“…The I 208 / I 248 ratio for PBA-CD (0.99) was observed to be lower than that for the PBA compound (without CD, 1.47), indicating a local molecular symmetry change in the [Co(CN) 6 ] fragment modifying the electronic transition moment for PBA-CD. Indeed, we observed an increase in the baseline for both nanomaterials due to the presence of nano-sized cubes, as the total light absorbance is the sum of the absorbed radiation (σ abs ) and scattered radiation (σ sca ) according to the Mie law [42]. The formation of the hybrid nanomaterial was also evidenced by the Tyndall effect, as shown in the inset of Figure 2.…”
Supramolecular self-assembly has been demonstrated to be a useful approach to developing new functional nanomaterials. In this work, we used a cobalt Prussian blue analogue (PBA, Co3[Co(CN)6]2) compound and a β-cyclodextrin (CD) macrocycle to develop a novel host-guest PBA-CD nanomaterial. The preparation of the functional magnetic material involved the self-assembly of CD molecules onto a PBA surface by a co-precipitation method. According to transmission electronic microscopy results, PBA-CD exhibited a polydisperse structure composed of 3D nanocubes with a mean edge length of 85 nm, which became shorter after CD incorporation. The supramolecular arrangement and structural, crystalline and thermal properties of the hybrid material were studied in detail by vibrational and electronic spectroscopies and X-ray diffraction. The cyclic voltammogram of the hybrid material in a 0.1 mol·L−1 NaCl supporting electrolyte exhibited a quasi-reversible redox process, attributed to Co2+/Co3+ conversion, with an E1/2 value of 0.46 V (vs. SCE), with higher reversibility observed for the system in the presence of CD. The standard rate constants for PBA and PBA-CD were determined to be 0.07 and 0.13 s−1, respectively, which suggests that the interaction between the nanocubes and CD at the supramolecular level improves electron transfer. We expect that the properties observed for the hybrid material make it a potential candidate for (bio)sensing designs with a desirable capability for drug delivery.
“…The I 208 / I 248 ratio for PBA-CD (0.99) was observed to be lower than that for the PBA compound (without CD, 1.47), indicating a local molecular symmetry change in the [Co(CN) 6 ] fragment modifying the electronic transition moment for PBA-CD. Indeed, we observed an increase in the baseline for both nanomaterials due to the presence of nano-sized cubes, as the total light absorbance is the sum of the absorbed radiation (σ abs ) and scattered radiation (σ sca ) according to the Mie law [42]. The formation of the hybrid nanomaterial was also evidenced by the Tyndall effect, as shown in the inset of Figure 2.…”
Supramolecular self-assembly has been demonstrated to be a useful approach to developing new functional nanomaterials. In this work, we used a cobalt Prussian blue analogue (PBA, Co3[Co(CN)6]2) compound and a β-cyclodextrin (CD) macrocycle to develop a novel host-guest PBA-CD nanomaterial. The preparation of the functional magnetic material involved the self-assembly of CD molecules onto a PBA surface by a co-precipitation method. According to transmission electronic microscopy results, PBA-CD exhibited a polydisperse structure composed of 3D nanocubes with a mean edge length of 85 nm, which became shorter after CD incorporation. The supramolecular arrangement and structural, crystalline and thermal properties of the hybrid material were studied in detail by vibrational and electronic spectroscopies and X-ray diffraction. The cyclic voltammogram of the hybrid material in a 0.1 mol·L−1 NaCl supporting electrolyte exhibited a quasi-reversible redox process, attributed to Co2+/Co3+ conversion, with an E1/2 value of 0.46 V (vs. SCE), with higher reversibility observed for the system in the presence of CD. The standard rate constants for PBA and PBA-CD were determined to be 0.07 and 0.13 s−1, respectively, which suggests that the interaction between the nanocubes and CD at the supramolecular level improves electron transfer. We expect that the properties observed for the hybrid material make it a potential candidate for (bio)sensing designs with a desirable capability for drug delivery.
“…In magneto electrochemistry, the catalysts and redox mediators immobilized on magnetite particles can be carried by magnetic fields to the surface of an electrode making feasible a switchable control of faradaic current from catalysis. As an example, Melo et al synthesized of a new material composed by magnetite modified with insoluble ferrocene and chitosan cross-linked with glucose oxidase (Fe 3 O 4 -Chi-Fc/GOx) [45]. The authors observed an increase of 70% of the electrical current generated by the catalysis of GOx.…”
Section: Resultsmentioning
confidence: 99%
“…Figure 6.Magneto electrochemistry of Fe 3 O 4 -CTAB-Fc. The electroactivity was determined in the ‘switch off’ (red line) ‘switch on’ (green line) modes in the configuration I of Melo et al [45]. ( a ) Cyclic voltammograms of Fe 3 O 4 -CTAB-Fc at 100 mV s −1 obtained at ‘switch on’ (green line) and ‘switch off’ modes (black line).…”
Liposomes containing magnetic nanoparticles (magnetoliposomes) have been extensively explored for targeted drug delivery. However, the magnetic effect of nanoparticles movement is also an attractive choice for the conduction of signals in communication systems at the nanoscale level because of the simple manipulation and efficient control. Here, we propose a model for the transmission of electrical and luminous signals taking advantage of magnetophoresis. The study involved three steps. Firstly, magnetite was synthesized and incorporated into fusogenic large unilamellar vesicles (LUVs) previously associated with a fluorescent label. Secondly, the fluorescent magnetite-containing LUVs delivered their contents to the giant unilamellar vesicles (GUVs), which were corroborated by magnetophoresis and fluorescence microscopy. In the third step, magnetophoresis of magnetic vesicles was used for the conduction of the luminous signal from a capillary to an optical fibre connected to a fluorescence detector. Also, the magnetophoresis effects on subsequent transmission of the electrochemical signal were demonstrated using magnetite associated with CTAB micelles modified with ferrocene. We glimpse that these magnetic supramolecular systems can be applied in micro- and nanoscale communication systems.
“…135 A simple approach with two switchable modes, switch on and switch off, was used to induce the electrochemical current from an enzymatic reaction. 140 The simultaneous control of biocatalytic reactions with two enzymes was reported by Katz et al, with GOx and lactate dehydrogenase (LDH). 138 Liang et al produced a magneto-controlled bioelectrocatalytic system for glucose oxidation, in which ferrocene was grafted to the thiol-terminated Fe 3 O 4 nanoparticles via a UV-induced thiolene click reaction.…”
Clinical diagnosis has always been dependent on the efficient immobilization of biomolecules in solid matrices with preserved activity, but significant developments have taken place in recent years with the increasing control of molecular architecture in organized films. Of particular importance is the synergy achieved with distinct materials such as nanoparticles, antibodies, enzymes, and other nanostructures, forming structures organized on the nanoscale. In this review, emphasis will be placed on nanomaterials for biosensing based on molecular recognition, where the recognition element may be an enzyme, DNA, RNA, catalytic antibody, aptamer, and labeled biomolecule. All of these elements may be assembled in nanostructured films, whose layer-by-layer nature is essential for combining different properties in the same device. Sensing can be done with a number of optical, electrical, and electrochemical methods, which may also rely on nanostructures for enhanced performance, as is the case of reporting nanoparticles in bioelectronics devices. The successful design of such devices requires investigation of interface properties of functionalized surfaces, for which a variety of experimental and theoretical methods have been used. Because diagnosis involves the acquisition of large amounts of data, statistical and computational methods are now in widespread use, and one may envisage an integrated expert system where information from different sources may be mined to generate the diagnostics.
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