Publications

2016
Shahar T, Tal N, Mandler D. Molecularly imprinted polymer particles: Formation, characterization and application. Colloids Surf., AColloids and Surfaces, A: Physicochemical and Engineering Aspects. 2016;495 :11 - 19.Abstract
Molecularly imprinted polymer (MIP) particles offer many advantages as recognition objects. Therefore, we examd. thoroughly the effect of various exptl. parameters including cross-linker concn., nature of solvent, type of template and its concn., reaction vol. and temp. on the formation of particulate MIPs using pptn. polymn. The particles were characterized by various methods, such as XHR-SEM, HR-TEM and BET. Statistical calcns. were carried out using ImageJ software over population of at least 200 particles in each expt. The reproducibility of MIP synthesis was examd. and the SD was better than 10%. MIP particles were imprinted with different Sudan dye derivs. (Sudan II, III, IV and Sudan orange G). Raman and FTIR spectroscopies were used to prove the successful imprinting. Reuptake measurements were carefully compared between non-imprinted molecularly polymer (NIP) and MIP particles employing the same quantity and similar diam. and polydispersity of NIP and MIP, as never reported before. The results showed that MIP particles imprinted by Sudan IV showed higher selectivity toward this specific dye as compared with MIPs imprinted by other Sudan dyes and NIPs. [on SciFinder(R)]
Turyan I, Khatwani N, Sosic Z, Jayawickreme S, Mandler D. A novel approach for oxidation analysis of therapeutic proteins. Anal. Biochem.Analytical Biochemistry. 2016;494 :108 - 113.Abstract
Measuring and monitoring of protein oxidn. modifications is important for biopharmaceutical process development and stability assessment during long-term storage. Currently available methods for biomols. oxidn. anal. use time-consuming peptide mapping anal. Therefore, it is desirable to develop high-throughput methods for advanced process control of protein oxidn. Here, we present a novel approach by which oxidative protein modifications are monitored by an indirect potentiometric method. The method is based on adding an electron mediator, which enhances electron transfer (ET) between all redox species and the electrode surface. Specifically, the procedure involves measuring the sharp change in the open circuit potential (OCP) for the mediator system (redox couple) as a result of its interaction with the oxidized protein species in the soln. Application of Pt and Ag/AgCl microelectrodes allowed for a high-sensitivity protein oxidn. anal. We found that the Ru(NH3)2+/3+6 redox couple is suitable for measuring the total oxidn. of a wide range of therapeutic proteins between 1.1 and 13.6%. Accuracy detd. by comparing with the known percentage oxidn. of the ref. std. showed that percentage oxidn. detd. for each sample was within ±20% of the expected percentage oxidn. detd. by mass spectrometry. [on SciFinder(R)]
Hitrik M, Pisman Y, Wittstock G, Mandler D. Speciation of nanoscale objects by nanoparticle imprinted matrices. NanoscaleNanoscale. 2016 :Ahead of Print.Abstract
The toxicity of nanoparticles is not only a function of the constituting material but depends largely on their size, shape and stabilizing shell. Hence, the speciation of nanoscale objects, namely, their detection and sepn. based on the different species, similarly to heavy metals, is of outmost importance. Here we demonstrate the speciation of gold nanoparticles (AuNPs) and their electrochem. detection using the concept of "nanoparticles imprinted matrixes" (NAIM). Neg. charged AuNPs are adsorbed as templates on a conducting surface previously modified with polyethylenimine (PEI). The selective matrix is formed by the adsorption of either oleic acid (OA) or poly(acrylic acid) (PAA) on the non-occupied areas. The AuNPs are removed by electrooxidn. to form complementary voids. These voids are able to recognize the AuNPs selectively based on their size. Furthermore, the selectivity could be improved by adsorbing an addnl. layer of 1-hexadecylamine, which deepened the voids. Interestingly, silver nanoparticles (AgNPs) were also recognized if their size matched those of the template AuNPs. The steps in assembling the NAIMs and the reuptake of the nanoparticles were characterized carefully. The prospects for the anal. use of NAIMs, which are simple, of small dimension, cost-efficient and portable, are in the sensing and sepn. of nanoobjects. [on SciFinder(R)]
He L, Wang Q, Mandler D, Li M, Boukherroub R, Szunerits S. Detection of folic acid protein in human serum using reduced graphene oxide electrodes modified by folic-acid. Biosensors & Bioelectronics. 2016;75 :389 - 395.Abstract

The detection of disease markers is considered an important step for early diagnosis of cancer. We design in this work a novel electrochem. sensing platform for the sensitive and selective detection of folic acid protein (FP). The platform is fabricated by electrophoretic deposition (EPD) of reduced graphene oxide (rGO) onto a gold electrode and post-functionalization of rGO with folic acid. Upon FP binding, a significant current decrease can be measured using differential pulse voltammetry (DPV). Using this scheme, a detection limit of 1 pM is achieved. Importantly, the method also allows the detection of FP in serum being thus an appealing approach for the sensitive detection of biomarkers in clin. samples. [on SciFinder(R)]

2015
Liu L, Yellinek S, Tal N, Toledano R, Donval A, Yadlovker D, Mandler D. Electrochemical co-deposition of sol-gel/carbon nanotube composite thin films for antireflection and non-linear optics. JOURNAL OF MATERIALS CHEMISTRY C. 2015;3 (5) :1099-1105.
