Surface plasmon resonance (SPR) biosensoris a new type of high sensitivity, real-time, label-free detection technology, which plays an increasingly important role in the biomedicine field. Considering the urgent requirement of trace detection, especially for diagnosing early-stage diseases, the demand for high detection sensitivity of sensors is increasing. In recent years, various nanostructures have been proposed to design SPR biosensors. By constructing composite nanostructures, the detection sensitivity has been significantly enhanced, which has become a promising solution to expand the application of SPR biosensors. This review systematically summarized the basic principle, fabrication and illustrative application of SPR biosensors based on versatile nanostructures. Firstly, the mechanisms of various nanostructures to enhance the detection sensitivity of SPR biosensors were clarified. Then, the preparation strategies of various nanostructures were comprehensively illustrated. In addition, this review also summarized the latest applications of SPR biosensors with different structures. Finally, this review carefully highlighted the current challenges and possible development directions in future.

Refractive index (RI) and temperature (T) are both critical environmental parameters for environmental monitoring, food production, and medical testing. The paper develops a D-shaped photonic crystal fiber (PCF) sensor to measure RI and T simultaneously. Its cross-sectional structure encompasses a hexagonal-hole lattice, with one hole selectively filled with toluene for temperature sensing. By coating the D-shaped surface of the PCF with a metal film and a MoS₂ film, the refractive index-detection channel is formed. Numerical results demonstrate that RI and T can be reflected in the same spectrum, without any interference caused by the two parameters with each other. At an environmental RI of 1.26–1.38, its maximum RI sensitivity is up to 5400 nm/RIU. At a temperature of 20–80 °C, its temperature sensitivity reaches −1.2 nm/°C. This design allows for a broad operational spectrum and an extensive measurement range, which makes it particularly suitable for applications requiring low-RI detection. Moreover, the resonance strength of the sensor is significantly enhanced by introducing a two-dimensional material MoS₂ on the D-surface. Specifically, it reaches 195,149 dB/m when RI = 1.34 at 30 °C. This is much higher than that of most previous studies, and the requirements for inspection equipment can be lowered in this case. These results are essential for progress in simultaneously detecting RI and T.

Surface plasmon resonance (SPR) sensors have been widely applied in many fields because of their advantages of working in real time and high sensitivity. However, because the spectrum of an SPR sensor is easily affected by the smoothness of the metal surface, this type of sensor has obvious disadvantages in the application of quantitative detection. We designed an SPR refractive index sensor for molecular detection that has the advantage of quantifiability. A ratio spectral quantitative analysis method was established based on the two coherent dips of the SPR spectrum formed by the strong coupling effect between the surface plasmon polaritons and the excitons of the J-aggregate molecule 5,6-dichloro-2–[3–[5,6-dichloro-1-ethyl-3–(4-sulfobutyl)–2-benzimidazoline subunit] propenyl]–3-ethyl-1–(4-sulfobutyl) benzimidazole hydroxide inner salt (TDBC). The introduced MoS₂/graphene van der Waals heterojunction produced an effective charge transfer to the Ag film, resulting in significant electric field enhancement at the sensing interface and further improving the detection sensitivity of the sensor. The simulation results showed that for 43 nm Ag film, for example, the ratiometric SPR sensor with the Ag film structure can obtain 16.12 RIU⁻¹ sensing sensitivity, applied to the detection of gas molecules, while the SPR sensor with single-layer graphene and three layers of MoS₂ heterostructures can obtain 50.68 RIU⁻¹ sensing sensitivity. The addition of van der Waals heterostructures can significantly improve sensing performance by 215%.

Surface plasmon resonance (SPR) biosensors have experienced rapid development in recent years and have been widely applied in various fields. Angular-interrogation SPR biosensors play an important role in the field of biological detection due to their advantages of reliable results and high stability. However, angular-interrogation SPR biosensors also suffer from low detection sensitivity, poor real-time performance, and limited dynamic detection range, which seriously restricts their application and promotion. Therefore, we designed an angular-interrogation SPR biosensor based on black phosphorus (BP)/graphene two-dimensional (2D) van der Waals heterojunction (vdWhs). On the basis of using the angle-fixed method, this biosensor not only has good real-time performance but also detection sensitivity enhancement. The optical anisotropy characteristic of BP is used to widen the dynamic detection range of biosensors. The simulation results show that the maximum detection sensitivity of the proposed biosensor is 258.6 deg/RIU. Compared with the bare-Ag film structure biosensor, the detection sensitivity was enhanced by 209.2% by 2D vdWhs. The use of anisotropic 2D material BP can not only enhance the detection sensitivity but also widen the detection range. When the fixed incident angle is θ = 5 deg, a maximum dynamic detection range enhanced factor of 123.1% can be achieved, and a detection sensitivity of 185.2 deg/RIU in the corresponding interval can be obtained. The proposed biosensor in this study has potential broad application prospects in several fields, such as biological detection.

Surface plasmon resonance (SPR) detection technology is playing an important role in various fields such as food safety and environmental monitoring due to its excellent stability and reliability. However, there is also a growing demand for higher sensitivity in SPR sensors. Therefore, this work developed an SPR sensor based on the synergistic effect of electric-field enhancement and adsorption enhancement by using amino acid-derived carbon dots (CDs). The results showed that the incorporation of amino acid CDs can generate a maximum electric-field enhancement of up to 6.44 × 10⁵ V/m in the near-field region, which is 312% of that achieved by a bare gold film. And the adsorption kinetics results indicate that the active groups on the surface of amino acid CDs exhibit a notable adsorption enhancement effect for the target molecule (NaCl), with an adsorption capacity 335% higher than that of the bare gold film. This designed SPR sensor demonstrates a detection sensitivity of 167.28 a.u./RIU for NaCl solution, representing a 247.8% improvement compared to an SPR sensor without amino acid CDs under the same conditions. This SPR sensor shows promising potential for applications in biomedical and environmental detection fields.