In the last few decades, plasmonic colorimetric biosensors raised increasing interest in bioanalytics thanks to their cost-effectiveness, responsiveness, and simplicity as compared to conventional laboratory techniques. Potential high-throughput screening and easy-to-use assay procedures make them also suitable for realizing point of care devices. Nevertheless, several challenges such as fabrication complexity, laborious biofunctionalization, and poor sensitivity compromise their technological transfer from research laboratories to industry and, hence, still hamper their adoption on large-scale. However, newly-developing plasmonic colorimetric biosensors boast impressive sensing performance in terms of sensitivity, dynamic range, limit of detection, reliability, and specificity thereby continuously encouraging further researches. In this review, recently reported plasmonic colorimetric biosensors are discussed with a focus on the following categories: (i) on-platform-based (localized surface plasmon resonance, coupled plasmon resonance and surface lattice resonance); (ii) colloid aggregation-based (label-based and label free); (iii) colloid non-aggregation-based (nanozyme, etching-based and growth-based).

Candida albicans is a fungal organism commonly found in the human body, including the genitourinary tract.

Direct electrostatic self-assembly of cationic AuNPs on glass delivers ultra-uniform, high-density metasurfaces via solvent exchange and fast drying. When particle size is optimal, far-field coupling emerges, boosting plasmonic Q -factors up to ∼15.

Prostate cancer stands as the second most frequent form of cancer found in men. Early and accurate disease diagnosis is crucial, particularly during the initial stages when prostate-specific antigen (PSA) biomarkers are present in low concentrations. Addressing the imperative for efficient detection methods, metal-enhanced fluorescence (MEF)-based biosensors are emerging as exceptional candidates due to their unmatched sensitivity and precision. In this letter, an MEF-based immunosensor integrated with a customized fluidic setup has been developed. The biosensor consists of gold nanoparticles (AuNPs) randomly immobilized onto a glass substrate via an electrostatic self-assembly technique. A sandwich scheme has been employed for PSA recognition, with antibodies as capture bioreceptor covalently immobilized onto the AuNPs surface and a top fluorescently labeled bioreceptor layer. The customized fluidic system ensures a high surface coverage that significantly amplifies the antibody–analyte bindings compared to diffusion. The biosensor has been tested on real samples, successfully detecting PSA in human serum within a rapid 40-min assay time by reaching a limit of detection (LOD) of 150 pg·mL ⁻¹ .

The sensitive and rapid detection of low-concentration DNA sequences in complex biological matrices remains a critical need across biomedical, environmental, and food sectors. While amplification-based techniques like PCR offer high sensitivity, they are constrained by the need for complex instrumentation and skilled personnel, limiting their use in decentralized settings. Electrochemical biosensors are attractive for point-of-care testing due to their speed and portability, but are hindered by probe immobilization variability, sample interference, and labeling requirements. There is a clear need for robust, label-free, and easy-to-use DNA biosensors capable of performing reliably in real-world complex matrices. We present a label-free impedimetric DNA biosensor integrating screen-printed gold electrodes (AuSPEs) with an optimized 3D-printed fluidic cell. This innovative design ensures consistent probe immobilization while significantly improving hybridization efficiency through controlled convective transport, as demonstrated by COMSOL simulations. The platform achieves sensitive detection with a LOD of 0.1 pM (0.6 pg/mL) in PBS buffer using electrochemical impedance spectroscopy (EIS), eliminating requirements for target amplification or extensive sample preparation. The biosensor maintains excellent performance in complex biological media, successfully detecting target sequences in untreated S. cerevisiae culture supernatants with minimal matrix interference. Furthermore, the system demonstrates exceptional discrimination capability, reliably identifying single-base mismatches while exhibiting minimal cross-reactivity with supernatants from non-target microorganisms (E. coli and C. albicans). These results highlight the system's sensitivity, selectivity, and robustness for nucleic acid detection. This study represents a notable advancement in electrochemical biosensing, introducing a modular, amplification-free platform capable of highly sensitive DNA detection in both buffer solutions and complex biological samples. Its low cost, operational simplicity, and reliable performance in real-world matrices make it a promising candidate for point-of-care applications. This approach offers a practical alternative for molecular diagnostics and monitoring in clinical, environmental, and industrial contexts.