Nanocarriers of Eu<sup>3+</sup> doped silica nanoparticles modified by APTES for luminescent monitoring of cloxacillin

<abstract> <p>Drug nanocarriers have been continuously improved to promote satisfactory release control. In this sense, luminescent materials have become an alternative option in clinical trials due to their ability to monitor drug delivery. Among the nanocarriers, silica stands out for structural stability, dispersibility, and surface reactivity. When using ceramic nanocarriers, one of the challenges is their interaction and selectivity capability for organic molecules, such as drugs. In order to overcome such adversity, superficial modifications can be carried out to enable a higher affinity for the desired drug. Thus, the present study aimed to obtain silica nanoparticles (NPs) doped with low concentrations of europium (III) superficially modified by (3-aminopropyl)triethoxysilane (APTES) to assess their interaction with the model drug cloxacillin benzathine. This drug was chosen because it is part of the ampicillin family and is commonly used in several treatments. Near-spherical and homogeneous silica NPs were obtained via sol-gel synthesis, with particle sizes of approximately 21 nm. It was possible to verify the fluorescence capacity of the silica NPs when doped with europium (III) in a mole percent that varied from 0.5 to 3.0%. A 10% volume percent of APTES caused the silica nanoparticles to increase the degree of hydrophobicity, with a shift in the contact angle from 8° to 51°. After surface modification by APTES, the silica nanocarrier (10 g·L^-1) achieved a satisfactory degree of CLOX incorporation (25 g·L^-1), increasing the adsorptive capacity to values above 50%. Therefore, silica NPs doped with europium (III) in a low percent of 0.5% (mole) modified by APTES showed promising results as an alternative option for trials and clinical studies of drug incorporation.</p> </abstract>