Presentation Information
[P01-025]Ultrathin Gold Nanoparticles for the Highly Effective Replacement of Biological Enzymes
○Joseph Fox1, Nizzy James1, George Newham1, Evans Stephen1 (1. University of Leeds (UK))
Keywords:
nanoparticles,nanozymes,diagnostics,gold,enzymatic
Purpose
Biological enzymes such as horseradish peroxidase (HRP) are widely used in sensing platforms including ELISAs, but suffer from limited stability under varying temperature, pH and solvent conditions. In contrast, nanozymes - nanomaterials that mimic enzyme activity – offer improved chemical and storage stability alongside reduced production costs. Our group has developed a simple, room temperature, seedless synthesis method for fabricating structurally unique gold nanoparticles with diverse spectral and morphological characteristics. These include quasi-1D gold nanotapes (AuNT), 2D gold nanosheets (AuNS), and hierarchical 3D gold nanopinecones (AuNPC)1-4. These particles exhibit exceptional stability, catalytic activity2 and lateral flow assay performance1. Here, we evaluate their potential to replace biological enzymes in diagnostic systems.
Methods
AuNS, AuNT and AuNPC were produced by reducing chloroauric acid with trisodium citrate in the presence of methyl orange. Morphologies were controlled by adjusting synthesis conditions. Nanoparticles were characterised by spectroscopy and TEM. Nanozyme performance of gold nanoparticles was assessed using common diagnostic substrates in solution and upon immobilisation within PVA-hydrogels.
Results
The gold nanomaterials demonstrated robust nanozyme activity, effectively replacing HRP in the oxidation of diagnostic substrates TMB, DAB and Amplex Red (AR)1-3. Among the materials tested, AuNT (length ~35 nm) were particularly effective nanozymes, with their ultrathin 2D-3D morphology, accessible surface atoms and high edge-to-volume ratio resulting in ~28-fold greater catalytic activity than spherical AuNP2. AuNT-AR sensors for quantification of H2O2 and glucose were developed and integrated into PVA hydrogels, enabling glucose detection down to 50µM and effective operation across the physiologically relevant sweat glucose range.
Consideration
Our nanomaterials function as highly active enzyme-replacing nanozymes in multiple diagnostic systems, outperforming spherical AuNP and conventional biological enzymes. The integration of these nanoparticles into AuNT-AR sensing systems for the detection of H2O2 and glucose, demonstrates their utility in solution and as flexible PVA-hydrogel sensors. AuNT-AR hydrogel sensors can be pre-loaded with all required reagents and cast directly into well plates, enabling a simple, reagent-integrated workflow where users simply add sample, which is particularly attractive for emerging wearable diagnostic systems.
Conclusion
This work highlights AuNS, AuNPC and AuNT as high-performance alternatives to conventional AuNP and biological enzymes for next-generation diagnostic applications.
Fox et al., ACS Appl. Nano Mater. 2023, 6 (19), 17769-17777
Newham, G.; Fox et al., Mater. Res. Express. 2023, 10 (6), 064001
Ye et al., Adv. Sci. 2019, 6 (21), 1900911
Fox et al., J. Phys. Chem. C 2023, 127 (6), 3067-3076
Biological enzymes such as horseradish peroxidase (HRP) are widely used in sensing platforms including ELISAs, but suffer from limited stability under varying temperature, pH and solvent conditions. In contrast, nanozymes - nanomaterials that mimic enzyme activity – offer improved chemical and storage stability alongside reduced production costs. Our group has developed a simple, room temperature, seedless synthesis method for fabricating structurally unique gold nanoparticles with diverse spectral and morphological characteristics. These include quasi-1D gold nanotapes (AuNT), 2D gold nanosheets (AuNS), and hierarchical 3D gold nanopinecones (AuNPC)1-4. These particles exhibit exceptional stability, catalytic activity2 and lateral flow assay performance1. Here, we evaluate their potential to replace biological enzymes in diagnostic systems.
Methods
AuNS, AuNT and AuNPC were produced by reducing chloroauric acid with trisodium citrate in the presence of methyl orange. Morphologies were controlled by adjusting synthesis conditions. Nanoparticles were characterised by spectroscopy and TEM. Nanozyme performance of gold nanoparticles was assessed using common diagnostic substrates in solution and upon immobilisation within PVA-hydrogels.
Results
The gold nanomaterials demonstrated robust nanozyme activity, effectively replacing HRP in the oxidation of diagnostic substrates TMB, DAB and Amplex Red (AR)1-3. Among the materials tested, AuNT (length ~35 nm) were particularly effective nanozymes, with their ultrathin 2D-3D morphology, accessible surface atoms and high edge-to-volume ratio resulting in ~28-fold greater catalytic activity than spherical AuNP2. AuNT-AR sensors for quantification of H2O2 and glucose were developed and integrated into PVA hydrogels, enabling glucose detection down to 50µM and effective operation across the physiologically relevant sweat glucose range.
Consideration
Our nanomaterials function as highly active enzyme-replacing nanozymes in multiple diagnostic systems, outperforming spherical AuNP and conventional biological enzymes. The integration of these nanoparticles into AuNT-AR sensing systems for the detection of H2O2 and glucose, demonstrates their utility in solution and as flexible PVA-hydrogel sensors. AuNT-AR hydrogel sensors can be pre-loaded with all required reagents and cast directly into well plates, enabling a simple, reagent-integrated workflow where users simply add sample, which is particularly attractive for emerging wearable diagnostic systems.
Conclusion
This work highlights AuNS, AuNPC and AuNT as high-performance alternatives to conventional AuNP and biological enzymes for next-generation diagnostic applications.
Fox et al., ACS Appl. Nano Mater. 2023, 6 (19), 17769-17777
Newham, G.; Fox et al., Mater. Res. Express. 2023, 10 (6), 064001
Ye et al., Adv. Sci. 2019, 6 (21), 1900911
Fox et al., J. Phys. Chem. C 2023, 127 (6), 3067-3076
Comment
To browse or post comments, you must log in.Log in