Sensitive and rapid biosensor for the determination of rhamnose based on the catalytic effect of the oxidation of calcein by H₂O₂

Abstract

We report a new catalytic biosensor for the detection of rhamnose (Rha) based on combining the high sensitivity of a fluorescence method with the high selectivity of a catalytic reaction.

Tuneable Time Delay in the Burst Release from Oxidation‐Sensitive Polymersomes Made by PISA

“…As H 2 O 2 causes an oxidation‐induced fluorescence quenching, free calcein was investigated under similar conditions as a reference. [29] In the case of the calcein‐loaded vesicles ( V1‐3‐C ) in H 2 O 2 a comparable continuous decrease in fluorescence intensity was observed at early stages. This continuous quenching of the encapsulated calcein, similar to free calcein, corroborates the above‐mentioned free diffusion of H 2 O 2 across the vesicular membrane.…”

“…: 510–540 nm; Figure 4 B) over time. As H 2 O 2 causes an oxidation‐induced fluorescence quenching, free calcein was investigated under similar conditions as a reference [29] . In the case of the calcein‐loaded vesicles ( V1‐3‐C ) in H 2 O 2 a comparable continuous decrease in fluorescence intensity was observed at early stages.…”

“…causes an oxidation-induced fluorescence quenching, free calcein was investigated under similar conditions as ar eference. [29] In the case of the calcein-loaded vesicles (V1-3-C)in H 2 O 2 ac omparable continuous decrease in fluorescence intensity was observed at early stages.T his continuous quenching of the encapsulated calcein, similar to free calcein, corroborates the above-mentioned free diffusion of H 2 O 2 across the vesicular membrane.After aspecific time for each tested sample,t he release of calcein could be detected by ad istinct increase in fluorescence intensity (Figure 4B). Similar to the T 1/2 values described above,t he release shifts to later time points for larger PNAT blocks and correlates well with the onsets of membrane degradation of the unloaded vesicles V1-2.W ea ssume that the delay in V3 is related to adecrease of the H 2 O 2 concentration in presence of the dye,but it nevertheless shows asimilar release pattern.…”

Kontrollierbare Zeitverzögerung beim Aufplatzen von oxidationsempfindlichen, mittels PISA synthetisierten Polymersomen

“…: 510–540 nm; Abbildung 4 B) über die Zeit beobachtet wurde. Da H 2 O 2 eine oxidationsbedingte Fluoreszenzabschwächung bewirkt, wurde freies Calcein unter gleichen Bedingungen als Referenz untersucht [29] . Im Falle der mit Calcein beladenen Vesikel ( V1‐3‐C ) in H 2 O 2 wurde eine vergleichbare kontinuierliche Abnahme der Fluoreszenzintensität in den Anfangsphasen beobachtet.…”