The application of asymmetic-flow field flow fractionation (A4F) for low aspect ratio gold nanorod (GNR) fractionation and characterization was comprehensively investigated.  We report on two novel aspects of this application. First, the capacity for A4F to fractionate positively charged nanoparticles (with pH in the range 3 to 4) was demonstrated.  The problem of irreversible absorption of psitively charged nanoparticles onto the A4F accumulation wall (negatively charged membrane) can be eliminated by controlling the mobile phase composition (e.g., the ratio between ammonium nitrate and CTAB, and ionic strength).  The optimized condition affords a convenient retention time associated wih the highest possible recovery.  The second aspect is the demonstration of shape-based separation of GNRs in A4F normal mode elution.  We described and validated an A4F methodology that permits eluting GNRs according to their aspect ratio.  We believe this to be the first reported experimental study to clearly show the steric-entropic contribution of nanoparticle shape to the elution process by FFF, where GNR diffusion coefficient, aspect ration and orientation vector control elution in normal mode A4F.  Finally, we applied the developed methodoldogy to fractionate GNR components within a complex mixture containing different aspect ratios.  The results show that multi-wavlenght optical absorbance detection can be relevant to interpret the shape of GNRs according to their retetention time in A4F.  The combination of absorbance detection with A4F has the advantage of in situe analysis to investigate GNR aspect ratio and to separate individual popluations.

Gold nanorod separation and characterization by asymmetric-flow field flow fractionation coupled to UV-Vis detector

245th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.