Research activities – Daniel Mandler

Mandler's group deals with a wide range of scientific activities spanning from basic to applied research. The common base of these activities is either electrochemistry, surface science or coatings. During the last years, we have specifically focused on the following research activities:

  1. Electrochemistry with high resolution – this topic started with scanning electrochemical microscopy (SECM) where Mandler was one of the pioneers using this technique for patterning surfaces. We have used SECM for carrying out a wide range of surface modifications, such as metal deposition and etching, and studying electron transfer processes, e.g., in conducting polymer and electrochromic materials. Specifically, we have recently focused on the local deposition of nanomaterials such as metallic and other nanoparticles. We have shown that SECM can be used for local deposition and shape control of nanostructures. In principle, the general concept was to use electrochemical probes to locally deposition nanostructures under conditions, which will result in anisotropic growth. We suggested a few approaches that are schematically depicted in the figure below. We have shown that it is possible to control the local formation of different anisotropic nanoparticles by introducing either self-assembled monolayers, surfactants to the solution or an enzyme that catalyzed the reduction of the metal ions. At present, we are trying to combine electrochemistry and printing. This is very ambitious and we currently use other scanning probe microscopy methods.

    Figure 1-Approaches for the anisotropic local deposition of nanoparticles
  2. Coating of medical implants – we have been involved for many years in functional coatings and in particular coating of medical implants such as stents and orthopedic implants. Recently, we have collaborated with Prof. Noam Eliaz from the Tel Aviv University and focused on the electrochemical coating of titanium based orthopedic implants by hydroxyapatite (HAp). We have succeeded to develop new approached for the electrochemical deposition of hydroxyapatite nanoparticles by applying moderate potentials to negatively charged HAp nanoparticles. The essence is depicted below. In addition, we have been able to incorporate different antibiotics into nanoparticles to accommodate, for the first time, drugs or in the course of electrochemical deposition.

    Figure 2-Nano to nano-electrochemical deposition of hydroxyapatite nanoparticles
  3. From "nano to nano" a new approach in electrochemical deposition – We have recently demonstrated that electrochemistry can be used as a means of driving the deposition of nanomaterials. The concept was termed by us: "from nano to nano" which means to begin with well-defined nanomaterials dispersed in the electrolyte, and to end with thin coatings and patterns, which maintain the nanometric particulate nature of the dispersion. We have developed two approaches; the first is based on changing the pH on the electrode surface, while the second comprises the electrochemical induced increasing the ionic strength. In both mechanisms, the electrical potential causes eventually the decrease of inter-particle repulsions. The figure below shows one of our recent successes in which a wide range of 1-3D nanomaterials, i.e., VO2 and Au nanoparticles, carbon nanotubes and graphene oxide, were successfully deposited.

    Figure 3-Electrochemical induced deposition of nanomaterials by increasing the ionic strength
  4. Nanoparticles imprinted matrices (NAIM) – Despite the increased awareness of NPs' risks, currently there are no technologies for on-site detection and analysis of NPs.  At present, detection and analysis of NPs generally requires sophisticated instrumentations, such as scanning and transmission electron microscopy, dynamic light scattering, etc., which do not enable on-site and low cost applications. Furthermore, as the toxicity of NPs depends in large part upon on their size, shapes, and stabilizing shells, comprehensive characterization of NPs, i.e. "nanoparticle speciation", will likely emerge as a highly important issue in analytical chemistry.
    We have recently developed a novel approach that is based on the concept of "molecular imprinting polymers" in which the nanoparticles are imprinted in a matrix followed by their removal to form printed shapes (voids) of the nanoparticles. The latter were found to selectively reuptake the original size and shape nanoparticles. 
    Figure 4-Nanoparticles Imprinted Matrices
  5. Electroanalytical chemistry - …
  6. Solar thermal energy - .....
  7. Forensic science – ....