SPE. Both systems are very sensitive with low limit of detection (LOD): 0.006 μM and 0.004 μM for batch and flow modes, respectively. Nevertheless, the flow mode has advantages such as its reusability, automation, low sample volume (6 μL), and fast response (20 s). Optimization and validation parameters such as enzyme-substrate amount, flow rate, inhibition conditions, repeatability and reproducibility of the biosensor have been performed. The proposed methods have been applied in MT detection in spiked human serum and pharmaceutical dosage forms.

Electrochemically reduced graphene and iridium oxide nanoparticles for inhibition-based angiotensin-converting enzyme inhibitor detection

In this work, a novel biosensor based on electrochemically reduced graphene oxide and iridium oxide nanoparticles for the detection of angiotensin-converting enzyme inhibitor drug, captopril, is presented. For the preparation of the biosensor, tyrosinase is immobilized onto screen printed electrode by using 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-Hydroxysuccinimide coupling reagents, in electrochemically reduced graphene oxide and iridium oxide nanoparticles matrix. Biosensor response is characterized towards catechol, in terms of graphene oxide concentration, number of cycles to reduce graphene oxide, volume of iridium oxide nanoparticles and tyrosinase solution. The designed biosensor is used to inhibit tyrosinase activity by Captopril, which is generally used to treat congestive heart failure. It is an angiotensin-converting enzyme inhibitor that operates via chelating copper at the active site of tyrosinase and thioquinone formation. The captopril detections using both inhibition ways are very sensitive with low limits of detection: 0.019µM and 0.008µM for chelating copper at the active site of tyrosinase and thioquinone formation, respectively. The proposed methods have been successfully applied in captopril determination in spiked human serum and pharmaceutical dosage forms with acceptable recovery values.

Nanomedicine: An effective tool in cancer therapy

Various types of nanoparticles (NPs) have been used in delivering anticancer drugs to the site of action. This area has become more attractive in recent years due to optimal size and negligible undesirable side effects caused by the NPs. The focus of this review is to explore various types of NPs and their surface/chemical modifications as well as attachment of targeting ligands for tuning their properties in order to facilitate targeted delivery to the cancer sites in a rate-controlled manner. Heme compatibility, biodistribution, longer circulation time, hydrophilic lipophilic balance for high bioavailability, prevention of drug degradation and leakage are important in transporting drugs to the targeted cancer sites. The review discusses advantages of polymeric, magnetic, gold, and mesoporous silica NPs in delivering chemotherapeutic agents over the conventional dosage formulations along with their shortcomings/risks and possible solutions/alternatives.

Electrochemical carbon based nanosensors: A promising tool in pharmaceutical and biomedical analysis

Nanotechnology has become very popular in the sensor fields in recent times. It is thought that the utilization of such technologies, as well as the use of nanosized materials, could well have beneficial effects for the performance of sensors. Nano-sized materials have been shown to have a number of novel and interesting physical and chemical properties. Low-dimensional nanometer-sized materials and systems have defined a new research area in condensed-matter physics within past decades. Apart from the aforesaid categories of materials, there exist various materials of different types for fabricating nanosensors. Carbon is called as a unique element, due to its magnificent applications in many areas. Carbon is an astonishing element that can be found many forms including graphite, diamond, fullerenes, and graphene. This review provides an overview of some of the important and recent developments brought about by the application of carbon based nanostructures to nanotechnology for both chemical and biological sensor development and their application in pharmaceutical and biomedical area.

Simultaneous estimation and validation of some binary mixtures of antihypertensive drugs by RP-LC methods using two new generation silica columns

Two reversed phase liquid chromatographic (RP-LC) techniques are presented for the rapid, accurate, precise, simultaneous determination of olmesartan-hydrochlorothiazide and zofenopril-hydrochlorothiazide binary mixtures in their dosage forms. The separation of these binary mixtures was carried out by using two new stationary phases that have different surface chemistries which were used for the first time in the determination of these binary mixtures. The analyte peaks were detected at 216 nm. Linearity was obtained in different concentration ranges between 0.5 and 20 μg mL(-1) for all compounds. The proposed methods have been extensively validated and sample preparation, flow rate, run time of the analytical systems were at low levels. The proposed methods would decrease the consumption of organic solvents and reagents further safeguarding to our environment.

