During recent decades, nucleic acid aptamers have emerged as powerful biological recognition elements for electrochemical affinity biosensors. These bioreceptors emulate or improve on antibody-based ...biosensors because of their excellent characteristics as bioreceptors, including limitless selection capacity for a large variety of analytes, easy and cost-effective production, high stability and reproducibility, simple chemical modification, stable and oriented immobilization on electrode surfaces, enhanced target affinity and selectivity, and possibility to design them in target-sensitive 3D folded structures. This review provides an overview of the state of the art of electrochemical aptasensor technology, focusing on novel aptamer-based electroanalytical assay configurations and providing examples to illustrate the different possibilities. Future prospects for this technology are also discussed.
Graphical abstract
Novel Janus nanoparticles based on Au colloids anisotropically modified with polyamidoamine dendrons were prepared though a masking/toposelective modification approach. These nanomaterials were ...further functionalized with horseradish peroxidase on the dendritic face and provided on the opposite metal surface with a ssDNA aptamer for C-reactive protein (CRP). The resulting nanoparticles were employed as biorecognition/signaling elements to construct an amperometric aptasensor with sandwich-type architecture for the specific detection of this cardiac biomarker. To do this, screen-printed carbon electrodes modified with electrodeposited Au nanoparticles and functionalized with anti-CRP aptamers were used as transduction interface. The aptasensor was employed for the amperometric detection of CRP (working potential: − 200 mV vs pseudo-Ag/AgCl) in the broad range from 10 pg·mL
−1
to 1.0 ng·mL
−1
with a detection limit of 3.1 pg·mL
−1
. This electroanalytical device also showed good specificity, reproducibility (RSD = 9.8%,
n
= 10), and stability and was useful to quantify CRP in reconstituted human serum samples, with a RSD of 13.3%.
Graphical abstract
'Communication' between abiotic nanoscale chemical systems is an almost-unexplored field with enormous potential. Here we show the design and preparation of a chemical communication system based on ...enzyme-powered Janus nanoparticles, which mimics an interactive model of communication. Cargo delivery from one nanoparticle is governed by the biunivocal communication with another nanoparticle, which involves two enzymatic processes and the interchange of chemical messengers. The conceptual idea of establishing communication between nanodevices opens the opportunity to develop complex nanoscale systems capable of sharing information and cooperating.
Citrus peel pectin was used to prepare films (cast with or without glycerol) containing mesoporous silica nanoparticles. Nanoparticles reduced significantly the particle size, and had no effect on ...the Zeta potential of pectin solutions. Mechanical characterization demonstrates that pectin+nanoparticles containing films slightly increased tensile strength and significantly decreased the Young's modulus in comparison to films made only of pectin. However, elongation at the break increased in the pectin+nanoparticles films cast in the presence of glycerol, while both Young's modulus and tensile strength were reduced. Moreover, nanoparticles were able to reduce the barrier properties of pectin films prepared with or without glycerol, whereas positively affected the thermal stability of pectin films and the seal strength. The 0.6% pectin films reinforced or not with 3% nanoparticles in the presence of 30% glycerol were used to wrap strawberries in order to extend the fruit's shelf-life, over a period of eighty days, by improving their physicochemical properties.
Strategies to maximize direct electron transfer (DET) between redox enzymes and electrodes include the oriented immobilization of enzymes onto an electroactive surface. Here, we present a strategy ...for achieving a controlled orientation of a fungal laccase on carbon nanotube-based electrodes. A homogeneous population of pyrene-modified laccase is obtained via the reductive amination of a unique surface accessible lysine residue engineered near the T1 copper center of the enzyme. Immobilization of the site-specific functionalized enzyme is achieved either via π-stacking of pyrene on pristine CNT electrodes or through pyrene/β-cyclodextrin host guest interactions on β-cyclodextrin-modified gold nanoparticles (β-CD-AuNPs). Contrasting with unmodified and nonspecifically modified (pyrene-NHS) laccase-electrodes, an efficient DET is obtained at these nanostructured assemblies. Modeling the direct bioelectrocatalysis of dioxygen reduction reveals a heterogeneity in ET rates on MWCNT electrodes wheras β-CD-AuNPs act as efficient electronic bridges, lowering ET rate dispersion and achieving a highly efficient reduction of O2 at low overpotential (≈80 mV) accompanied by high catalytic current densities of almost 3 mA cm–2.
