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Rapid and Selective Discrimination of Gram-Positive and Gram-Negative Bacteria by Boronic Acid-Modified Poly(amidoamine) Dendrimer

Tsuchido, Yuji, Horiuchi, Ryosuke, Hashimoto, Takeshi, Ishihara, Kanako, Kanzawa, Nobuyuki, Hayashita, Takashi
Analytical chemistry 2019 v.91 no.6 pp. 3929-3935
Gram-negative bacteria, Gram-positive bacteria, antibiotics, crosslinking, dendrimers, drug resistance, fructose, moieties, pH, phenylboronic acids
There is an urgent need to develop a rapid and selective method for the detection of bacteria because delayed diagnosis and the overuse of antibiotics have triggered drug resistance in bacteria. To this end, we prepared boronic acid-modified poly(amidoamine) generation 4 (B-PAMAM(G4)) dendrimer as cross-linking molecules that form aggregates with bacteria. Within 5 min of adding B-PAMAM(G4) dendrimer solution to a bacterial suspension, large aggregates were observed. Interestingly, the aggregate formation with various bacteria was pH-dependent. In basic pH, both Gram-positive and Gram-negative bacteria formed aggregates, but in neutral pH, only Gram-positive bacteria formed aggregates. We revealed that this bacteria-selective aggregation involved the bacterial surface recognition of the phenylboronic acid moiety of B-PAMAM(G4) dendrimer. In addition, we demonstrated that the spherical structure of B-PAMAM(G4) was one of the important factors for the formation of large aggregates. The aggregation was also observed in the presence of ≤10 mM fructose. B-PAMAM(G4) dendrimer is expected to be a powerful tool for the rapid and selective discrimination between Gram-positive and Gram-negative bacteria.