The need for a versatile, simple, fast and sensitive biosensor is crucial for environmental and health applications. Nowadays, enzyme-based assays in biosensing are one of the most used methods due to the high sensitivity and selectivity they present. Yet, there are some drawbacks such as instability and high cost. One strategy to overcome them is to employ the capability of metal nanoparticles deposited onto oxide nanoparticles to mimic the catalytic performance of enzymes. The immobilization of the metal nanoparticles on the oxide reduces the loss of performance related to aggregation. In addition, it produces a synergetic effect motivated by two complementary processes: a charge transfer between the materials and the creation of defects. This generates a hotspot for catalysis. We synthesized gold-coated lithium niobate nanoparticles with branched-polyethyleneimine as an intermediate linker between these two components. We showed that the intrinsic peroxidase-mimic NanoZyme activity of gold nanoparticles is upgraded when they are deposited onto lithium niobate nanoparticles. We also probed that the presence of a link between the two nanomaterials was necessary to ensure maximum efficiency. In addition, we optimized the conditions to maximize the colourimetric response (pH, temperature, quantity and surface coverage). The subsequent addition of aptamers, which bind to the gold nanoparticles, quenches the enzyme-mimics which is restored in the presence of the target. We managed to successfully attach the aptamer and the optimization of the biosensing of antibiotics is being carried out.