Electrodeposition of Gold on Fluorine-Doped Tin Oxide: Characterization and Application for Catalytic Oxidation of Nitrite

Rahman, Md. Mahbubur,Li, Xiao-Bo,Lopa, Nasrin Siraj,Lee, Jae-Joon Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.7

Sub-micrometer size gold particles were electrodeposited on a transparent fluorine-doped tin oxide (FTO) from acetonitrile solution containing $AuCl_4{^-}$ and tetramethylammonium tetraflouroborate (TMATFB) for detecting $NO_2{^-}$. A series of two-electron ($2e^-$) and one-electron ($1e^-$) reductions of the $AuCl_4{^-}-AuCl_2{^-}-Au$ redox systems were observed at FTO and a highly stable and homogeneous distribution of Au on FTO (Au/FTO) was obtained by stepping the potential from 0 to -0.55 V (vs. Ag/$Ag^+$). The Au/FTO electrode exhibited sufficiently high catalytic activity toward the oxidation of $NO_2{^-}$ with a detection limit (S/N = 3) and sensitivity of 2.95 ${\mu}M$ and 223.4 ${\mu}A{\cdot}cm^{-2}{\cdot}mM^{-1}$, respectively, under optimal conditions. It exhibited an interference-free signal for $NO_2{^-}$ detection with excellent recoveries from real samples.

A Conducting Poly(N-(1-Naphthyl)ethylenediamine dihydrochloride) Nanofibers for the Sensitive and Interference-Free Detection of Dopamine

Rahman, Md. Mahbubur,Ahmed, Arif,Lee, Jae-Joon The Electrochemical Society 2018 Journal of the Electrochemical Society Vol.165 No.3

<P>This research demonstrated the development of a stable, sensitive, and selective electrochemical method based on poly(N-(1-Naphthyl) ethylenediamine dihydrochloride) nanofibers-modified anodized glassy carbon electrode (PNEDA/AGCE) for the detection of dopamine (DA) in the presence of ascorbic acid (AA) and uric acid (UA). The PNEDA/AGCE sensor could easily separate the oxidation signals of AA, DA, and UA from their mixture solution in PBS (pH 7.0). It showed linear behavior over wide concentration ranges for DA sensing and the detection limits were ca. 0.070 and 0.075 mu M in PBS (pH 7.0) and diluted human serum samples respectively, while the sensitivities were ca. 0.085 and 0.080 mu A.mu M-1, respectively. The high sensitivity for the PNEDA/AGCE sensor can be ascribed to the facile H-bonding interaction between the free -NH2 groups of PNEDA and oxidizable -OH groups of DA, which was verified by Gradient-corrected density functional theory (DFT) calculation. The PNEDA/AGCE sensor showed excellent repeatability and reproducibility with very low RSD (%) and excellent recoveries of DA concentrations in human serum samples. (C) 2018 The Electrochemical Society.</P>

Highly sensitive and simultaneous detection of dopamine and uric acid at graphene nanoplatelet-modified fluorine-doped tin oxide electrode in the presence of ascorbic acid

Rahman, Md. Mahbubur,Lopa, Nasrin Siraj,Ju, Myung Jong,Lee, Jae-Joon Elsevier 2017 Journal of Electroanalytical Chemistry Vol.792 No.-

<P><B>Abstract</B></P> <P>We developed a graphene nanoplatelet-modified fluorine-doped tin oxide electrode (GNP/FTO) for the simultaneous detection of dopamine (DA) and uric acid (UA) in the presence of ascorbic acid (AA) and investigated the interaction mechanisms of DA, UA, and AA with GNPs considering their charging states at different pH values. Owing to the unique structure and properties originating from the oxygen and nitrogen functional groups at the edges, GNPs showed high electrocatalytic activity for the electrochemical oxidations of AA, DA, and UA with peak-to-peak potential separations (Δ<I>E</I> <SUB> <I>P</I> </SUB>) between AA-DA and DA-UA of <I>ca</I>. 0.23 and 0.17V, respectively. These values are sufficiently high to allow the simultaneous detection of DA and UA without interference from AA. The highly sensitive and stable GNP/FTO sensor showed sensitivities of <I>ca</I>. 0.15±0.004 and 0.14±0.007μA/μM, respectively, with detection limits of <I>ca</I>. 0.22±0.009 and 0.28±0.009μM, respectively, for DA and UA. The sensor could detect DA and UA concentrations in human serum samples with excellent recoveries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> FTO was modified with graphene nanoplatelets (GNPs) by the e-spray method. </LI> <LI> Dopamine and uric acid were simultaneously detected with GNP/FTO without interference from ascorbic acid. </LI> <LI> Sensor allows low detection limits of 0.22 and 0.28μM for dopamine and uric acid, respectively. </LI> <LI> Sensor shows good stability and recoveries from human serum samples. </LI> <LI> The interaction mechanisms between dopamine, uric acid, and ascorbic acid with GNPs were discussed and verified. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of the TiO₂ Nanotubes in the Photoelectrode on Efficiency of Dye-sensitized Solar Cell