Simultaneous determination and validation of some binary mixtures of antihypertensive drugs using ratio derivative spectrophotometric method

Ratio derivative spectrophotometric technique is presented for the rapid, accurate and precise simultaneous determination of olmesartan medoxomil (OLM), hydrochlorothiazide (HCT), and zofenopril (ZOF) as well as HCT binary mixtures in their dosage forms. First derivative of the ratio spectra (DD1) by measurements using different amplitudes was used and calibration graphs were established for 0.5–12 mg/mL HCT and 0.5–20 mg/mL OLM and ZOF. This method depends on first derivative of the ratio spectra by division of the absorption spectrum of the binary mixture by a standard spectrum of one of the components and then calculating the first derivative of the ratio spectrum. The first derivative of the ratio amplitudes at 250.4 and 291.5 nm for OLM, 250.4 and 298.1 nm for ZOF and 231.8, 332.2, 232.3 and 280.4 nm for HCT were selected for the determination. The proposed methods were successfully applied for determining of both drug combinations (ZOF-HCT and OLM-HCT) in their synthetic mixtures and in pharmaceutical dosage forms. The described procedures are extensively validated, non-destructive and do not require any separation steps.

DEVELOPMENT AND VALIDATION OF A STABILITY-INDICATING RP-LC METHOD FOR THE DETERMINATION OF ANTICANCER DRUG EPIRUBICIN IN PHARMACEUTICALS

In the present paper, sensitive, rapid, and different analytical methodology was developed for the determination of anticancer drug epirubicin (EPR). The mixture of epirubicin and moxifloxacin as internal standard was separated on a reversed phase Waters Spherisorb ODS1 column (250mm × 4.6mm × 5mm) using acetonitrile/water (30:70 v/v) mixture containing 15 mM phosphoric acid as mobile phase at 0.6 mL min−1 flow rate and 30 C. Also degradation studies were conducted as stress conditions of UV light, acidic hydrolysis, alkaline hydrolysis, oxidation, and heat in oven (100°C), to evaluate the ability of the proposed method for the separation of EPR from its degradation products. The validated method suggests routine analysis of EPR in differently equipped laboratories.

Nanobiodevices for electrochemical biosensing of pharmaceuticals

Abstract Nanobiodevices are analytical devices for the analysis, detection, quantification, or monitoring of pharmaceuticals. Nanobiodevices have gained a great deal of importance, due to their advantages in terms of response speed, low cost, portability, small sample and reagent consumption, and low energy requirements. The combination of sensing molecules that are in part biorecognition, and part transducer is the main aspect of biosensors. The choice of suitable matrix, monitoring/quantifying the interactions between the analytes, and the biorecognition part is very important in designing biosensors. In this chapter, nanobiodevices for electrochemical biosensing of pharmaceuticals related to different biorecognition parts, such as enzymes, DNA, tissues, bacteria, yeast, antibodies, antigens, liposomes, and organelles will be discussed. Nanobiodevices, such as lab-on-a-chip platforms in biosensors, and their applications in pharmaceutical analysis will also be discussed.

Current perspectives on drug release studies from polymeric nanoparticles

Abstract In vitro drug release testing is an important tool in drug development; it facilitates comparing the performance of different formulations and enables choosing the most suitable formulation. Polymeric nanoparticles (NPs), such as poly(lactic-co-glycolic acid), chitosan, poly(methyl methacrylate), etc., are colloidal systems that have been the focus of extensive investigations. Biomedical applications of polymeric NPs have been considered in numerous areas of medicine, due to their ability to control drug release and distribution, as well as their biodegradability. Especially for poorly water-soluble drug incorporated NPs, drug release study design affects release time and sink conditions. For drug-loaded polymeric NPs, pharmacopoeial dissolution apparatuses are not commonly used, due to unsuitability of both the paddle and basket apparatus. Nonuniform hydrodynamics and fluctuations in the dissolution rate measurements limit dissolution tests. Due to lack of an official test, some methods using orbital shaker, magnetic stirrer, and flow-through cell, etc., with or without dialysis bag, are offered. In this chapter, commonly used methods for polymeric NP drug release studies are explained from the view point of NP characteristics, dissolution medium, apparatus, and biomedical applications.