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Combinatorial Chemistry &
High Throughput Screening
ISSN: 1386-2073
Combinatorial Chemistry &
High Throughput Screening
Volume 10, Number 7, August 2007
Contents
Supramolecular Devices for the High-Throughput Screening
of Drugs, Nutrients and Metabolites in Postgenomic Era (Part
3)
Guest Editor: Grzegorz Bazylak
Editorial Pp.
493-494
Review Articles
Solid Electrodes in Electroanalytical Chemistry: Present
Applications and Prospects for High Throughput Screening of
Drug Compounds Pp. 495-513
Bengi Uslu and Sibel A. Ozkan
[Abstract]
Voltammetric Insights in the Transfer of Ionizable
Drugs Across Biomimetic Membranes - Recent Achievements
Pp. 514-526
Rubin Gulaboski, Fernanda Borges, Carlos M. Pereira, M.
Natália D.S. Cordeiro, Jorge Garrido and A. Fernando
Silva
[Abstract]
Ion Recognition: Application of Symmetric and Asymmetric
Schiff Bases and Their Complexes for the Fabrication of Cationic
and Anionic Membrane Sensors to Determine Ions in Real Samples
Pp. 527-546
Farnoush Faridbod, Mohammad Reza Ganjali, Rassoul Dinarvand
and Parviz Norouzi
[Abstract]
Electrochemical Detection Coupled with High-Performance
Liquid Chromatography in Pharmaceutical and Biomedical Analysis:
A Mini Review Pp. 547-554
Chengyin Wang, Jianyun Xu, Guiyou Zhou, Qishu Qu, Gongjun
Yang and Xiaoya Hu
[Abstract]
Research Articles
Response of DNA Fragments to Potentiometric Sensors Studied
Using HPLC Pp. 555-559
Luc J. Nagels, Joseph Everaert, Hugo Bohets, Jurgen Del
Favero, Dirk Goossens, Johan Robbens, Marek Pietraszkiewicz
and Oksana Pietraszkiewicz
[Abstract]
Potentiometric Sensors Enabling Fast Screening of
the Benign Prostatic Hyperplasia Drug Alfuzosin in Pharmaceuticals,
Urine and Serum Pp. 560-570
Vinod K. Gupta, Ashok K. Singh and Barkha Gupta
[Abstract]
Investigation of Electrochemical Behavior of Lipid
Lowering Agent Atorvastatin Calcium in Aqueous Media and its
Determination from Pharmaceutical Dosage Forms and Biological
Fluids Using Pp. 571-582
Boron-Doped Diamond and Glassy Carbon Electrodes Burcu
Dogan-Topal, Bengi Uslu and Sibel A. Ozkan
[Abstract]
Potentiometric Sensor for the High Throughput Determination
of Tetramisole Hydrochloride Pp. 583-594
Vinod K. Gupta, Ashok K. Singh and Barkha Gupta
[Abstract]
Voltammetric Determination of Sinomenine in Biological
Fluid Using a Glassy Carbon Electrode Modified by a Composite
Film of Polycysteic Acid and Carbon Nanotubes Pp.
595-603
Chengyin Wang, Jun Guan, Qishu Qu, Gongjun Yang and Xiaoya
Hu
[Abstract]
Polymeric Liquid Membrane Electrodes Incorporated
with Undecylcalix[4]-Resorcinarene for Screening of Neutral
Forms of Diaminobenzene Isomers Pp. 604-610
Katarzyna Kurzatkowska, Hanna Radecka, Wim Dehaen, Michal
Wasowicz, Izabela Grzybowska and Jerzy Radecki
[Abstract]
Analysis of Metformin Dosage Formulations by Capillary
Electrophoresis at Nano Scale Detection Pp. 611-615
Imran Ali, Hassan Y. Aboul-Enein and Vinod K. Gupta
[Abstract]
Meet the Guest Editor
Pp. 616
Abstracts
[Back to top]
Editorial
The growing need for microfluidic systems in high throughput
screening (HTS) urgently demands the development of compatible
detection systems, especially for the analysis of non-labeled
and ionizable analytes. Direct detection employing electrochemical
processes offers remarkable advantages such as reduced cost,
low power requirements, enhanced portability, independence
of sample turbidity, subnanomolar sensitivity, reproducibility,
and compatibility with micromachining and microfabrication
procedures. More than 70% of current drugs are ionizable under
physiological conditions and have the potential to be measured
using electrochemical detection. The papers in Part 3 of this
special issue of Combinatorial Chemistry & High Throughput
Screening summarize and highlight some recent advances,
directions and key concepts in the development of new supramolecular
electrode materials, ion recognition modes, detection schemes,
operational principles, applications and future prospects
for electrochemical HTS devices and sensors.
