Herein,
fluorescent gold nanoclusters (AuNCs) and horseradish peroxidase
(HRP) were simultaneously embedded into self-assembled dipeptide supramolecular
films of N-fluorenylmethoxycarbonyl diphenylalanine
(Fmoc-FF) on the surface of ITO electrodes (Fmoc-FF/AuNCs/HRP) by
using a simple single-step process. In the films, both the fluorescence
property of AuNCs and the bioelectrocatalytic property of HRP were
well maintained and could be reversibly regulated by pH-sensitive
structural changes in the Fmoc-FF hydrogel films. Cu(II)/EDTA in the
solution could lead to the aggregation/disaggregation of AuNCs and
further quenching/dequenching the fluorescence signal from the films.
Meanwhile, the blue complexes formed by Cu(II) and EDTA could produce
a UV–vis signal in the solution. In addition, the coordinated
Cu(II) in the films enhanced the electrocatalytic capacity toward
the reduction of H2O2 and could switch the current
signal. A biomolecular logic circuit was built based on the smart
film electrode system by using pH, the concentrations of EDTA, Cu(II)
and H2O2 as inputs, while the fluorescence intensity
(FL), current (I) and UV–vis extinction (E) of the solution as outputs. Various logic devices were
fabricated using the uniform platform, consisting of an encoder/decoder,
demultiplexer, dual-transfer gate, keypad lock, digital comparator,
half adder, and controlled NOT (CNOT) gate. Specifically, an electronic
three-value logic gate, gullibility (ANY) gate, was
first mimicked in this biocomputing system. This work not only demonstrated
the construction of a new type of multivalued logic gate by using
a dipeptide micromolecular matrix but also provided a new approach
for designing sophisticated biologic functions, establishing smart
multianalyte biosensing or fabricating biology information processing
through the use of a simple film system.
Glycosaminoglycans
(GAGs) contribute to the treatment of many human
diseases, especially in the field of thrombosis, because of their
anticoagulant activity. GAGs interrupt the coagulation process by
interacting with multiple coagulation factors through defined sequences
within their linear and negatively charged chains, which are not fully
elucidated. Numerous methods have been developed to characterize the
structure of pharmaceutical GAGs, including intravenously or subcutaneously administered heparin and orally
administered sulodexide. However, most currently available methods
only focus on the oligosaccharide portion or analyze the whole mixture
because longer-chain polysaccharides are extremely difficult to resolve
by chromatographic separation. We have established two novel electrophoresis–mass
spectrometry methods to provide a panoramic view of the structures
of pharmaceutical GAGs. In the first method, an in-gel digestion procedure
was developed to recover GAGs from the polyacrylamide gels, while
in the second method, a strong anion exchange ultrafiltration procedure
was developed to extract multiple GAG species from the agarose gels.
Both procedures are compatible with liquid chromatography–tandem
mass spectrometry, and structural information, such as disaccharide
composition and chain length, can be revealed for each GAG fraction.
The applications of these two methods on analysis of two different
GAG drugs, heparin and sulodexide, were demonstrated. The current
study offers the first robust tool to directly elucidate the structure
of larger GAG chains with more biological importance rather than obtaining
a vague picture of all chains as a mixture, which is fundamental for
better understanding the structure–activity relationship and
quality control of the GAG drugs.
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