Silver nanoparticles (AgNPs) have attracted tremendous attention in recent years due to their unique physicochemical properties, including pronounced surface plasmon resonance, tunable size, and amenability to functionalization. These attributes underpin the growing interest in AgNPs as SMART nanocarriers for targeted drug delivery and as active components in biosensing platforms. In this work, we discuss various synthesis strategies for AgNPs—ranging from conventional chemical methods to green approaches—and highlight their subsequent functionalization with anticancer drugs, notably doxorubicin (DOX). We also examine the potential of AgNPs in biosensor applications, emphasizing electrochemical and optical detection modalities capable of monitoring drug release, oxidative stress, and relevant biomarkers. Our experimental data support the conclusion that AgNPs can effectively improve therapeutic efficacy by exploiting tumor-specific conditions (e.g., lower pH) while also enhancing biosensor sensitivity via surface plasmon resonance and electrochemical signal amplification. We provide a thorough discussion of the results, including mechanistic aspects of reactive oxygen species (ROS) generation, drug release kinetics, and sensor performance metrics. Overall, AgNP-based nanocarriers emerge as a powerful platform to address current challenges in precision oncology and medical diagnostics.

The rapid and accurate detection of SARS-CoV-2, particularly its spike receptor-binding domain (S-RBD), was crucial for managing the COVID-19 pandemic. This study presents the development and optimization of two types of aptasensors: quartz crystal microbalance (QCM) and electrochemical sensors, both employing thiol-modified DNA aptamers for S-RBD detection. The QCM aptasensor demonstrated exceptional sensitivity, achieved by optimizing aptamer concentration, buffer composition, and pre-treatment conditions, with a limit of detection (LOD) of 0.07 pg/mL and a linear range from 1 pg/mL to 0.1 µg/mL, and a significant frequency change was observed upon target binding. The electrochemical aptasensor, designed for rapid and efficient preparation, utilized a one-step modification process that reduced the preparation time to 2 h while maintaining high sensitivity and specificity. Electrochemical impedance spectroscopy (EIS) enabled the detection of S-RBD concentrations as low as 132 ng/mL. Both sensors exhibited high specificity, with negligible non-specific interactions observed in the presence of competing proteins. Additionally, the QCM aptasensor’s functionality and stability were verified in biological fluids, indicating its potential for real-world applications. This study highlights the comparative advantages of QCM and electrochemical aptasensors in terms of preparation time, sensitivity, and specificity, offering valuable insights for the development of rapid, sensitive, and specific diagnostic tools for the detection of SARS-CoV-2 and other viruses.