Rahman, Md. Mahbubur,Son, Hyun-Seok,Lim, Sung-Su,Chung, Kyung-Ho,Lee, Jae-Joon The Korean Electrochemical Society 2011 Journal of electrochemical science and technology Vol.2 No.2

The effect of $TiO_2$ nanotube (TNT) and nanoparticle (TNP) composite photoelectrode and the role of TNT to enhance the photo conversion efficiency in dye-sensitized solar cell (DSSC) have investigated in this study. Results demonstrated that the increase of the TNT content (1-15 %) into the electron collecting TNP film increases the open-circuit potential ($V_{oc}$) and short circuit current density ($J_{sc}$). Based on the impedance analysis, the increased $V_{oc}$ was attributed to the suppressed recombination between electrode and electrolyte or dye. Photochemical analysis revealed that the increased Jsc with the increased TNT content was due to the scattering effect and the reduced electron diffusion path of TNT. The highest $J_{sc}$ (12.6 mA/$cm^2$), Voc (711 mV) and conversion efficiency (5.9%) were obtained in the composite photoelectrode with 15% TNT. However, $J_{sc}$ and $V_{oc}$ was decreased for the case of 20% TNT, which results from the significant reduction of adsorbed dye amount and the poor attachment of the film on the fluorine-doped tin oxide (FTO). Therefore, application of this composite photoelectrode is expected to be a promising approach to improve the energy conversion efficiency of DSSC.

An accidental fatal attack on domestic pigeons by honey bees in Bangladesh

RAHMAN, Md. Mahbubur,LEE, Sei-Jin,KIM, Gi-Beum,YANG, Dong Kwon,ALAM, Md. Rafiqul,KIM, Shang-Jin The Japanese Society of Veterinary Science 2015 The Journal of veterinary medical science Vol.77 No.11

<P>Fatalities among avian species due to multiple bee stings are rare. Sixteen pigeons on a farm in Bangladesh each suffered multiple bee stings. Ten of the pigeons died before treatment, 5 (4–11 stings) died within 12 hr after treatment, and 1 pigeon (only 3 stings) survived. Body temperature, heart rate, respiratory rate, hematocrit, hemoglobin, erythrocytes, thrombocytes, MCV, MCH and MCHC decreased significantly after the incident, but leucocytes, heterophils, basophils, eosinophils, monocytes, ALT, AST, LDH, CK, creatinine, BUN and UA increased markedly. Overall, the hematological and biochemical changes in the bee-stung pigeons were similar to those of mammals; however, avian species may be more sensitive to bee stings than mammals.</P>

Advances in electrochemical aptasensing for cardiac biomarkers

Rahman Md. Mahbubur,Lopa Nasrin Siraj,Lee Jae‐Joon 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.1

Novel bio-receptors or bio-recognition molecular markers with high specificity, stability, and affinity for the efficient binding and entrapment of target biomolecules are essential for developing biomedical devices with high sensitivity and reliability. Aptamers are peptide or nucleic-acid (DNA or RNA) molecules capable of binding to target biomarkers by forming a unique three-dimensional structure, providing an effective platform for biosensing. This review comprehensively summarizes the progress of label-free and label-based electrochemical aptasensors for the detection of various biomarkers related to cardiovascular diseases. It also outlines the fundamental properties of different cardiac biomarkers, synthesis of target-specific aptamers, and working principles, such as single receptor and sandwich, of the different types of sensing assays for the electrochemical detection of cardiac biomarkers while highlighting the current challenges and future perspectives.

Simultaneous Determination of Ranitidine and Metronidazole at Poly(thionine) Modified Anodized Glassy Carbon Electrode

Rahman, Md. Mahbubur,Li, Xiao-Bo,Jeon, Young-Deok,Lee, Ho-Joon,Lee, Soo Jae,Lee, Jae-Joon The Korean Electrochemical Society 2012 Journal of electrochemical science and technology Vol.3 No.2

A simple and sensitive electrochemical sensor for simultaneous and quantitative detection of ranitidine (RT) and metronidazole (MT) was developed, based on a poly(thionine)-modified anodized glassy carbon electrode (PTH/GCE). The modified electrode showed the excellent electrocatalytic activity towards the reduction of both RT and MT in 0.1M phosphate buffer solution (PBS, pH 7.0). The peak-to-peak separations (${\Delta}E_p$) for the simultaneous detection of RT and MT between the two reduction waves in CV and DPV were increased significantly from ca. 100 mV at anodized GCE, to ca. 550 mV at the PTH/GCE. The reduction peak currents of RT and MT were linear over the range from 35 to $500{\mu}M$ in the presence of 200 and $150{\mu}M$ of RT and MT, respectively. The sensor showed the sensitivity of 0.58 and $0.78{\mu}A/cm^2/{\mu}M$ with the detection limits (S/N = 3) of 1.5 and $0.96{\mu}M$, respectively for RT and MT.