The review by Uslu and Ozkan opening this issue presents the
status and recent achievements in the use of native and chemically
modified solid noble metal and carbon nanotube electrodes
for HTS of drugs and pharmacologically active compounds. In
addition, the review by Gulaboski et al. describes
the use of new four-electrode and three-phase electrode voltammetry
at the interface of immiscible electrolyte solutions mimicking
biomembrane systems which enables precise determination of
unknown standard partition coefficients for ionized drugs-of-abuse,
peptides, nutrients, and examples of ubiquitous environmental
pollutants. Similarly, Ganjali et al., review the
use of podand, macrocycle or transition metal complexed Schiff
bases as highly selective ionophores in the construction of
disposable electrodes for HTS of inorganic cations and anions,
as well as ionizable drugs and nutrients. In the minireview
by Wang et al., recent progress is discussed concerning
the sensitive and specific electrochemical detection of drugs
and their metabolites under the continuous flow conditions
of HPLC or ultra-fast flow-injection analysis.
The practical implementation and unique properties of lipophilic
podand ionophore supported potentiometric detection in the
construction of DNA sensitive arrays coupled with HPLC is
reported in the research paper by Nagels et al. In
addition, the construction and characteristics of lipophilic
calix[4]resorcinarene based potentiometric sensor enabling
selective determination of positional isomers of phenylenediamine
type endocrine disrupting agents and allergens are reported
in the paper by Radecki et al. Spectacular examples
of selective electrochemical determination of drugs used in
mono and combined therapies of metabolic, degenerative and
infectious human diseases such as a non-insulin-dependent
diabetes mellitus, beginning prostatic hyperplasia, atherosclerosis,
rheumatoid arthritis, and ascariasis are described in the
series of research papers by Gupta et al., Dogan-Topal
et al., Wang et al., and Aboul-Enein et
al. Innovative potentiometric and voltammetric procedures
were developed and described in these research papers using
a boron doped diamond, a carbon nanotubes and liquid membrane
electrodes. By reducing the size of such working electrodes,
it will be possible to enhance their performance and sensitivity
even further. Thus, it is quite reasonable to say that complete
self-contained HTS microsystems equipped with electrochemical
detection may be realized soon through an on-chip and proteochip
integration of the potentiostatic circuitry with supramolecular
versions of nanovalves, switchers, transducers, digital multiplexers,
logic networks, sequential and combinational circuits as well
as memory that mimic the operation of currently used semiconductor
logic gates. Hoping that our publishing efforts will help
transform such promising views into reality, I would like
to extend my grateful thanks, as the Guest Editor of this
special issue of Combinatorial Chemistry & High Throughput
Screening, to all authors who kindly contributed in all
three parts of this exceptional project.
Grzegorz Bazylak
Department of Pharmaco-Bromatology & Molecular Nutrition
Faculty of Pharmacy, Collegium Medicum
Nicolaus Copernicus University
PL-85067 Bydgoszcz
Poland
E-mail: gbazylak@cm.umk.pl
[Back to top]
Solid Electrodes in Electroanalytical Chemistry: Present
Applications and Prospects for High Throughput Screening of
Drug Compounds
Bengi Uslu and Sibel A. Ozkan
This review summarizes recent progress in the development
and application of solid electrodes to the screening of pharmaceutical
dosage forms and biological fluids. Recent trends and advances
in the electroanalytical chemistry of solid electrodes, microelectrodes
and electrochemical sensors are reviewed. The varieties of
solid electrodes and their basic physico-chemical properties
and some specific characteristics including some supramolecular
phenomena at their surface are surveyed. This review also
includes some selected designs and their applications. Despite
many reviews about individual solid electrodes in the literature,
this review offers the first comprehensive report on all forms
of solid electrodes. Special attention is paid to the possibilities
of solid electrodes in high throughput electroanalytical investigation
of drug dosage forms and biological samples using modern electroanalytical
techniques. Various selected studies on these subjects since
1996 are reviewed in this paper.
