My research interests lie in the exploitation of green nanotechnology, engineering and synthesis for the generation of innovative nano- and biomaterials for alternative energy, biomedical, and environmental applications. My masters project obtained fundamental insight on the molecular interactions of model drug isomers in SC CO₂ fluid media ¹. In my doctoral studies, I have developed novel supercritical (SC) deposition methods to synthesize effectively metal (Pt, Ru) nanoparticles (1-20 nm) supported on various nanoporous substrates such as carbon and silica aerogels with potential application as fuel cell electrocatalysts. The resulting nanocomposites were characterized by TEM, SEM, XRD, TGA, Physisorption and Chemisorption Analyses, FTIR, GC-MS and membrane electrode assembly (MEA) testing.^2-5 In a collaborative project, techniques were developed to prepare stabilized drug-loaded biodegradable polymeric nanoparticles for drug delivery and foams for medical devices using supercritical fluids. The morphology and composition of drug-loaded polymeric nanoparticles by TEM, SEM and HPLC, and the physical properties of the foam by sorption, SEM and OM techniques were evaluated.^6-7 In this project, I also successfully performed ring opening polymerizations to synthesize biodegradable poly(lactic acid) and poly(lactic-co-glycolic acid) in SC CO₂ and CHClF₂ at different temperatures, pressures and catalyst concentrations and characterized the polymerization products by NMR and GPC techniques. In my postdoctoral work, one set of projects focused on the (1) extraction of lignin from woody biomass ⁸, (2) use of novel supercritical gas and gas-expanded liquids to perform oxidations on this biomass to produce high-value chemicals and potential biofuels ⁹ and (3) use of SC CO₂ in the solubilization of amino acids and polypeptides via reverse micelle formation that has an attractive implication on protein processing such as separation from and impregnation into solid matrices.¹⁰ Another set of project in my postdoctoral research involves the use of the electrospinning method to fabricate porous ^11-12 functional and hybrid nanofibers¹³ for various applications such as wound dressing¹⁴ , tissue scaffolds¹⁵ , drug delivery ¹⁶, filtration for capture and recovery of toxic metals¹⁷ and catalysis of nitrophenolic compounds¹⁸ . A few highlights of my contribution through these projects are (1) the development of a one-step green process in the generation of electrospun nanoparticle-nanofiber composites with the use of the electrospinning polymer as the reductant and stabilizer for the nanoparticles at ambient conditions, that is, without the use of usually toxic reducing agent or the application of external energy (2) the utilization of surfactants to aid in the electrospinnability of difficult-to-electrospin polysaccharides and the use of sacrificial species for the formation of porous nanofibers and (3) the coupling of atomic layer deposition and electrostatic self-assembly with electrospinning to generate hybrid nanofibers.

References

1.“Steric effects and preferential interactions in supercritical CO₂” C.D. Saquing, F.P. Lucien and N.R. Foster. Ind Eng Chem Res, 1998, 37, 4190-4197.

2.“Preparation of platinum/carbon aerogel nanocomposites using a supercritical deposition method” C.D. Saquing, T.T. Cheng, M. Aindow and C. Erkey. J Phys Chem B, 2004, 108, 7716-7722.

3. “Investigation of the supercritical deposition of platinum nanoparticles into carbon aerogels” C.D. Saquing, D. Kang, M. Aindow and C. Erkey. Micropor Mesopor Mater, 2005, 80, 11-23.

4. “Supported platinum nanoparticles by supercritical deposition” Y. Zhang, D. Kang, C.D. Saquing, M. Aindow and C. Erkey. Ind Eng Chem Res, 2005, 44, 4161-4164.

5. “High-resolution TEM characterization of carbon aerogels as catalyst supports”, D. Kang, Y. Zhang, C.D. Saquing, C. Erkey and M. Aindow. Mater Res Soc Symp Proc, 2003, 800, 367-372.

