The research by Kulczynska, Frost, and Margerum is entitled Effect of PAMAM Dendrimer Size and pH on the Electrostatic Binding of Metal Complexes Using Cyclic Voltammetry. It is an applied research which employs the use of cyclic voltammetry (CV) as a technique in validating its hypothesis. The objective of the research is “to develop an easy technique for detecting differences in small molecule binding to dendrimers in buffered solutions” (Kulczynska, Frost, and Margerum 7372).
Using Starburst polyamidoamine dendrimers with an ethylenediamine core and crystalline potassium ferrocyanide, the research methodology involves a cyclic voltammetry “inside a Faraday cage with single compartment cells and a […] potentiostat” (Kulczynska et al. 7372). Apart from the cyclic voltammetry, the researchers also made use of basic titration and performed the redox process among the materials and solutions. The significance of the research is to “draw upon established methods that use voltammetry to measure electrostatic and hydrophobic binding between polyelectrolytes” (Kulczynska et al. 7372).
It tests the hypothesis and further aims to “establish extent of electrostatic binding of probes” to other possible researches. The main points found by the researchers include the following results: First, the dendrimer causes binding of the higher charged probe form which, in turn, causes the higher peak potentials of the CV; and conversely, the slower diffusion of the dendrimer causes a reduced probe coefficient which decreases the peak potentials of the CV. The research also strengthens the polyelectrolyte theory wherein the higher binding constant produces stronger electrostatic binding.
However, it was seen that “the shift in formal potentials with generation must be due to changes in the physical properties of the macromolecule” (Kulczynska et al. 7374). The intrinsic properties of the molecule give a significant change in the binding process. Furthermore, the study exposed that the lower pH level, at pH 5, produces a much larger potential shift of the dendrimer as compared to pH 7. The larger potential shift also causes larger binding ratios, better electron transfer reversibility, and stronger binding constants for pH 5.
In summary, “the 4- ion [PAMAM dendrimer] binds much more strongly than the 3- ion at pH 5 than at pH 7” (Kulczynska et al. 7374). The research does not contain any inconsistencies as the researchers have already forewarned that several assumptions are still being led and the research topic is still in the process of further studies. They mentioned that “while it is not clear which effect may prevail [4- probe responding to additional charged sites in the dendrimer interior, or the binding model ignoring effects that may shift equilibrium binding to favor the 4- ion], the dendritic molecule becomes more close-packed”(Kulczynska et al.
7375). They also revealed that “many questions remain on the effect of size, functional group, buffer type, and pH on the binding of small molecules to dendrimers” (Kulczynska et al. 7376), but their findings could be useful in succeeding researches on dendrimer polyelectrolytes. Conclusively, the researchers were able to support the main points that they established in the discussion and results section. They used electrochemical methods in investigating electrostatic binding of PAMAM dendrimers with focus on the effect of dendrimer generation and pH level variables.
The result supports that “the binding ratios obtained from CV potential shifts are an indicator of charge density for the PAMAM dendrimer series” (Kulczynska et al. 7376). Several similar researches were used as bases of comparison and analysis regarding the study. Work Cited Kulczynska, Agnieszka, Tony Frost, and Lawrence D. Margerum. “Effect of PAMAM Dendrimer Size and pH on the Electrostatic Binding of Metal Complexes Using Cyclic Voltammetry. ” Macromolecules 39 (2006): 7372-7377.
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