[Back to top]
Voltammetric Insights in the Transfer of Ionizable
Drugs Across Biomimetic Membranes - Recent Achievements
Rubin Gulaboski, Fernanda Borges, Carlos M. Pereira, M.
Natália D.S. Cordeiro, Jorge Garrido and A. Fernando
Silva
The latest results of voltammetric research on the ionic transfer
process of ionisable drugs across bare and lipid-modified
liquid-liquid interfaces are reviewed. In recent years, two
voltammetric methods have been extensively applied to this
purpose, i.e. the classical four electrode voltammetry at
the interface between two immiscible electrolyte solutions,
and the “three-phase electrode.” Thus, a brief
background of the methodologies and some successful examples
of their application are highlighted in this work. Particular
attention is given to the ionic transfer kinetics and to the
electro-chemical characterization of the drug-membrane interactions
between the ionized drugs and lipid-modified interfaces. Future
trends in this area are also mentioned in connection with
high-throughput assessment of ADMET properties of drugs.
[Back to top]
Ion Recognition: Application of Symmetric and Asymmetric
Schiff Bases and Their Complexes for the Fabrication of Cationic
and Anionic Membrane Sensors to Determine Ions in Real Samples
Farnoush Faridbod, Mohammad Reza Ganjali, Rassoul Dinarvand
and Parviz Norouzi
Schiff base compounds refer to the branch of supra-molecules
and can be used as sensing material in the construction of
potentiometric ion selective electrodes (ISEs). This relatively
modern field has been subject to extensive research in the
period of 1999-2007 when more than 100 ISEs employing Schiff
bases were constructed. The quantitative high-throughput detection
of 29 cations and 7 anions has been demonstrated in various
scientific branches, such as bio-medicine, pharmacy, biochemistry,
pharmacology, environmental chemistry, food technology, and
agriculture. This review discusses Schiff base compounds and
their applications in the design and development of ion selective
sensors and microsensors.
[Back to top]
Electrochemical Detection Coupled with High-Performance
Liquid Chromatography in Pharmaceutical and Biomedical Analysis:
A Mini Review
Chengyin Wang, Jianyun Xu, Guiyou Zhou, Qishu Qu, Gongjun
Yang and Xiaoya Hu
Recent advances in electrochemical detection techniques coupled
with high-performance liquid chromatography (HPLC-ECD) in
pharmaceutical and biomedical analysis are reviewed. ECD classification
and modes including common amperometric, coulometric, conductimetric,
and potentiometric detector, are outlined and the some typical
examples of determinations in pharmaceutical and biomedical
analysis are described. The electrochemical detection system
can offer superior merits over other detectors commonly used
with HPLC. These techniques have great potential owing to
their prominent characteristics in high-throughput screening
procedures of drugs in various matrices. Fundamental 67 references
from last 5 years related with a field are cited in this review.
[Back to top]
Response of DNA Fragments to Potentiometric Sensors Studied
Using HPLC
Luc J. Nagels, Joseph Everaert, Hugo Bohets, Jurgen Del
Favero, Dirk Goossens, Johan Robbens, Marek Pietraszkiewicz
and Oksana Pietraszkiewicz
Potentiometric sensors are studied as viable candidates for
the construction of high throughput DNA arrays. For preliminary
investigations, such sensors were used in an HPLC setup in
the present work. This avoided errors due to ionic contaminants
or additives in the commercial samples. The oligonucleotides
dT10, dT20
and dT30 were used as test
substances. The potentiometric sensors were of the coated
wire type, containing PVC, DOP, MTDDACl and a synthetic podand
urea receptor. The HPLC system consisted of a reversed phase
column eluted with a phosphate buffer, triethylam-moniumacetate
(TEAA), and an acetonitrile gradient. Molar responses and
sensitivities increased with increasing chain length of oligonucleotides,
yielding detection limits as low as10-6M
(dT30, injected concentration).
The slopes of the calibration graphs were at least 23 mV/decade
(dT10), which was much higher
than expected. The results are discussed in view of the potential
use of this sensor type in high throughput microarrays.
