Facile Synthesis of Prussian Blue-Filled Multiwalled Carbon Nanotubes Nanocomposites: Exploring Filling/Electrochemistry/Mass-Transfer in Nanochannels and Cooperative Biosensing Mode

Abstract

We report on mild and selective filling of multiwalled carbon nanotubes (MWCNTs) with Prussian blue (PB) to explore the filling/electrochemistry/mass-transfer in nanochannels and the biosensing mode of nanochannel interior-exterior cooperation. PB-filled MWCNTs (MWCNTs-PB in ) are prepared by filling MWCNTs with the gradually growing PB and then selectively removing the outersurface PB by careful chemical washing. The prepared MWCNTs-PB in composites possess high filling yield (mass ratio of PB to MWCNTs, (30 ± 3)%) and electroactivity percentage (mass ratio of electroactive PB to total PB, (45 ± 3)%). The MWCNTs-PB in composites on Au electrode exhibit strong and stable electrocatalytic activity of filled PB for H 2 O 2 reduction and electroanalysis. The filling of the MWCNTs with electroactive PB also provides a new experimental platform to deal with the widely concerned issue of mass transfer inside nanochannels. The normalized cyclic voltammetric responses of filled PB on MWCNTs-PB in electrode at relatively low scan rates (below 125 and 75 mV s −1 for mass transfer of K + and K + + H 2 O 2 , respectively) were found to be equivalent to those of conventionally electrodeposited PB on MWCNTs/Au and Au electrodes, demonstrating that the mass transfer of K + and H 2 O 2 inside our MWCNTs is comparable to those outside our MWCNTs at the low scan rates. Furthermore, the unoccupied outer surfaces of MWCNTs-PB in are conveniently exploited to bind 4-(1-pyrenyl) butyric acid through π−π stacking interaction and then to anchor glucose oxidase or lactate oxidase through the EDC/NHS chemistry. Thus, we have developed a novel cooperative biosensing mode by combining outer-surface biocatalyzed oxidation of substrate with interior PB-catalyzed reduction of enzymatically generated H 2 O 2 , which endows our biosensors with low detection potential (−0.1 V) and satisfactory sensitivity/selectivity.

A comparative study of different protein immobilization methods for the construction of an efficient nano-structured lactate oxidase-SWCNT-biosensor

“…To provide evidence that demonstrate that the protein was actually covalently immobilized, we studied each step of the biosensor assembly and the covalent immobilization of the enzyme LOx onto the SWCNT-based biosensor by XPS. One paper in the literature reports the covalently immobilization of LOx onto a CNT-sensor using the linker EDC but no XPS or other experimental evidence directly support the covalent immobilization (Wang et al 2012). …”

“…Different papers report on the immobilization of LOx onto CNTs by adsorption (e.g., sol-gel) (Huang et al 2008; Goran et al 2011; Haghighi and Bozorgzadeh 2011; Taurino et al 2013), by covalent immobilization with glutaraldehyde (Yamamoto et al 2003), or by using the popular cross-linker EDC (Wang et al 2012). Despite the fact that LOx has been covalently immobilized frequently onto carbon nanomaterials, there is still a lack of detailed studies investigating the structural, functional, and stability consequences of this.…”

Bio-inspired porous antenna-like nanocube/nanowire heterostructure as ultra-sensitive cellular interfaces

“…Compared with pristine TiO 2 NWs that have negligible absorption in the visible range, the ultraviolet-visible spectra of the PB-TiO 2 antenna NWs show a substantial absorption increase in the range of 500 À900 nm with a maximum at 714 nm, which corresponds to the inter-metal charge transfer bands from Fe 2 þ to Fe 3 þ in PB nanocrystals (Figure 3b). 25 The corresponding energy dispersive X-ray analysis of the PB-TiO 2 NWs shows clear Fe and Ti signals (Supplementary Figure S5). The growth of PB-TiO 2 antenna NWs is further demonstrated by the infrared spectra.…”

“…No redox peaks except for the capacitive current are observed for the pristine TiO 2 NW electrode, whereas the PB-TiO 2 antenna NW electrode has a pair of redox peaks at 0.23 and 0.18 V (Figure 4a), which corresponds to the reversible conversion of PB to Prussian white. 25 The scan rate dependency for the voltammetry profile of the PB-TiO 2 antenna NW electrode in the range 50 À1000 mV s À1 is then presented (Figure 4b), in which the electrochemical stability of the PB-TiO 2 antenna NWs is demonstrated by repeating cyclic voltammetry measurements at a scan rate of 50 mV s À1 . There is no observable difference in either current level or peak positions for the cyclic voltammetry curves after 50 cycles (Figure 4c), which confirms the stable structure of the immobilized PB nanocubes on the TiO 2 NW tips.…”

Ni-Co bimetal nanowires filled multiwalled carbon nanotubes for the highly sensitive and selective non-enzymatic glucose sensor applications

“…Initially, the primary development of electrochemical quantification of glucose was vastly relied upon the performances of specific biocatalysis of enzymes including glucose oxidase (GOx) and glucose dehydrogenase (GDH). The definite immobilization of enzymes and direct exposure of their redox active sites toward glucose offered the sufficient sensitivity and selectivity, which were optimal for the clinical practice in diabetes management78. However, the denaturation of enzymes during the electrode fabrication, storage and exploitation, high sensitivity toward temperature, pH and humidity, poor reproducibility and high cost, turn out to be the significant constrains of enzymatic glucose sensors, which directed the research domains toward the exploration of non-enzymatic glucose sensors comprising metal nanocatalysts.…”