We report herein the design of an autonomous glucose-responsive smart nanomachine for insulin (In) delivery based on ultrasound (US)-propelled nanomotors combined with an enzyme-based ...sensing-effector unit. Gold nanowire (AuNW) motors have been coupled with a mesoporous silica (MS) segment, which was gated with pH-responsive phenylboronic acid (PBA)-glucose oxidase (GOx) supramolecular nanovalves responsible for the insulin release. Glucose-induced protonation of the PBA groups triggers the opening of the pH-driven gate and uncapping of the insulin-loaded nanovalves. The insulin-loaded MS-Au nanomotors displayed an efficient US-driven movement that dramatically accelerates the glucose-triggered insulin release when compared to their static counterparts. Such coupling of the locomotion of nanovehicles with gated insulin-containing nanocontainers and glucose-responsive nanovalves holds great promise for the improved management of diabetes.
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•Novel avidin/imminobiotin-mechanized mesoporous silica nanoparticles.•Signal amplification approach for electrochemical aptasensor.•Sensitive aptasensor for carcinoembryonic antigen.
...We report herein a novel sensing strategy for electrochemical biosensors, by using mesoporous silica nanoparticles loaded with the redox probe methylene blue and capped with an avidin/imminobiotin stimulus-responsive gate-like ensemble as signal amplification element. As a proof of concept, an aptasensor for carcinoembryonic antigen (CEA) was constructed by attaching a biotin and thiol-functionalized anti-CEA DNA hairpin aptamer on gold nanoparticles modified carbon screen-printed electrodes. The biosensing approach relied on the unfolding of the aptamer molecule after specific recognition of CEA, unmasking the biotin residue and allowing further association with the avidin-capped mesoporous nanocarrier. Incubation with H2SO4 trigger the release of the encapsulated redox probe allowing the detection of the cancer biomarker from 1.0 pg/mL to 160 ng/mL.
This study describes the production of reinforced polysaccharide (PS)-based films, by adding mesoporous silica nanoparticles (MSNs), to either pectin (PEC) or chitosan (CH) film forming solutions, ...either containing glycerol (GLY) as a plasticizer, or not. Film characterization demonstrated that MSNs and GLY were able to significantly increase the plasticity of both PS-based biomaterials and that the interactions between PSs and nanoparticles were mainly due to hydrogen bonds. Moreover, MSN-containing films were less transparent, compared to controls prepared with either PEC or CH, in the absence of GLY, while all films containing MSNs, but obtained with the plasticizer, were as transparent as the films prepared with PEC or CH alone. MSN addition did not influence the thickness of the PEC-based films, but increased that of CH-based ones, prepared both in the absence and presence of GLY. MSN-containing PEC-based films possessed a more compact and homogeneous morphology, with respect to both control films, prepared, with or without GLY, and to the CH-based films, containing MSNs, the structure of which showed numerous agglomerations. Finally, moisture content and uptake were reduced, in all films prepared in the presence of MSNs. The suggested addition of MSNs might have given rise to novel biomaterials for food or pharmaceutical applications.
Here we report a novel labeling strategy for electrochemical aptasensors based on enzymatic marking via supramolecular host–guest interactions. This approach relies on the use of an ...adamantane-modified target-responsive hairpin DNA aptamer as an affinity bioreceptor, and a neoglycoconjugate of β-cyclodextin (CD) covalently attached to a redox enzyme as a labeling element. As a proof of concept, an amperometric aptasensor for a carcinoembryonic antigen was assembled on screen-printed carbon electrodes modified with electrodeposited fern-like gold nanoparticles/graphene oxide and, by using a horseradish peroxidase-CD neoglycoenzyme as a biocatalytic redox label. This aptasensor was able to detect the biomarker in the concentration range from 10 pg/mL to 1 ng/mL with a high selectivity and a low detection limit of 3.1 pg/mL in human serum samples.
A novel nanostructured architecture for the construction of electrochemical enzyme biosensors is here described. It implies the electrostatic layer‐by‐layer assembly of four‐generation ...ethylenediamine core polyamidoamine G‐4 dendrimers on glassy carbon electrodes coated with a graphene oxide‐carboxymethylcellulose hybrid nanomaterial. This modified surface was further employed for the covalent immobilization of the model enzyme tyrosinase through a glutaraldehyde‐mediated cross‐linking. The prepared enzyme electrode allowed the amperometric detection of catechol in the 2–400 nM range. The biosensor showed excellent analytical performance with high sensitivity of 6.3 A/M and low detection limit of 0.9 nM. The enzyme electrode retained over 93 % of the initial activity after 40 days at 4 °C.
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