[Back to top]
Potentiometric Sensors Enabling Fast Screening of
the Benign Prostatic Hyperplasia Drug Alfuzosin in Pharmaceuticals,
Urine and Serum
Vinod K. Gupta, Ashok K. Singh and Barkha Gupta
The construction and characterization of potentiometric membrane
electrodes are described for the quantification of alfuzosin,
a drug used in a mono- and combined therapy of benign prostatic
hyperplasia (BPH). The membranes of these electrodes consist
of alfuzosin hydrochloride-tetraphenyl borate, (Az-TPB), chlorophenyl
borate (Az-ClPB), and phosphotungstate (Az3-PT)
ion associations as molecular recognition reagent dispersed
in PVC matrix with dioctylpthalate as plasticizer. The performance
characteristics of these electrodes, which were evaluated
according to IUPAC recommendations, revealed a fast, stable
and liner response for alfuzosin over the concentration ranges
of 8.3 ×
10-6 to 1.0 ×
10-2 M, 3.8 ×
10-6 to 1.0 ×
10-2 M, 7.5 ×
10-7 to 1.0 ×
10-2 M AzCl with cationic
slopes of 57.0, 56.0 and 58.5 mV/decade, respectively. The
solubility product of the ion-pair and the formation constant
of the precipitation reaction leading to the ion-pair formation
were determined conductometrically. The electrodes, fully
characterized in terms of composition, life span and usable
pH range, were applied to the potentiometric determination
of alfuzosin hydrochloride ion in different pharmaceutical
preparations and biological fluids without any interference
from excipients or diluents commonly used in drug formulations.
The potentiometric method was also used in the determination
of alfuzosin hydrochloride in pharmaceutical preparations
in four batches with different expiration dates. Validation
of the method showed suitability of the proposed electrodes
for use in the quality control assessment of alfuzosin hydrochloride.
This potentiometric method offers the advantages of high–throughput
determination, simplicity, accuracy, automation feasibility,
and applicability to turbid and colored sample solutions.
[Back to top]
Investigation of Electrochemical Behavior of Lipid
Lowering Agent Atorvastatin Calcium in Aqueous Media and its
Determination from Pharmaceutical Dosage Forms and Biological
Fluids Using
Boron-Doped Diamond and Glassy Carbon Electrodes Burcu
Dogan-Topal, Bengi Uslu and Sibel A. Ozkan
The electrochemical behavior of atorvastatin calcium at glassy
carbon and boron-doped diamond electrodes has been studied
using voltammetric techniques. The possible mechanism of oxidation
was discussed with model compounds. The dependence of the
peak current and potentials on pH, concentration, scan rate
and nature of the buffer were investigated for both electrodes.
The oxidation of atorvastatin was irreversible and exhibited
a diffusion-controlled fashion on the diamond electrode. A
linear response was obtained within the range of 9.65 ×
10-7 - 3.86 × 10-5
M in 0.1 M H2SO4
solution for both electrodes. The detection limits of a standard
solution are estimated to be 2.11 × 10-7
M with differential pulse voltammetry (DPV) and 2.05 ×
10-7M with square wave voltammetry
(SWV) for glassy carbon electrode, and 2.27 × 10-7
M with DPV and 1.31 × 10-7M
with SWV for diamond electrodes in 0.1 M H2SO4
solution. The repeatability of the methods was found good
for both electrodes. The methods were fully validated and
successfully applied to the high-throughput determination
of the drug in tablets, human serum and human urine with good
recoveries.
[Back to top]
Potentiometric Sensor for the High Throughput Determination
of Tetramisole Hydrochloride
Vinod K. Gupta, Ashok K. Singh and Barkha Gupta
The electrochemical response characteristics of poly(vinyl)chloride
(PVC) based membrane sensors for determination of tetramisole
hydrochloride (TmCl) is described. The membranes of these
electrodes consist of tetramisole-tetraphenyl borate (Tm-TPB),
chlorophenyl borate (Tm-ClPB), and phosphotungstate (Tm3-PT)
ion associations dispersed in a PVC matrix with dibutylpthalate
as a plasticizer. The electrodes were fully characterized
in terms of composition, life span, usable pH range, and working
concentration range and ionic strength. The electrodes showed
Nernstian response over the concentration ranges of 7.4 ×
10-7 to 1.0×10-2
M, 1.7 ×
10-6 to 1.0×10-2
M, and 5.6 ×
10-6 to 1.0×10-2
M TmCl, respectively, and were applied to the potentiometric
determination of tetramisole ion in pure solutions and pharmaceutical
preparations. The potentiometric determination was also used
in the determination of tetramisole in pharmaceutical preparations
in four batches of different expiration dates. The electrodes
exhibited good selectivity for TmCl with respect to a large
number of excipients such as inorganic cations, organic cations,
amino acids, and sugars. The solubility product of the ion-pair
and the formation constant of the precipitation reaction leading
to the ion-pair formation were determined conductometrically.
