Chemical Force Spectroscopy on single living cells E. Dague, D. Alsteens, J.P. Latgé, Y. Dufrêne

Kaminsky et al., Mycological Research Aspergillus hyphae and conidia as seen by SEM

Classical way of probing microbial hydrophobicity Hydrophobicity – MATH, MATS – HIC – Adhesion test – Contact angle Not specific of hydrophobic character and under electrostatic interactions influence (Mozes, Rouxhet 1987 ; van Loosdrecht et al., 1990 ; Gaboriaud et al., 2006) vortex 1 min

Increasing CH 3 surface fraction Probing hydrophobic forces at the nanoscale

Alsteens, Dague et al., Langmuir % CH 3 75 % CH 3 50 % CH 3 25 % CH 3 0 % CH 3 Frequency (%) Adhesion force (nN) Hydrophobicity calibration Hydrophobicity quantification and calibration Surface fraction CH 3 (%) Adhesion force (nN) 3 (%)

Single Aspergillus conidia trapped in a pore as seen by contact mode AFM 500 nm sample holder membrane water single cell tape

100 nm 1000 pN Adhesion force (pN) Hydrophobic Force Microscopy of A. fumigatus Frequency (%) Dal : native 100 nm

Dal : native Dal + NaOH 1M 100 nm

Dal : native Dal + NaOH 1M Mutant without hydrophobins 100 nm Dague, Alsteens et al., Nanoletters 2007

100 nm

Adhesion force map revealing highly correlated structural and hydrophobic heterogeneities 100 nm Dague, Alsteens et al., Nanoletters 2007

Kaminsky et al., Mycological Research Aspergillus hyphae and conidia as seen by SEM

Germination Real time imaging of conidia during germination Dague et al., Biophysical Journal 2007

0 min 20 min 120 min180 min 60 min 120 min 200 nm Structural dynamics of single germinating conidia

0 min 60 min 180 min 90 min 120 min 210 min 100 nm 200 nm 100 nm 200nm 100 nm Evolution of hydrophobicity with germination time Dague et al., Biophysical Journal 2007

Hydrophobicity can be probed and quantified at the nanoscale Direct visualization of correlated morphological and chemical evolution Biological process (germination), chemical modifications can be observed, in real time Take Home Message

Y. DufrêneD. AlsteensJ.P. Latgé

Chemical Force Spectroscopy on single living cells E. Dague, D. Alsteens, J.P. Latgé, Y. Dufrêne

Toward a global bio-surface analysis : Combined use of AFM, XPS and SIMS Dague et al., Langmuir 2008 AB CD Dal Rod B Rod A Rod AB Intensity (a. u.) XPS N peak WT ∆RodB ∆RodA∆RodA ∆RodB Normalized intensities i/i tot C 2 H 3 O 2 - NI, SIMS CN - NI, SIMS