Research interests

Interfacial adsorption is of critical importance in many industrial and biological processes, primarily due to the fact that system properties such as flocculation, flotation and biological recognition may be modified by interaction with an interface of miniscule amounts of surface-active species such as polyelectrolytes (proteins) and surfactants (lipids). Whilst the surface excess of the adsorbate is often of importance in inducing behavioral change, structural properties such as the polar orientation and degree of conformational order are also critical. A great deal of research has been performed on quantifying the effect of variables such as concentration of the surface-active species, electrolyte concentration, pH and temperature on surface excess. Comparatively little work however has focused on determining the effect of the same system properties on the detailed structure of the adsorbed layer. The primary reason for this paucity of data is the lack of techniques capable of providing interface specific structural information. The aim of our research is to determine detailed conformational informational of interfacial species in industrially and biologically relevant systems with the intention of gaining insight into how the surface structure affects the properties of the system. The primary technique employed is the surface specific second order non-linear optical technique of Sum Frequency vibrational Spectroscopy (SFS). This high energy laser technique involves overlapping, both spatially and temporally, a visible beam of fixed frequency and an infrared beam of tunable frequency on an interface. A third beam is emitted from the interface, the frequency of which is the sum of the two incident frequencies. Detecting this emitted light as function of the infrared wavelength produces a vibrational spectrum that is upshifted into the visible. The polar orientation of species resident at the interface is determined from the relative phase of the resonance signal, that is, whether 'peaks' or 'dips' are observed in the spectrum. Conformational information of the species is reflected by the relative strength of the resonance signals. The detailed structural information of interfacial species obtained by SFS is complemented by information obtained by a range of other surface techniques in order to provide a more complete picture of the interface. Specifically, the surface excess of the adsorbate is determined by appropriate linear transmission or reflection spectroscopies, for example UV-visible transmission and infrared attenuated total reflection. Further, extensive use of Atomic Force Microscopy is made in order to associate the surface excess and structural information with interfacial topography.

Current projects Include:

Cellulose Based Substrates for Interfacial Adsorption Studies This project is aimed at the development of cellulose based substrates which may be probed spectroscopically by both linear and non-linear optical techniques. The optimized substrates will be employed to elucidate interfacial adsorption on cellulosic surfaces in systems relevant to the pulp and paper industry. The main requirement of the substrates is one of optical flatness, an issue that will be addressed by the construction of composite substrates comprising a thin layer of cellulose supported on a suitable optical element. Determination of the surface excess of a polyelectrolyte or surfactant of interest on the cellulose layer will be achieved by selecting a supporting material that is transmitting in the spectral region required. This will allow either ex-situ transmission or in-situ Attenuated Total Reflection, ATR, measurements to be made. Conformational studies of the adsorbates will be performed by Sum Frequency vibrational Spectroscopy, SFS. Gold will be employed as the support substrate for the thin cellulose layer in the SF experiments due to the favorable non-linear optical response of this metal.

Conformational Studies of Lipid Molecules Comprising Model Membranes Biological membranes consist of a bilayer of primarily lipid molecules which contain a polar headgroup and two pendent hydrocarbon chains. The conformational structure of the alkyl chains of the lipid is known to influence membrane properties such as the rigidity, the degree of in-plane fluidity and trans membrane transport phenomena. However, detailed studies precisely characterising the structural effects of lipids on membrane properties are complicated by the difficulty of deconvoluting the complex native systems. Consequently there is a strong need for a model membrane system that accurately reproduces the characteristics of a native membrane and that may be studied by techniques that yield conformational information. This project aims to construct asymmetric membranes consisting of two different lipid molecules each in a separate layer of the bilayer. The degree of conformational order of the alkyl chains of the lipids will then be determined under a wide range of conditions by application of Sum Frequency vibrational Spectroscopy (SFS).