Ratner N, Mandler D. Electrochemical Detection of Low Concentrations of Mercury in Water Using Gold Nanoparticles. ANALYTICAL CHEMISTRY. 2015;87 (10) :5148-5155.
Peled Y, Krent E, Tal N, Tobias H, Mandler D. Electrochemical Determination of Low Levels of Uranyl by a Vibrating Gold Microelectrode. ANALYTICAL CHEMISTRY. 2015;87 (1, SI) :768-776.
Teodorescu F, Rolland L, Ramarao V, Abderrahmani A, Mandler D, Boukherroub R, Szunerits S. Electrochemically triggered release of human insulin from an insulin-impregnated reduced graphene oxide modified electrode. CHEMICAL COMMUNICATIONS. 2015;51 (75) :14167-14170.
Ratner N, Mandler D. Electrochemical Detection of Low Concentrations of Mercury in Water Using Gold Nanoparticles (vol 87, pg 5148, 2015). ANALYTICAL CHEMISTRY. 2015;87 (14) :7492.
Bera RK, Azoubel S, Mhaisalkar SG, Magdassi S, Mandler D. Fabrication of Carbon Nanotube/Indium Tin Oxide ``Inverse Tandem'' Absorbing Coatings with Tunable Spectral Selectivity for Solar-Thermal Applications. ENERGY TECHNOLOGY. 2015;3 (10) :1045-1050.
Liu L, Yellinek S, Valdinger I, Donval A, Mandler D. Important Implications of the Electrochemical Reduction of ITO. ELECTROCHIMICA ACTA. 2015;176 :1374-1381.
Ling H, Liu L, Lee PS, Mandler D, Lu X. Layer-by-Layer Assembly of PEDOT:PSS and WO3 Nanoparticles: Enhanced Electrochromic Coloration Efficiency and Mechanism Studies by Scanning Electrochemical Microscopy. ELECTROCHIMICA ACTA. 2015;174 :57-65.
Gdor E, Shemesh S, Magdassi S, Mandler D. Multienzyme Inkjet Printed 2D Arrays. ACS APPLIED MATERIALS & INTERFACES. 2015;7 (32) :17985-17992.
Bruchiel-Spanier N, Mandler D. Nanoparticle-Imprinted Polymers: Shell-Selective Recognition of Au Nanoparticles by Imprinting Using the Langmuir-Blodgett Method. CHEMELECTROCHEM. 2015;2 (6) :795-802.
Fam DWH, Azoubel S, Liu L, Huang J, Mandler D, Magdassi S, Tok AIY. Novel felt pseudocapacitor based on carbon nanotube/metal oxides. JOURNAL OF MATERIALS SCIENCE. 2015;50 (20) :6578-6585.
Ratner N, Mandler D. Electrochemical detection of low concentrations of mercury in water using gold nanoparticles. Anal ChemAnalytical chemistry. 2015;87 (10) :5148 - 55.Abstract
The electrochemical detection of mercury in aqueous solutions was studied at glassy carbon (GC) and indium-tin oxide (ITO) electrodes modified by gold nanoparticles (Au NPs). Two methods of modification were used: electrochemical reduction of HAuCl4 and electrostatic adsorption of Au NPs stabilized by citrate. We found that the Au NPs modified surfaces yielded higher sensitivity and sharper and more reproducible stripping peaks of Hg as compared with the bare electrodes. The effect of the modification by Au NPs on the stripping potential was examined. Interestingly, the stripping of Hg on GC and ITO modified by Au NPs occurred at the same potential as on bare GC and ITO, respectively. Only the full coverage of ITO by either electrochemically deposited Au for a long time or by vapor deposition, shifted the stripping potential more positive by ca. 0.4 V to that observed on a bare Au electrode. These and further experiments led us to conclude that the Au NPs served as nucleation sites for the deposition of Hg, whereas the GC or ITO are superior for the stripping of mercury. Hence, a combination of well-defined Au NPs on ITO or GC were found ideal for the electrochemical detection of Hg. Indeed, we achieved a remarkable detection limit of 1 μm·L(-1) of Hg using an ITO surface modified by electrostatically adsorbed Au NPs.[on SciFinder (R)]
Peled Y, Krent E, Tal N, Tobias H, Mandler D. Electrochemical determination of low levels of uranyl by a vibrating gold microelectrode. Anal ChemAnalytical chemistry. 2015;87 (1) :768 - 76.Abstract
In this work we report the sensitive electroanalytical detection of uranium(VI) in aqueous solutions. Uranium commonly exists in aqueous solutions in the form of its oxo ion, uranyl (U(VI)O2(2+)). The detection of uranyl has been accomplished by us through its deposition upon reduction by two electrons to the insoluble UO2 using a bare disk gold macroelectrode and anodic stripping voltammetry (ASV). This gave an unsatisfactory detection limit of ca. 1 × 10(-5) M uranyl. Moreover, the evolution of hydrogen bubbles blocked the electrode surface as a result of water reduction at negative deposition potential (-0.7 V vs Ag/AgCl). The application of a 25 μm diameter Au microwire electrode on which UO2 precipitated at negative potential (-1.2 V) improved substantially the detection limit. Further improvement was accomplished by vibrating the microwire working electrode, which increased the amounts of UO2 deposition due to decreasing the diffusion layer. The effect of the vibrating amplitude and frequency on the electroanalytical response was studied and optimized. Eventually, a detection limit of ca. 1 × 10(-9) M uranyl was achieved using a 5 min deposition time, -1.2 V deposition potential, and vibrating the electrode at frequency of 250 Hz and amplitude of 6 V.[on SciFinder (R)]
Ratner N, Mandler D. Correction to Electrochemical Detection of Low Concentrations of Mercury in Water Using Gold Nanoparticles. Anal ChemAnalytical chemistry. 2015;87 (14) :7492.
Teodorescu F, Rolland L, Ramarao V, Abderrahmani A, Mandler D, Boukherroub R, Szunerits S. Electrochemically triggered release of human insulin from an insulin-impregnated reduced graphene oxide modified electrode. Chem Commun (Camb)Chemical communications (Cambridge, England). 2015;51 (75) :14167 - 70.Abstract
An electrochemical insulin-delivery system based on reduced graphene oxide impregnated with insulin is described. Upon application of a potential pulse of -0.8 V for 30 min, up to 70 ± 4% of human insulin was released into a physiological medium while preserving its biological activity.[on SciFinder (R)]
Gdor E, Shemesh S, Magdassi S, Mandler D. Multienzyme Inkjet Printed 2D Arrays. ACS Appl Mater InterfacesACS applied materials & interfaces. 2015;7 (32) :17985 - 92.Abstract
The use of printing to produce 2D arrays is well established, and should be relatively facile to adapt for the purpose of printing biomaterials; however, very few studies have been published using enzyme solutions as inks. Among the printing technologies, inkjet printing is highly suitable for printing biomaterials and specifically enzymes, as it offers many advantages. Formulation of the inkjet inks is relatively simple and can be adjusted to a variety of biomaterials, while providing nonharmful environment to the enzymes. Here we demonstrate the applicability of inkjet printing for patterning multiple enzymes in a predefined array in a very straightforward, noncontact method. Specifically, various arrays of the enzymes glucose oxidase (GOx), invertase (INV) and horseradish peroxidase (HP) were printed on aminated glass surfaces, followed by immobilization using glutardialdehyde after printing. Scanning electrochemical microscopy (SECM) was used for imaging the printed patterns and to ascertain the enzyme activity. The successful formation of 2D arrays consisting of enzymes was explored as a means of developing the first surface confined enzyme based logic gates. Principally, XOR and AND gates, each consisting of two enzymes as the Boolean operators, were assembled, and their operation was studied by SECM.[on SciFinder (R)]

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