Wednesday, June 16, 2021, 1:30 pm

Hosted by: Vivian Stojanoff

An odyssey in drug delivery study via X-ray microscopy approach We've used X-ray fluorescence microscopy (XRF) as a powerful chemical nano-imaging tool to study a few examples of anti-cancer drug with transition metal complexes (Os, Ir) and locate their target sites within human cancer cells. Throughout these studies, despite its high sensitivity, semi-quantitative, and versatility, XRF has also complemented other techniques such as soft X-ray microscopy, TEM, cryo light confocal microscopy, and hard X-ray phase contrast imaging to provide more complete pictures to uncover the potential delivery mechanisms. In addition, sample preparations including cryogenic preparation, as well as the transfer compatibility between various techniques, as a critical aspect, will also be discussed.

Friday, June 18, 2021, 10:00 am

Hosted by: Gregory Doerk

Two-dimensional (2D) materials have attracted great attention during the last decade, benefitting from their rich variety of chemical and crystal structures defining unique physical and chemical properties overall outperforming traditional nanomaterials. More specifically, the electronic and optical properties could either be tuned by varying the atomic combinations and structural motif, or by varying the number of layers in the same type of material. The ultra-flat surface makes it facile for 2D materials to stack up with each other, forming Van der Waals heterostructures which could serve as active materials of elementary unit in electronic devices such as FETs and p-n junctions. Apart from the intrinsic high-performances of 2D materials as semiconductors, their large surface-to-volume ratio and flat surfaces enables them to interact actively with the local environment, including neighbouring organic molecules. These molecules, either physisorbed or chemisorbed on the surface of 2D semiconductors, are able to markedly influence the properties of the latter component. This talk will introduce the interactions between organic species and 2D semiconducting materials (transition metal dichalcogenides, black phosphorus, indium selenide) in the following aspects: i) fundamental physico-chemical properties of the organic-2D material heterostructure. ii) fabrication and characterizations of molecular functionalized electronic devices and potential applications.

Monday, June 21, 2021, 1:00 pm

Hosted by: Gregory Doerk

Semiconducting carbon nanomaterials have attracted significant attention in recent decades due to their unique electronic, mechanical, optical, thermal, and chemical properties. Single-walled carbon nanotubes (SWNTs) is a 1D nanomaterial that has found versatile applications in material research and device fabrication for sensing, transistors, photovoltaics, and other electronics. Biosensors are the critical element in diagnostic devices for many diseases. Field-effect transistor (FET) biosensor utilizing SWNTs as the transducing element shows high sensitivity and specificity compared to optical and electrochemical biosensors. However, the major challenge is the high cost and complicated procedures of the traditional fabrication of FET biosensors on silicon wafers, which can be unaffordable in low-resource settings. To overcome the challenge, I utilized the inkjet printing technology to pattern the SWNTs-based FET sensor arrays on paper-based microfluidics. This approach has improved both the sensing performance and the affordability of FET biosensors. In this presentation, I will present my recent research advances on inkjet-printing patterned paper-based FET biosensors. Firstly, to maximize the semiconductor with higher aqueous solubility and higher bioconjugation capacity, a zero-length linker 1-pyrene carboxylic acid (PCA) was used for the non-covalent functionalization of SWNTs. The synthesis of PCA/SWNTs resulted in a high solubility of the semiconductors in a water-based solution up to 4 mg/mL. Material characterizations were conducted for the PCA/SWNTs complex. Secondly, the water-based semiconductor solution was formulated as inkjet-printable inks for precise deposition on the paper substrate to pattern the FET sensor arrays. Various ink formulations were developed for different functional nanomaterials that retained the bioactivity of the bioreceptor and met the rheological requirements for stable inkjet printing. The SWNTs percolation profile was characterized to identify the optimum network density and provide the highest biosensing sensitivity. Thirdly, the cost-effective paper-based microfluidics was programmed and optimized with fluid delay and acceleration functions to automate the solution delivery. The paper-based FET biosensor arrays patterned by the inkjet-printed SWNTs were optimized, quantified, and assembled to detect multiple disease biomarker molecules at ultralow concentrations, including proteins and micro RNAs, fitting the needs for affordable point-of-care use for disease diagnosis.