The new potentiometric method offers the advantages of high–throughput
determination, simplicity, accuracy, automation feasibility,
and applicability to turbid and colored sample solutions.
[Back to top]
Voltammetric Determination of Sinomenine in Biological
Fluid Using a Glassy Carbon Electrode Modified by a Composite
Film of Polycysteic Acid and Carbon Nanotubes
Chengyin Wang, Jun Guan, Qishu Qu, Gongjun Yang and Xiaoya
Hu
Polycysteic acid based electrochemical oxidation of L-cysteine
(CySH) and carbon nanotubes (CNTs) formed a composite thin
film material at a glassy carbon electrode (GCE) that was
used a novel modifier for electroanalytical determination
of sinomenine which is used for rheumatoid arthritis treatment.
The determination of sinomenine at the composite modified
electrode was studied by differential pulse voltammetry (DPV).
The peak current obtained at + 0.632 V (vs SCE) from
DPV was linearly dependent on the sinomenine concentration
in the range of 1.0 × 10-7
to 6.0 × 10-5 M in
a B-R buffer solution (0.04 M, pH 1.81) with a correlation
coefficient of 0.998. The detection limit (S/N = 3) was 5.0
× 10-8 M. The electrochemical
reaction mechanism of sinomenine was also discussed. This
new method was then applied to the high-throughput determination
of sinomenine in human serum samples with satisfactory results.
This polycysteic acid/CNTs composite film may be considered
to be a promising, low-cost, durable, and biocompatible material
for the modification of sensors in applications to pharmaceutical
and biomedical analysis.
[Back to top]
Polymeric Liquid Membrane Electrodes Incorporated
with Undecylcalix[4]-Resorcinarene for Screening of Neutral
Forms of Diaminobenzene Isomers
Katarzyna Kurzatkowska, Hanna Radecka, Wim Dehaen, Michal
Wasowicz, Izabela Grzybowska and Jerzy Radecki
The PVC supported liquid membrane electrodes incorporated
with undecylcalix[4]resorcinarene (UDC[4]Rene) generates a
cationic potentiometric response after stimulation by neutral
(unprotonated) form of diaminobenzene isomers. The potentiometric
signals were generated upon the formation of supramolecular
complex between the UDC[4]Rene (host) and diaminobenzene (guest)
at the organic-aqueous interface. In this paper for the first
time we report the generation of cationic potential signal
by electrode incorporated with host molecule possessing oxygen
as a heteroatom, after stimulation with neutral guest containing
nitrogen in its structure We also broaden the family of receptor
molecules, which are able to generate charge separation at
the organic/aqueous interface after interaction with uncharged
molecules. The results obtained confirm the possibility of
applying this potentiometric method for the screening of diaminobenzene
isomers identified recently as allergens and endocrine disrupting
chemicals.
[Back to top]
Analysis of Metformin Dosage Formulations by Capillary
Electrophoresis at Nano Scale Detection
Imran Ali, Hassan Y. Aboul-Enein and Vinod K. Gupta
An inexpensive, rapid and reproducible capillary electrophoretic
method has been developed and validated for the determination
of metformin in pharmaceutical preparations. The method was
developed utilizing a fused silica capillary (60 cm x 50 μm
I.D.), phosphate buffer (50 mM, 3.0 pH)-acetonitrile (95:5,
v/v) as background electrolyte (BGE), 20 kV applied voltage
with UV detection at 254 nm and at a working temperature of
23±1ºC. Linearity was observed in the concentration
range from 100 ng/L to 5 µg/L, with a correlation coefficient
(R2) of 0.9998. The limits of detection and quantification
achieved were 60 and 100 ng/mL, respectively. The recovery
of metformin from pharmaceutical preparations was 99.1%. These
validation parameters demonstrate the precision of the method
and its suitability for the determination of metformin in
pharmaceutical tablet formulations.
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