pH-Triggered SrTiO3:Er Nanofibers with Optically Monitored and Controlled Drug Delivery Functionality

Localized drug delivery systems have long been a focus of research due to their potential for targeted treatment. While many materials have been explored, the matrix used remains a key challenge in clinical translation. Researchers have sought biocompatible and responsive materials that can adapt to physiological conditions. Strontium titanate has emerged as a promising ceramic for biomedical applications. However, its use in drug delivery systems has been limited by poor drug loading and release control. Surface modification techniques have been proposed to improve these properties. The ability to monitor drug release in real time is another unmet need in the field. Optical monitoring offers a non-invasive solution but requires integration with responsive materials. This gap motivated the development of a new system that combines pH responsiveness with optical feedback.

This study aimed to create a multifunctional drug delivery system using strontium titanate as a base material. The goal was to enhance drug loading and control release through pH responsiveness. Researchers also sought to enable optical monitoring of the drug release process. The system needed to function effectively in both neutral and acidic environments. The study focused on fabricating nanofibers doped with erbium to enable photoluminescence. The design aimed to provide real-time feedback on drug release progress. The researchers tested the nanofibers for sustained release behavior and optical response. The ultimate objective was to develop a new platform for tumor diagnosis and therapy.

The researchers used electrospinning to create fine Er-doped SrTiO3 nanofibers. The nanofibers were surface-functionalized with amino groups to improve drug loading. They tested the nanofibers in media with pH values of 7.4 and 4.7 to assess release behavior. Photoluminescence measurements were conducted using near-infrared excitation at 980 nm. The correlation between drug release and photoluminescence intensity was analyzed. The study evaluated the effect of pH on release kinetics and optical response. Researchers monitored the system's behavior in simulated physiological and acidic conditions. The mechanism of quenching by IBU molecules was investigated using vibrational frequency analysis.

The amino-functionalized nanofibers showed significantly increased drug loading capacity. In pH 7.4 media, the nanofibers exhibited sustained drug release over time. When pH was lowered to 4.7, the release rate increased substantially. The photoluminescence intensity of the nanofibers correlated with the drug release progress. Near-infrared excitation at 980 nm revealed a rapid increase in emission under acidic conditions. The quenching effect was attributed to C-Hx groups in IBU molecules. Vibrational frequencies between 2850 and 3000 cm(-1) were identified as the main contributors. The system demonstrated a clear link between pH changes and optical response.

The authors propose that the new STO:Er nanofibers offer a promising platform for localized drug delivery. The pH-triggered release mechanism aligns with the acidic tumor microenvironment. The optical monitoring capability provides real-time feedback on drug release. The system's response to pH changes supports its use in targeted therapy. The correlation between photoluminescence and drug release was confirmed experimentally. The quenching effect by IBU molecules explains the observed optical behavior. The study suggests that the nanofibers could be used in modern tumor diagnosis and treatment. The integration of pH responsiveness and optical monitoring is a novel contribution.