Research Interests

My research is at the interface of materials chemistry, analytical chemistry, and nanotechnology.

1. Development of solid phase extraction, separation, compound identification and quantification techniques using HPLC-QTOF, and CE-QTOF and QQQ
2. Development of hyphenated size-based separation techniques (e.g., asymmetric field flow fractionation, centrifugal field flow fractionation, capillary electrophoresis, liquid chromatography) using spectrometry (QTOF/QQQ), MALS, DLS and optical absorbance detectors.
3. Collaboration on projects with other Office of Regulatory Affairs Laboratories and FDA Centers where nanomaterials need to be detected and/or quantified.
4. Development of hyphenated size-based separation techniques using asymmetric flow field flow fractionation, centrifugal field flow fractionation, inductively coupled plasma/mass spectrometry (ICP/MS), light scattering detectors and conductivity detector
5. Development of hyphenated size-based separation and speciation techniques using capillary electrophoresis, inductively coupled plasma/mass spectrometry (ICP/MS)

Proposed Research Project for an FDA Commissioner's Fellow

The selected fellow will work on the physical and chemical characterization of selected innovator (brand name) - generic nano-drug pairs and evaluate any physical and/or chemical differences between two classes. Fellow will collaborate with ORA NanoCore scientists and CDER to develop techniques to separate nanoparticle drugs based on size as well as techniques to quantify the concentration of the active pharmaceutical ingredient and to analyze any excipients such as lipids, PEG, buffer and chemical composition. The selected fellow will use solid phase extraction and high resolution mass spectrometry to identify and quantify chemical impurities including byproducts of the active pharmaceutical ingredients and unlabeled trace level lipids.

Experimental design and selection of priority area will be determined based on need of ORA drug labs and CDER. As results of experimentation, validated regulatory characterization methods will be developed and transferred to the ORA labs.

Applicant Requirements

Ph.D. in chemistry, materials science, physics or related field, with a strong emphasis in mass spectrometry. The candidate should ideally have experience in the identification and quantitation of polymers and small molecules including lipids using HPLC– MS/MS and HPLC ELSD/CAD, or other current published methodologies.

Selected Recent Publications

1. Haiou Qu, Sean W. Linder, Thilak K. Mudalige*, “Surface coating and matrix effect on the electrophoretic mobility of gold nanoparticles: a capillary electrophoresis-inductively coupled plasma mass spectrometry study”, Analytical and Bioanalytical Chemistry, 2016 , ASAP, DOI 10.1007/s00216-016-0012-0
2. Thilak K. Mudalige*, Haiou Qu, Sean W. Linder*, “An Improved Methodology of Asymmetric Flow Field Flow Fractionation Hyphenated with Inductively Coupled Mass Spectrometry for the Determination of Size Distribution Gold Nanoparticles in Dietary Supplements”, Journal of Chromatography A, 2015, 1420, 92–97
3. Thilak K. Mudalige*, Haiou Qu, Sean W. Linder*, “Asymmetric Flow Field Flow Fractionation Hyphenated ICP-MS as an Alternative to Cloud Point Extraction for Quantification of Silver Nanoparticles and Silver Speciation: Application for Nanoparticles with Protein Corona”, Analytical Chemistry, 2015 87, 7395–7401
4. Thilak K. Mudalige* Haiou Qu, Germarie Sanchez-Pomales, Patrick N. Sisco, Sean W. Linder*, “Simple Functionalization Strategies for Enhancing Nanoparticle Separation and Recovery with Asymmetric Flow Field Flow Fractionation”, Analytical Chemistry, 2015, 87 (3), pp 1764–1772