Relationships between blood Mg2+ and energy metabolites/enzymes after acute exhaustive swimming exercise in rats.

Rahman, Md Mahbubur,Lee, Sei-Jin,Mun, A-Reum,Adam, Gareeballah Osman,Park, Ra-Mi,Kim, Gi-Beum,Kang, Hyung-Sub,Kim, Jin-Shang,Kim, Shang-Jin,Kim, Sung-Zoo Humana Press 2014 Biological trace element research Vol.161 No.1

<P>Magnesium (Mg) plays a central role in neuronal activity, cardiac excitability, neuromuscular transmission, muscular contraction, vasomotor tone, and blood pressure, all of which are significantly related to physical performance. To date, the available data about detection of blood total Mg (tMg; free-ionized, protein-bound, and anion-complex forms) are inconsistent, and there is limited information on blood free-ionized Mg (Mg(2+)) in relation to physical exercise. The aim of this study was to determine the biochemical changes related to energy metabolism after acute exhaustive swimming exercise (AESE) in rats in an attempt to correlate the role of blood Mg(2+) with metabolites/enzymes related to energy production. After AESE, blood Mg(2+), tMg, K(+), partial pressure of carbon dioxide, lactate, total protein (T-PRO), high-density lipoprotein (HDL), creatinine (CRE), blood urea nitrogen (BUN), uric acid (UA), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alanine phosphatase (ALP), lactate dehydrogenase (LDH), and creatinine kinase (CK) were significantly increased, whereas pH, partial pressure of oxygen, oxygen saturation, the Mg(2+)/tMg and Ca(2+)/Mg(2+) ratios, HCO3 (-), glucose, triglyceride (TG), and low-density lipoprotein (LDL) were significantly decreased. During AESE, lactate, T-PRO, albumin, AST, ALP, LDH, CK, CRE, BUN, and UA showed significant positive correlations with changes in blood Mg(2+), while glucose, TG, and LDL correlated to Mg(2+) in a negative manner. In conclusion, AESE induced increases in both blood Mg(2+) and tMg, accompanied by changes in blood metabolites and enzymes related to energy metabolism due to increased metabolic demands and mechanical damages.</P>

Provision of education to Rohingya refugee children in Bangladesh: exploring the forms of discrimination and intersectionality

Rahman ,Md Mahbubur,Shindaini ,Al Jamal Mustafa,Abdullah, A. B. M. 서울대학교 교육연구소 2023 Asia Pacific Education Review Vol.24 No.3

The article sheds light on discrimination that denies basic education to Rohingya refugee children currently living in the unregistered Kutupalong refugee camp at Cox’s Bazar, Bangladesh. The condition of basic education is partially due to the discrimination they experience in Rakhine State, Myanmar. It is further shaped by limited education opportunities they are ofered in the host country, Bangladesh. Employing a qualitative method, this study interviewed 18 informants from three categories: namely, Rohingya refugee children, guardians, and teachers (from Burmese and Bangladeshi backgrounds) and administered four focus group discussions to develop a deep understanding of their experiences. The results indicated that the unjust education opportunities provided by the Myanmar government and its divisive control of Rakhine State create various and linked forms of discrimination. The study revealed that ethnic identity, gender, religious background, age, and economic status play crucial roles in denying refugee children basic education in Myanmar and Bangladesh.

Ensuring Quality in Biometric Systems

Md. Mahbubur Rahman,Amit Karmaker,Md.Mahmudul Hasan,Samsuddin Ahmed 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.4

Biometric system is using for personal recognition of people in many social and economical activities now a days. A good biometric trait should be measurable, distinctive and stable over time. Real-world deployment of biometric systems often has to contend with degraded signal quality and erratic behavior of the biometric data. For last few years biometric data quality measure become an important concern after poor pathological sample and other many causes. The user, sensor and environmental facts are causes to quality degradation of biometric system. This study approaches that have been used to extract additional information about the biometric data that can then be used to improve performance in degraded conditions and also discuss about the sensor and environmental facts .This study will also discuss how this problem can be overcome to maintain the quality in biometric system with a special emphasis on face, fingerprint, iris modalities with different organizational standards.