Nanoparticles are used in many different areas including catalysis, drug delivery, sensing. Their applications critically depend on the interactions with small molecules. For instance, in nanoparticle catalysis, reagent molecules need to adsorb on the catalyst surface prior to the reaction. In drug delivery, the therapeutic cargo must bind to the nanoparticle until the release is triggered. In sensing, the interaction between the molecule and the nanoparticle results in a detectable signal.
Thanks to the developments in supramolecular chemistry, much is already known about non-covalent interactions in well-defined small molecule systems (e.g., host-guest interactions). In larger well-defined systems such as proteins or other biomacromolecules, intermolecular interactions have also been studied in detail. However, there is very little knowledge on the interactions in less well-defined materials such as nanoparticles, and the flexibility of these systems is likely to significantly affect their interactions. How strongly do small molecules bind to nanoparticles, and can we rationally tune this interaction by altering the properties of the organic shell on the nanoparticles? How fast is the binding, is it reversible, and how does this reversibility depend on the properties of the organic shell? These are the types of questions which are the focus of the current project.
Objectives and Novelty
The aim of this project is to observe and quantify the interactions between small molecules and functionalised nanoparticles. The project will start with developing a methodology for studying such interactions, and will then apply it to a range of well-characterised systems. Understanding these interactions will help us rationally design better drugs, sensors and catalysts.
The main method we will use to probe interactions with nanoparticles is EPR spectroscopy. We will label nanoparticles and/or small molecules with stable free radicals (nitroxides). EPR spectroscopy is ideally suited for studying interactions in complex nanosized systems, as only free radical labels contribute to the spectra. EPR is sensitive to a number of key parameters affected by intermolecular interactions, such as rate of tumbling, distance between adjacent labels, collisions between the labels. The changes of these parameters can be monitored in situ in fluid solutions making it possible to probe weak reversible interactions.
We will use several model nanoparticle systems complementary to the existing projects in our group. In the first instance, we will functionalise silica nanoparticles with an organic shell, and investigate binding of labelled guest molecules. The organic shell will be varied to change its thickness (e.g., using polymers with different chain length), and the properties of the functional groups in the shell (e.g., polarity, hydrogen-bonding ability etc). We are particularly interested in understanding the strength and rate of binding and selectivity. The project will then expand to look at other nanoparticle systems including magnetic and semiconductor nanoparticles. With some of these materials, shape and size can be easily controlled, and we will aim to understand their impact on intermolecular interactions.
While EPR is likely to be the main tool for this study, other in situ methods will also be used as appropriate, (e.g., NMR, other types of spectroscopy, calorimetry).
The project is very interdisciplinary and will provide ample opportunities for learning new techniques for which training will be provided. At the start of the project, some organic and nanoparticle synthesis and characterization will be needed. Later in the project, training in advanced EPR spectroscopy and other analytical techniques will be provided. All Chemistry research students have access to our innovative Doctoral Training in Chemistry (iDTC): cohort-based training to support the development of scientific, transferable and employability skills: https://www.york.ac.uk/chemistry/postgraduate/cdts/
The Department of Chemistry holds an Athena SWAN Gold Award and is committed to supporting equality and diversity for all staff and students. The Department strives to provide a working environment which allows all staff and students to contribute fully, to flourish, and to excel: https://www.york.ac.uk/chemistry/ed/.
For more information about the project, click on the supervisor's name above to email the supervisor. For more information about the application process or funding, please click on email institution
This PhD will formally start on 1 October 2022. Induction activities may start a few days earlier.
To apply for this project, submit an online PhD in Chemistry application:
You should hold or expect to achieve the equivalent of at least a UK upper second class degree in Chemistry or a related subject.