Convective Flow-Assisted Catalytic Propulsion of Polymer Beads Coated with Pd Nanoparticles for the Detection of Enzyme Inhibitors and Industrial Effluents

Abstract

Ultrasensitive detection of enzyme inhibitors and heavy metal contaminants in effluents constitutes a major interdisciplinary research area. Multiple methods based on colorimetry, conductance measurement, reactivity estimation, etc., have been developed in this direction, which often involve the use of sophisticated equipment and complex methodologies. Herein, we present a simple, table-top technique for the detection of enzyme inhibitors and industrial effluents using convective flow-assisted propulsion of catalytic palladium nanoparticle (NP)-coated polymer motors in solution. The motors display buoyancy-driven self-propulsion, which is further enhanced in the presence of secondary catalysts like catalase and horseradish peroxidase, generating auxiliary convection in the experimental chamber. The convection and the motor propulsion were sensitive toward molecules that inhibited the enzyme activity, thereby offering a platform for using NP-coated catalytic motors as dynamic sensing probes for harmful chemicals in liquids. Initially, effective sensing of trace amounts of Cu 2+ , Ag + , and Cd 2+ ions was performed based on the reduced propulsion of the catalytic motors through the fuel solution. The detection limit of Cu 2+ in the aqueous environment was found to be less than the permissible limit suggested by the Central Ground Water Board (CGWB), Government of India. Experiments were also conducted to demonstrate the generic applicability of motor-based detection of different enzyme inhibitors (in the micromolar concentration range), such as a flavonoid (hydroquinone) and an aromatic dipeptide (diphenylamine). Finally, it was demonstrated that the catalytic NP-coated polymer motors could also be used effectively to detect industrial effluents using samples containing different compounds that acted as enzyme inhibitors. A simple model connecting the enzyme inhibition and motor propulsion speed is presented to explain the experimental observations.

Programming Fluid Motion Using Multi-Enzyme Micropump Systems

“…[10][11][12] Other enzyme-based micropump sensors have been fabricated recently. [13][14][15][16] Distinct from prior studies on chemical pumps, we now demonstrate the assembly of multiple, distinct pumps into an interconnected active chemo-fluidic network. The multi-pump platform exploits specific connections (expressed in terms of chemistry and the produced vectorial flows) between separate pumps and thereby enables functionalities that cannot be realized within a single pump design.…”

Bacteria-derived topologies of Cu2O nanozymes exert a variable antibacterial effect

“…1–4 These synthetic nanomaterials imitate the activity of enzymes and find applications in therapeutics, 5,6 biosensors, 7–10 and for environmental remediation. 11–13 The fabrication of nanozymes 14,15 has been reported previously through various methods, 16–19 including biosynthesis, 20 electrochemical synthesis, 21 and wet chemical methods. 14,22 The rich biochemical and electrochemical capabilities of bacteria have been leveraged for fabrication of distinct morphologies of nanoparticles.…”

Detection of Single Ag–Cu2O Particle Collision and Catalysis Using Impact Electrochemistry

“…In recent years, advances in electrochemical energy at the nanoscale have been reported in the literatures. This is in line with unique attributes of nanosized materials and their impact on energy conversion and storage devices has been demonstrated. − Such materials emphasize how nanotechnology is driving innovation in these areas, leading to more efficient and sustainable energy solutions. , Micromotors/nanomotors are the miniaturized self-propelled particles, which show catalytic behavior in the presence of their respective substrates and fuel. , These particles have shown invaluable application for biosensing, − drug delivery, − and environmental monitoring − as they precisely transport therapeutic agents to specific cells or locations within the body . Their autonomous movement allows them to navigate complex environments, detecting pollutants and contaminants with remarkable accuracy.…”