Towards a new biosensor concept using single-impact electrochemistry: Effect of material characteristics on silver nanoparticle adsorption

Introduction

Figure 1: (a) Detection of an individual AgNP using impact electrochemistry [1]. (b) AgNP sensor with a 3D-printed microfluidic system on top.

Silver nanoparticles (AgNPs) offer promising characteristics as a novel carrier system in biosensor applications. Here, we use single impact electrochemistry based on the oxidation of individual AgNPs at an appropriately biased electrode to estimate the underlying AgNP concentration in solution [2, 3]. Via surface functionalization of the AgNPs, in principle this approach can be applied to indirectly measure the concentration of a specific target protein. However, AgNPs are prone to adhere to many surfaces used in additive manufacturing. This leads to an underestimation of the sample’s concentration or can—in the worst case—render the detection of low-concentration samples impossible. In this project, we want to investigate the adsorption of AgNPs as a function of certain surface characteristics.

Aim

In order to quantify the adhesion of AgNPs to different test surfaces, you will prepare samples of these materials, bring them in contact with suspensions of AgNPs, and measure the AgNPs’ concentration as a function of time and surface chemistry. To this end, you will…

  1. …test materials that are commonly used in additive manufacturing techniques such as ink-jet printing and stereolithography (3D printing),…
  2. …establish a measurement protocol to easily quantify AgNP concentrations based on dynamic light scattering,…
  3. …deduce common surface characteristics and material properties that are favourable or disadvantageous in the context of AgNP detection, and…
  4. …modify and/or fabricate resins and inks to achieve certain desired material properties

You will be introduced in an interdisciplinary working environment and will learn the following techniques:

  1. surface analysis techniques (e.g. profilometry and contact angle measurements to determine polar and disperse contributions to surface energy)
  2. dynamic light scattering (DLS) for quantitative AgNP detection
  3. additive manufacturing approaches (stereolithographic 3D printing, inkjet printing, drop casting)
  4. single-impact electrochemistry to verify the influence of material/AgNP interaction

Preferred knowledge

  1. strong background in chemistry or surface physics
  2. wet-lab experience and excellent analytical and experimental skills
  3. dedication and motivation to work on an interdisciplinary research topic self-reliantly

Possible starting date & further information

Potential starting date is as soon as possible. For further details and application contact Lennart Weiß in person or via email.

References

  1. S. V. Sokolov, S. Eloul, E. Kätelhön, C. Batchelor-McAuley and R. G. Compton, "Electrode–particle impacts: a users guide," Physical Chemistry Chemical Physics, vol. 19, no. 1, pp. 28-43, 2017.
  2. E. Tanner, C. Batchelor-McAuley and R. Compton, "Single nanoparticle detection in ionic liquids," The Journal of Physical Chemistry C, vol. 120, pp. 1959-1965, 2016.
  3. K. Krause, A. Yakushenko and B. Wolfrum, "Stochastic On-Chip Detection of Subpicomolar," Analytical Chemistry, vol. 87, pp. 7321-7325, 2015.