6. “Preparation of drug delivery biodegradable PLGA nanocomposites and foams by supercritical CO₂ expanded ROP and by rapid expansion from CHClF₂ supercritical solutions” A.D. Asandei, C. Erkey, D.J. Burgess, C.D. Saquing, G. Saha and B.S. Zolnik, Mater Res Soc Symp Proc, 2005, 845 (Nanoscale Materials Science in Biology and Medicine), 243-248.

7. “Preparation of Drug-Biodegradable Polymer Nanocomposites for Drug Delivery via Rapid Expansion from Supercritical Solutions”, with A.D. Asandei, C. Erkey, D.J. Burgess, G. Saha and B.S. Zolnik, ACS Polymer Preprints, 2004, 45(2), 770.

8. “Toward a better understanding of the lignin isolation process from wood” A. Guerra, I. Filpponen, L.A. Lucia, C.D. Saquing, S. Baumberger, D.S. Argyropoulos. J. Agric. Food Chem. 54, 5939 -5947, 2006.

9. “Oxidative chemistry of lignin in supercritical carbon dioxide & expanded liquids” C.D. Saquing, D.S. Argyropoulos, A.R. Gaspar, N.U.Soriano, L.A. Lucia, O.J. Rojas, Materials,Chemicals and Energy from Forest Biomass, Argyropoulos, D. S., Ed., ACS Symposium Ser., Washington, DC. Book Chapter, 2006.

10. “Solubilizing amino acids and polypeptides in supercritical carbon dioxide via reverse micelle formation” N.U. Soriano, R. Venditti, C.D. Saquing, D. Bushey, D.S. Argyropoulos. Colloids and Surfaces A: Physicochem. Eng. Aspects, 2008, 315, 110–116.

11. “Preparation and characterization of silica nanoparticulate–polyacrylonitrile composite and porous nanofibers” L. Ji, C.D. Saquing, S.A. Khan and X. Zhang, Nanotechnology, 19 (085605), 2008.

12. “Porous nylon 6 fibers via a novel salt-induced electrospinning method” A. Gupta.; M. Afshari C.D. Saquing, R. Kotek, S.A. Khan, X. Zhang, A. Tonelli. in preparation for submission to Macromolecules (draft available)

13. “Metal nanoparticles-loaded Al₂O₃ microtubes by atomic layer deposition on electrospun nanofiber templates” C.D. Saquing, Q. Peng, J. Manasco, G. Parsons and S.A. Khan. in preparation. [A portion of this paper was presented at the 235th ACS Spring National Mtg, New Orleans, LA, Apr 6-10, 2008.]

14. “Electrospun nanoparticle-nanofiber composites with the electrospinning polymer as reducing, protecting and templating agent” C.D. Saquing, J. Manasco, and S.A. Khan, in preparation for submission to Nano Letters (draft available). [This paper was presented at the AIChE 2007 Annual Meeting, Salt Lake City, UT, Nov 3-9, 2007.]

15. “Surfactant-assisted electrospun alginate-based polymer blend nanofibers for biomedical applications” C.D. Saquing, J. Manasco, J. M. Saquing, C. Bonino, F. delos Reyes and S.A. Khan, in preparation for submission to Biomacromolecules. [This paper was presented at the 235th ACS Spring National Mtg, New Orleans, LA, Apr 6-10, 2008.]

16. High throughput nanofiber production via electrospinning of polycaprolactone melts” J. Manasco, C.D. Saquing, S. Talwar, J. Hinestroza, and S.A. Khan, in preparation for submission to Macromolecules (draft available) [This paper was presented at the 235th ACS Spring National Mtg., New Orleans, LA, Apr 6-10, 2008.]

17. "Polysaccharide-based polymer blend nanofibers for environmental applications” C.D. Saquing, J. M. Saquing, F. delos Reyes and S.A. Khan, in preparation.

18. “pH activated nanoparticle self-assembly in polymer nanofiber surfaces as catalysts for nitrophenolic compounds” C.D. Saquing, J. Genzer and S.A. Khan, in preparation for submission to Adv Materials.