Publications

• Review Articles: 1. † Lambert, A.G.; Davies, P.B.; Neivandt, D.J. “Implementing the Theory of Sum Frequency Generation Vibrational Spectroscopy: A Tutorial Review” Appl. Spect. Reviews 40, 103 (2005) 2. † Prudovsky, I. ; Tarantini, F. ; Landriscina, M. ; Neivandt, D. ; Soldi, R. ; Kirov, A. ; Small, D. ; Kathir, K.M. ; Rajalingam, D. ; Kumar, T.K. “Secretion without Golgi” Journal of Cellular Biochemistry 103, 1327 (2008) Articles: 3. † Wark, M. ; Kalanyan, B. ; Ellis, L. ; Fick, J. ; Connell, L. : Neivandt, D. ; Vetelino J. “A Lateral Field Excited Acoustic Wave Sensor for the Detection of Saxitoxin in Water”, Ultrasonics Syposium 2007, IEEE, 1217 (2007) 4. † Oporto, G. S. ; Gardner, D. J. ; Bernhardt, G. ; Neivandt, D. J. “Characterizing the Mechanism of Improved Adhesion on Modified Wood Plastic Composites (WPC) Surfaces”, Journal of Adhesion Science and Technology 21, 1097 (2007) 5. † Gramlich, W. M. ; Gardner, D. J. ; Neivandt, D. J. “Surface Treatments of Wood Plastic Composites (WPC) to Improve Adhesion”, Journal of Adhesion Science and Technology 20, 1873 (2006) Primary author, Gramlich, was an undergraduate student 6. † Graziani, I. ; Bagala, C. ; Duarte, M. ; Soldi, R. ; Kolev, V. ; Tarantini, F. ; Kumar, S. ; Doyle, A. ; Neivandt, D. ; Yu, C. Maciag, T. ; Prudovsky, I. “Release of FGF1 and p40 Synaptotagmin 1 Correlates with their Membrane Destabilizing Ability”, Biochemical and Biophysical Research Communications 349, 192 (2006) 7. † Casford, M.T.L. ; Davies, P.B. ; Neivandt, D.J. “Adsorption of Sodium Dodecyl Sulfate at the Hydrophobic Solid/Aqueous Solution Interface in the Presence of Poly(ethyleneglycol): Dependence upon Polymer Molecular Weight”, Langmuir 22, 3005 (2006) 8. † McGall, S.J. ; Davies, P.B. ; Neivandt, D.J. “Development of a Biologically Relevant Calcium Phosphate Substrate for Sum Frequency Generation (SFG) Vibrational Spectroscopy”, J. Phys. Chem. A 109, 8745 (2005) 9. † Holman, J. ; Davies, P. B. ; Nishida, T. ; Ye, S. ; Neivandt, D. J. “Sum Frequency Generation from Langmuir Blodgett Multilayer Films on Metal and Dielectric Substrates” J. Phys. Chem. B. 109, 18723 (2005) Feature and Cover Article 10. † Poirier, J. S. ; Tripp, C. P. ; Neivandt, D. J. “Templated Surfactant Re-Adsorption on Polyelectrolyte Induced Depleted Surfactant Surfaces” Langmuir 21, 2876 (2005) 11. † Doyle, A. W. ; Fick, J. ; Himmelhaus, M. ; Eck, W. ; Graziani, I. ; Prudovsky, I. ; Grunze, M. ; Maciag, T. ; Neivandt, D. J. “Protein Deformation of Lipid Hybrid Bilayer Membranes studied by Sum Frequency Generation Vibrational Spectroscopy (SFS)” Langmuir 20, 8961 (2004) 12. † Holman, J. ; Ye, S.; Neivandt, D.J. ; Davies, P.B “Studying Nanoparticle-Induced Structural Changes Within Fatty Acid Multilayer Films Using Sum Frequency Generation Vibrational Spectroscopy” J.A.C.S. 126, 14322 (2004) 13. † McGall, S.J. ; Davies, P.B. ; Neivandt, D.J. “Interference Effects in Sum Frequency Generation Vibrational Spectra of Thin Polymer Films: an Experimental and Theoretical Investigation ”, J. Phys. Chem. B. 108, 16030 (2004) 14. † Holman, J. ; Neivandt, D.J. ; Davies, P.B. “Nanoscale Interference Effect in Sum Frequency Generation from Langmuir-Blodgett Fatty Acid Films on Hydrophobic Gold”, Chem. Phys. Letts. 386, 60 (2004) 15. † Holman, J. ; Davies, P.B. ; Neivandt, D.J. “Sum Frequency Spectroscopy of Langmuir-Blodgett Fatty Acid Films on Hydrophobic Gold”, J. Phys. Chem. B. 108, 1396 (2004) 16. † Casford, M.T.L. ; Davies, P.B. ; Neivandt, D.J. “A Study of the Co-Adsorption of an Anionic Surfactant and an Uncharged Polymer at the Aqueous Solution/Hydrophobic Interface by Sum Frequency Spectroscopy”, Langmuir 19, 7396 (2003) 17. † McGall, S.J. ; Davies, P.B. ; Neivandt, D. J. “Sum Frequency Vibrational Spectroscopy of the Comb Copolymer Cetyl Dimethicone Copolyol”, J. Phys. Chem. B. 107, 4718 (2003) 18. ‡ Lambert, A.G. ; Neivandt, D.J. ; Briggs, A.M. ; Usadi, E.W. ; Davies, P.B. “Enhanced Sum Frequency Generation from a Monolayer Adsorbed on a Composite Dielectric/Metal Substrate”, J. Phys. Chem. B. 106, 10693 (2002) 19. ‡ Lambert, A.G. ; Neivandt, D.J. ; Briggs, A.M. ; Usadi, E.W. ; Davies, P.B. “Interference Effects in Sum Frequency Spectra from Monolayers on Composite Dielectric/Metal Substrates”, J. Phys. Chem. B., 106, 5461 (2002) Cover Article 20. ‡ Windsor, R. ; Neivandt, D.J. ; Davies, P.B. “Temperature and pH effects on the Co-Adsorption of Sodium Dodecyl Sulfate and Poly(ethylenimine)”, Langmuir, 18, 2199 (2002) 21. ‡ Windsor, R. ; Neivandt, D.J. ; Davies, P.B. “Adsorption of Sodium Dodecyl Sulfate in the presence of Poly(ethylenimine) and Sodium Chloride studied using Sum Frequency Vibrational Spectroscopy”, Langmuir, 17, 7306 (2001)

Community/University Service

Co-Chair GSBS Admissions Committee

UMaine representative on the GSBS Stearing Committee