1- Investigation of Polyamidoamine Dendrimer Induced DNA Condensation and enzymatic degredation of these complexes: An Atomic Force Microscopy (AFM) Study

Despite much progress in the drug-delivery field, there remain a number of well-known obstacles to the development of such systems. To help overcome these challenges, we proposed that a deeper understanding of the detailed structure of proposed vector complexes and their response to environmental challenges would be of great benefit in this rational design. In the course of this study, we have demonstrated this philosophy using atomic force microscopy (AFM) to visualize and characterize, at the molecular scale and in near in-situ conditions the effect of the dendrimer generations, incubation times with DNA, the presence and absence of surfaces during the complex formation, presence and absence of soluble polymer cations, relative proportions of (G4, G6 and G8) molecules on the morphology of the formed DNA-PAMAM dendrimer complexes and the afforded degree of protection from enzymatic degradation. In addition we have investigated the behaviours of the G4 PAMAM dendrimers on different alkanethiol self assembled monolayers in liquid (in near in-situ conditions) and in air using the AFM as a force measuring (force-distance measurements and amplitude phase distance measurements) and imaging tool.

2- Investigating the long rang fractal of C60 Fullerenes using dynamic force microscopy.

3- Investigating the effect of gamma cyclodextrin on the morphology of single walled carbon nano-tubes using AFM.

4- AFM investigation of dendrimers-metal complexes.

1. Direct real time molecular scale visualization of the degradation of condensed DNA complexes exposed to DNase I. Hosam G. Abdelhady, Stephanie Allen, Martyn C. Davies, Clive J. Roberts, Saul J.B. Tendler & Philip M. Williams. Nucleic Acid Research. 31(14) 2003, 4001-4005.

2. Polyethylenimine as non-viral carriers for aerosol gene therapy: Investigations of complex stability and characterization by AFM.

E. Kleemann, L.A. Dailey, H. Petersen, H.G. Abdelhady, C.J. Roberts, M.C. Davies, T. Schmehl, T. Gessler, W. Seeger, T. Kissel., Proc. Intern. Symp. Control. Rel. Bioact. Mater. 30 (2003) 593-594.

3. Atomic Force Microscopy Studies of Generation 4 Poly (amidoamine) (PAMAM) Dendrimers on Functionalized Surfaces. Hosam G. Abdelhady, Stephanie Allen, Martyn C. Davies, Clive J. Roberts, Saul J.B. Tendler & Philip M. Williams. Surface Science 558, 2004, 99–110.

4. Direct atomic force microscopy observations of monovalent ion induced binding of DNA to mica. Ellis, J.S*., Abdelhady, HG, Allen, S., Davies, MC., Tendler, SJB, Williams PM & Roberts, Journal of Microscopy, 215, 2004 297-301.(joint first author).

5. Modified polyethylenimines as non-viral gene delivery systems for aerosol gene therapy: investigations of the complex structure and stability during air-jet and ultrasonic nebulization. E. Kleemann, L. A. Dailey, H. G. Abdelhady, T. Gessler, T. Schmehl, C. J. Roberts, M. C. Davies, W. Seeger, T. Kissel. .Journal of Controlled Release 100, 2004, 437–450.

7. Towards nanoscale metrology for biomolecular imaging by atomic force microscopy. Hosam G. Abdelhady, Stephanie Allen†, Stephen J. Ebbens, Claire Madden, Nikin Patel, Clive J. Roberts and Jianxin Zhang. Nanotechnology 16 (2005) 966-973.

8. Enhanced pulmonary gene expression is facilitated by low toxicity of low-molecular-weight polyethylenimine under in vivo conditions. E. Kleemann, N. Jekel, L. A. Dailey, H. G. Abdelhady, L. Fink, N. Weismann, R. Schermuly, T. Gessler, T. Schmehl, C. J. Roberts, W. Seeger, T. Kissel. Submitted to: The Journal of Gene Medicine, 2005.