Electrochemistry of Non-Redox-Active Poly(propylenimine) and Poly(amidoamine) Dendrimers at Liquid−Liquid Interfaces

Abstract

The electrochemistry of a series of dendrimers was examined at the interface between two immiscible electrolyte solutions (ITIES), enabling study of non-redox-active dendrimers. Different generations of poly(propylenimine) (DAB-AM-n) and poly(amidoamine) (PAMAM) dendrimers were studied. In their protonated states, the dendrimers were transferred across the ITIES, with the electrochemical behavior observed depending on the dendrimer family, the generation number, and the experimental pH. The electrochemistry of the lower generations studied was characterized by well-defined peaks for both dendrimer families and with small peak-peak separations in the case of the PAMAM family. The voltammetry of the higher generations was more complex, showing distorted voltammograms and instability of the interface. The charges of the transferring dendrimers were calculated by convolution of the voltammetric data and were similar to the theoretical charges for DAB-AM-n. For PAMAM, only the lowest generation exhibited reversible behavior, with higher generations having irreversible behavior. Using cyclic voltammetry, low micromolar concentrations of the dendrimers were detected. The results show that electrochemistry at the ITIES can be a useful method for characterization of ionizable dendrimers and that voltammetry can be a simple method for detection of low concentrations of these multicharged species.

Spectroelectrochemical Characterization of Dendrimer–Porphyrin Associates at Polarized Liquid|Liquid Interfaces

“…As reported previously, the positive peak observed around 0.40 V assigned as ion transfer of the G4 PAMAM dendrimer from the aqueous to the organic phases, and negative peak around 0.30 V as the back transfer from the organic to the aqueous phases. 16,32 In addition, a gradual increase of current response at the positive edge of the potential window Figure S8). The absence of apparent transfer responses in the corresponding potential region would demonstrate that the porphyrin molecules are stably associated with the dendrimers even at the polarized water|DCE interface.…”

Electrochemical behaviour of denatured haemoglobin at the liquid|liquid interface

“…Amongst these, electrochemistry at polarised liquid|liquid interfaces has been used for the investigation of non-redox electrochemistry [2,3] and electroanalytical determination [4] of a range of ions. Recently, a variety of large polycationic molecules have been studied at the liquid|liquid interface, EC09-2006, revised 16Dec2009 2 including dendrimers [5], peptides [6] and proteins [7][8][9][10][11][12][13][14][15][16][17][18][19][20]. We have recently investigated the electrochemical behaviour of haemoglobin [15][16][17], insulin [18] and lysozyme [19] at the liquid | liquid interface.…”

Flow-injection amperometry at microfabricated silicon-based μ-liquid–liquid interface arrays

“…Inducing the transfer of ions across the interface between two immiscible electrolyte solutions (ITIES) by generating a potential difference between the two phases provides a powerful avenue for the detection of non-redox active species [1][2][3][4][5][6][7][8][9][10][11]. Flow injection analysis (FIA) of numerous charged species using a variety of electrochemical detection techniques (e.g.…”