Yiyan Xie

Cronobacter sakazakii (C. sakazakii) is a food pathogen that has drawn attention in the area of food safety, especially in relation to infant formula and other food matrices. However, the typical methods for detecting C. sakazakii can be tedious, time-consuming, and need complex tools and equipment, which restricts their use for quick detection. As a result, sensitive and quick detection techniques are essential. In the present study, a new type of optical fiber biosensor was developed, which combines CeCoMOF@Ag@MoS₂ nanomaterials and gold nanorods (AuNRs). The sensor adopts a multimode fiber (MMF)–lanthanum-doped fiber (LDF)–MMF (MLM) fiber structure, and the integration of CeCoMOF, Ag@MoS₂, and AuNRs combines the structural advantages of the porous framework with the plasmonic response of the metallic nanostructures, providing a composite sensing interface for optical fiber LSPR detection and measuring the refractive-index sensitivity of different concentrations of C. sakazakii. The sensing interface was designed by integrating CeCoMOF@Ag@MoS₂ and AuNRs on the probe surface to optimize the LSPR response and provide a suitable platform for antibody functionalization. The probe was subsequently functionalized with monoclonal antibodies against C. sakazakii to facilitate target recognition. According to the experimental findings, the developed sensor’s detection range is 1 × 10⁰–1 × 10⁷ CFU/mL, the sensitivity is 5.1447 nm/[CFU/mL], and the detection limit is 0.78 CFU/mL. Moreover, the sensor has good repeatability, stability, selectivity, and reusability. The performance of the suggested sensor was analyzed in terms of sensing capabilities with starch-based matrix under the conditions tested. