Electro-Assisted Deposition of Calcium Phosphate on Self-Assembled Monolayers

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Authors: Noah Metoki1, Kazi Sadman2, Kenneth Shull2, Noam Eliaz1 and Daniel Mandler3

1Biomaterials and Corrosion Lab, Department of Materials Science and Engineering, Tel-Aviv University, Ramat Aviv 6997801, Israel
2Polymer Surfaces & Inferfaces Lab, Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
3Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel

Journal: Electrochimica Acta (2016)

Abstract: Calcium phosphate (CaP) ceramics are used in orthopedics and dentistry due to their excellent biocompatibility and osseointegration. Here, the electro-assisted deposition of CaP on two different selfassembled monolayers (SAMs), 2-mercaptoacetic acid (MAA) and 2-mercaptoethanol (ME), was studied both at short (up to 3 min) and long (2 hours) deposition periods on well-defined evaporated gold surfaces. It was found that the end group of the monolayer has a major effect on the growth of the CaP coating. The deposition was slower and less electrically efficient on MAA SAM, but surface cracking was essentially eliminated due to reduction of the crystallographic mismatch. The carboxylic acid may
facilitate CaP growth by attracting Ca2+ ions to the surface, which could explain the higher amount of side reactions occurring at the beginning of the deposition.

Keywords: Calcium phosphate (CaP), hydroxyapatite (HAp), electrodeposition, self- assembled monolayers (SAMs)

Design and Validation of a 150 MHz HFFQCM Sensor for Bio-Sensing Applications

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Authors: Román Fernández1, Pablo García1, María García1, José V. García1, Yolanda Jiménez2 and Antonio Arnau2

1Advanced Wave Sensors S. L., Algepser 24, 46988 Paterna, Spain
2Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Camí de Vera S/N, 46022 Valencia, Spain

Journal: Sensors Journal (2017)

Abstract: Acoustic wave resonators have become suitable devices for a broad range of sensing applications due to their sensitivity, low cost, and integration capability, which are all factors that meet the requirements for the resonators to be used as sensing elements for portable point of care (PoC) platforms. In this work, the design, characterization, and validation of a 150 MHz high fundamental frequency quartz crystal microbalance (HFF-QCM) sensor for bio-sensing applications are introduced. Finite element method (FEM) simulations of the proposed design are in good agreement with the electrical characterization of the manufactured resonators. The sensor is also validated for bio-sensing applications. For this purpose, a specific sensor cell was designed and manufactured that addresses the critical requirements associated with this type of sensor and application. Due to the small sensing area and the sensor’s fragility, these requirements include a low-volume flow chamber in the nanoliter range, and a system approach that provides the appropriate pressure control for assuring liquid confinement while maintaining the integrity of the sensor with a good base line stability and easy sensor replacement. The sensor characteristics make it suitable for consideration as the elemental part of a sensor matrix in a multichannel platform for point of care applications.

Keywords: HFF-QCM (high fundamental frequency quartz crystal microbalance); finite element method (FEM); flow cell; biosensor; PoC (point of care); MQCM (monolithic quartz crystal microbalance)

 Sensors 17 02057 g002 550

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A liquid biopsy platform combining a high fundamental frequency QCM device with dynamic chemistry for detecting mutations in circulating DNA

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Authors: A. Grammoustianou, G. Papadakis, M. Tabraue, J.J. Díaz-Mochon, R. Fernández, J.V. García, A. Arnau, E. Gizeli. AWSensors S.L., Institute of Molecular Biology and Biotechnology- FORTH, University of Crete, Destina Genomics S.L., Centro de Investigación e Innovación en Bioingeniería – Universidad Politécnica de Valencia

Event:  5th International Conference on Bio-sensing Technology, Riva del Garda, Italy (2017)

In the past decade, the analysis of circulating tumour DNA (ctDNA) in blood has been a major breakthrough; ctDNA has been proposed as a priceless source for cancer diagnostic, prognostic and treatment monitoring through a new methodology known as “Liquid Biopsy”. This study presents a novel diagnostic method for the acoustic detection of KRAS mutations in ctDNAs based on: (1) DNA analysis by “dynamic chemistry” that utilizes aldehyde modified nucleobases (SMART) and abasic peptide nucleic acids (DGL probes) capable for the errorfree detection of nucleic acids and their mutations; and, (2) a high fundamental frequency (100 MHz) acoustic wave microsensor (AWS HFF-QCM) that allows the accurate, inexpensive, label-free and real time monitoring of the “dynamic chemistry”. Surface-immobilized DGL probes on the AWS HFF-QCM device are used to detect ctDNAs of wild type and mutated KRAS variants. Upon hybridization of the DGL probe with its target ssDNA, a duplex is formed where biotin- tagged SMART bases can lock in front of the position under interrogation; streptavidin binding detected in a follow-up step confirms the presence of the SMART bases. The use of DGL probes in combination with an isothermal DNA amplification step RPA) have allowed the sensitive and specific recognition of single mismatches in KRAS genes in less than 1 hour. This work presents a unique and novel technology that can emerge as a promising tool in the field of cancer diagnostics.

Liquid Biopsy detection protocol

Schema for complete detection protocol:

(A) Extracted DNA containing mutant (red) and wild type DNA fragments (black) are enzymatically amplified.

(B) Denatured amplicons are hybridized on surface immobilized DGL probes. Chemical locking of a specific tagged SMART base takes place only in the appropriate position.

(C) Incorporated SMART bases are recognized by streptavidin and monitored in real-time during an acoustic measurement.

A High Fundamental Frequency QCM Immunosensor for Tuberculosis Detection

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AWSensors biosensor for tuberculosis detection

Authors: Ángel Montoya, Carmen March, Yeison J. Montagut, Maria J. Moreno, Juan J. Manclus, Antonio Arnau, Yolanda Jiménez, Marisol Jaramillo, Paula A. Marin, Robinson A. Torres

Journal:  Current topics in Medicinal Chemistry (2017)

Background: Tuberculosis, one of the oldest diseases affecting human beings, is still considered as a world public health problem by the World Health Organization.

Method & Material: Therefore, there is a need for new and more powerful analytical methods for early illness diagnosis. With this idea in mind, the development of a High Fundamental Frequency (HFF) piezoelectric immunosensor for the sensitive detection of tuberculosis was undertaken. A 38 kDa protein secreted by Mycobacterium tuberculosis was first selected as the target biomarker. Then, specific monoclonal antibodies (MAbs) were obtained. Myc-31 MAb, which showed the highest affinity to the analyte, was employed to set up a reference enzyme-linked immunosorbent assay (ELISA) with a limit of detection of 14 ng mL-1 of 38 kDa antigen.

Results & Discussion: For the development of the HFF piezoelectric immunosensor, 100 MHz AWSensors quartz crystals were used as transducer elements. The gold electrode surface was functionalized by covalent immobilization of the target biomarker through mixed self-assembled monolayers (mSAM) of carboxylic alkane thiols. A competitive immunoassay based on Myc-31 MAb was integrated with the transducer as sensing bio-recognition event. Reliable assay signals were obtained using low concentrations of antigen for functionalization and MAb for the competitive immunoassay. Under optimized conditions, the HFF immunosensor calibration curve for 38 kDa determination showed a limit of detection as low as 11 ng mL-1 of the biomarker. The high detectability attained by this immunosensor, in the picomolar range, makes it a promising tool for the easy, direct and sensitive detection of the tuberculosis biomarker in biological fluids such as sputum.

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Dynamic Resolution of Ion Transfer in Electrochemically Reduced Graphene Oxides Revealed by Electrogravimetric Impedance

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Authors: Hamza Goubaa, Freddy Escobar-Teran, Ibtissam Ressam, Wanli Gao, Abdelkrim el Kadib, Ivan T. Lucas, Mustapha Raihane, Mohammed Lahcini, Hubert Perrot, Ozlem Sel. Sorbonne Université, UPMC, Univ Paris 06, CNRS, France. Laboratoire Interfaces et Systèmes Électroquimiques; Université Cadi Ayyad, Faculté des Sciences et Techniques, Laboratoire de Chimie Organométallique et Macromoléculaire Matériaux composites, Marrakech, Morocco.

Journal:  The Journal of Physical Chemistry (2017)

To accompany the search for optimal materials in electrochemical supercapacitors, appropriate characterization tools to assess key parameters of newly developed electrodes are required. Here we demonstrate the capabilities of ac-mode electrogravimetry to study in details the capacitive charge storage mechanisms in electrochemically reduced graphene oxide (ERGO) thin films electrodes. The coupling of electrochemical impedance spectroscopy (EIS) with fast quartz crystal microbalance (QCM) complements classical electrochemical quartz crystal microbalance (EQCM) by capturing here the dynamics of the electroadsorption process, identifying charged moieties and detecting solvation effects. We evidenced the co-electroadsorption of two types of cationic species (fully and partially hydrated cations) in the potential range studied and the indirect intervention of free solvent molecules. Further kinetic information on electroadsorption is also obtained which leads to a full deconvolution of the global EQCM response at both gravimetric and temporal level. Through a fine analysis of the interactions of different cations of period one elements, Li+, Na+ and K+ with ERGO, we evidenced the critical role of solvation processes on the kinetics of electroadsorption, and provided an experimental proof to the phenomena that smaller ions are more tightly bound to their water molecules such that an inverse relationship exists between the dehydration energy and the ion size. Such gravimetric and dynamic subleties are unreachable with classical tools and with EQCM method alone which permits us to suggest the ac-mode electrogravimetry as a baseline diagnostic tool to explore charge transfer mechanisms at the nanoscale.

Electrochemical and viscoelastic evolution of dodecyl sulfate-doped polypyrrole films during electrochemical cycling

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Authors: Wanli Gao, Ozlem Sel, Hubert Perrot

Journal:  Electrochimica Acta (2017)

The correlation between electrochemical and viscoelastic properties of electrodeposited dodecysulfatedoped polypyrrole (PPy-DS) during electrochemical cycling process was described through combining electrochemical quartz-crystal microbalance (EQCM), ac-electrogravimetric characterizations and electroacoustic measurements. as the PPy-DS electrode evolves during the course of consecutive cycling in aqueous NaCI electrolyte, the film exhibits (i) an obvious ion-selective transition from cations to anions in the charge compensation process; (ii) an inferior electrochemical performance accompanied with increased stiffness (increased storaged moduli, G’); and (iii) depleted capability of ionic exchange through film/electrolyte interface. PPy-DS conducting polymer electrodes (CPEs) are of interest in energy storage and the relationship between electrochemical and viscoelastic properties during electrochemical cycling process is essential for promoting the performance of these devices. In this perspective, ac-electrogravimetry combined with electroacoustic measurements can be suggested as an alternative method to synchronously probe the electrochemical and mechanical evolution and has the potential to offer a generalized route to study aging mechanism of CPEs.

 

pH Controlled Electrochemical Deposition of Polyelectrolyte Complex Films

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Authors: Kazi Sadman, Qifeng Wang, Shawn H Chen, David Efim Delgado and Kenneth R Shull. Northwestern University, Evanston, Illinois, US

Journal:  Langmuir 2017, 33(8) 1834-1844.

Abstract: Polyelectrolyte complex (PEC) films made from oppositely charged polymer chains have applications as drug delivery vehicles, separation membranes, and biocompatible coatings. Conventional layer-by-layer (LbL) techniques for polyelectrolyte coatings are low-throughput and multistep processes that are quite slow for building films on the order of micrometers. In this work, PEC films are electrochemically deposited using a rapid one-pot method yielding thick (1 μm) films within short experimental time scales (5 min). This rapid electrodeposition is achieved by exploiting the reduction of hydrogen peroxide at mild electrode potentials that avoid water electrolysis, yet trigger the pH responsive self-assembly of a PEC film composed of poly(acrylic) acid and poly (allylamine) HCl. In-situ rheology using an electrochemical quartz crystal microbalance (EQCM) quantified the shear modulus-density product of the deposited layer to be on the order of 107 Pa-g/cm3 at a frequency of 15 MHz, with a viscoelastic phase angle at this frequency of approximately 50○. This electrodeposition scheme furthers the development of PEC coatings for more high-throughput applications where a fast and efficient single step approach would be desirable for obtaining coatings.

Link: https://doi.org/10.1021/acs.langmuir.6b04491

Gravimetric and dynamic deconvolution of global EQCM response of carbon nanotube based electrodes by Ac-electrogravimetry

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Authors: F. Escobar-Teran, A. Arnau, J.V. García, Y. Jiménez, H. Perrot, O. Sel

Journal: Electrochemistry communications (2016)

The capacity charge storage of carbon nanotube (CNT) based electrodes was investigated by ac-electrogravimetry which couples fast quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS). In contact with an aqueous NaCI electrolyte, evidence was found that there are two types of cations (Na+.H2O and H+) electroadsorbed with different kinetics for cathodic potentials and the Cl– ionsfor anodic potentials together with free water molecules. The reconstruction of the total mass response from independent ac-electrogravimetry measurements agrees perfectly well with the global EQCM response. Our findings reveal the unique sensitivity of the ac-electrogravimetry to provide a fair gravimetric and dynamic deconvolution of the global EQCM responses.

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Calcium-induced calmodulin conformational change. Electrochemical evaluation

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Authors: Isabel P.G. Fernandes, Ana Maria Oliveira-Brett. Chemistry Department, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal.

Journal: Bioelectrochemistry (2016)

Calmodulin (CaM) is an essential protein present in all eukaryote cells, ranging from vertebrates to unicellular organisms. CaM is the most important Ca2+ signalling protein, composed of two domains,  N- and C-terminal domains, linked by a flexible central α – helix, and is responsible for the regulation of numerous calcium-mediated signalling pathways. Four calcium ions bind to CaM, changing its conformation and determining how it recognizes and regulates its cellular targets. The oxidation mechanism of native and denatured CaM, at a glassy carbon electrode, was investigated using differential pulse voltammetry and electrochemical impedance spectroscopy. Native and denatured CaM presented only one oxidation peak, related to the tyrosine amino acid residue oxidation. Calcium-induced calmodulin conformational change and the influence of Ca2+ concentration on the electrochemical behaviour of CaM were evaluated, and significant differences, in the tyrosine amino acid residue peak potential and current, in the absence and in the presence of calcium ions, were observed. Gravimetric measurements were performed with a graphite coated piezoelectric quartz crystal with adsorbed CaM and calcium aggregation by CaM was demonstrated.

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HFF-QCM immunosensor for fast and sensitive detection of DDT in honey

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Summary

The control of chemical residues is essential in honey’s marketing to ensure consumer safety. Equipments available in the market reach the required limit of detection (LOD) (e.g. Liquid Cromatography- HPLC) but are not suitable for in-situ implantation in honey packaging industry. The reasons are:

  • High qualified staff required
  • High cost
  • Time-consuming

Other approaches available in the market, although faster and without the need of qualified staff, do not reach the required LODs. Piezoelectric immunosensors based on High Fundamental Frequency Quartz Crystal Microbalance (HFF-QCM) combined with an antigen-antibody recognition process, are alternative or complementary technologies suitable for chemical residues control in food.

The analytical performance of AWS-A20 and AWS-F20 platforms (based on HFF-QCM technology) has been tested for the detection of pesticide residues (DDT) in honey.

AWS platforms lead to the following benefits:

  • Lower cost
  • Less sample/reagent consumption
  • Label-free, direct and real time transduction

DDT standard curves performed in laboratory buffer provided:

  • Sensitivity (estimated as the I50 value): 0.62 µg/L
  • LOD in the 0.05 – 0.1 µg/L range

Remarks

  • A HFF-QCM immunosensors for DDT insecticide has been developed
  • Efficient biosensing interfaces were achieved by covalent functionalization of the sensor gold electrodes with mixed alkane-thiol self-assembled monolayers (mSAMs)
  • High-sensitivity monoclonal antibodies were used as the bio-recognition element of the target analyte in a competitive immunoassay format.
  • The limits of detection (LOD) and quantification (LOQ) and the working range (WR) of the developed HFF-QCM immunosensor for DDT are in the same order of magnitude as those previously reported for ELISA and SPR immunosensor.

 

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