Chemical addition of specific lariats to cyclodextrin-based supramolecular complexes

Review of research efforts reveals that PBA – Fc solubility issues can be addressed by the use of β-cyclodextrins (β-CDs); a hypothesis that has been proven to improve the solubility of ferrocene. Explicably, research has further shown that CDs can selectively bind different hydrophobic guest-molecules forming a supramolecular complex in aqueous environment. With the goal being to build on this, Sophia University researchers: Maria Antonietta Casulli (PhD candidate), Dr. Takeshi Hashimoto, Professor Takashi Hayashita, in collaboration with Dr. Irene Taurino and Professor Sandro Carrara, at the Federal Institute of Technology in Switzerland, developed a novel electrochemical assay for an extremely-selective detection of fructose thanks to the use of a supramolecular complex between β-cyclodextrins (β-CDs) and a chemically modified ferrocene with boronic acid named 4-Fc-PB/natural-β-CDs. In addition, they also proposed another kind of β-CDs, the 4-Fc-PB/3-phenylboronic-β-CDs, for the detection of glucose. Their work is currently published in the research journal, Small.

The novelty of their approach consisted in the role of CDs which, for the first time, were employed in electrochemistry with a unique detection mechanism based on specific chemical interactions with the target molecule by the introduction of proper binding groups. In general, the developed system performance was evaluated from the decrease of voltammetric peak currents for sensing fructose and glucose thanks to the combination of the two assays.

The authors reported that going by their approach, CDs were actively involved, for the first time ever, in a specific-chemical interaction with the target molecule for an electrochemical sensing. Overall, a highly selective detection of fructose was obtained. The researchers further reported that the proposed mechanism of detection represented a new means to electrochemically sense other molecules by altering the combination of specific groups of the supramolecular complex. As confirm of it, they have already demonstrated that just by changing the specific bonding group of CDs and using the same 4-FC-PB probe, it was possible to selectively detect ATP (scientific paper published in: https://doi.org/10.1021/acsabm.1c00166 ACS Appl. Bio Mater. 2021, 4, 4, 3041–3045).

In summary, the study demonstrated the successful synthesis of novel 4-Fc-PB electrochemical probe, that achieved an extremely selective detection of fructose thanks to the formation of a supramolecular complex with natural β-cyclodextrins. Moreover, the study further demonstrated the use of 4-Fc-PB/3-phenylboronic acids β-CDs (3-PB-β-CDs) supramolecular complex for sensitive detection of glucose. Remarkably, by combining the two developed supramolecular complexes, it was seen possible to selectively detect the glucose. In a statement to Advances in Engineering, first author, Maria Antonietta Casulli explained that their findings are of impactful importance since a quick, easy, cheap, and extremely selective detection of fructose is not yet to be developed, but with their approach, success is in sight.

QUOTE FROM THE AUTHOR (Maria Antonietta Casulli):

We are aware that we have only just opened a door that needs to be better explored. But we have already demonstrated the effectiveness of our idea, managing to selectively measure ATP by functionalizing the cyclodextrins with a dipicolylamine group instead of the phenylboronic acid one. For these reasons, we have good hopes to believe that we can recognize many other types of molecules such as proteins, bacteria and, now as never before, viruses. Moreover, our intention is to take advantage of typical potentials offered by electrochemistry, such as nanotechnologies or appropriate CMOS design, to develop real sensors based on these methods. We are just getting started!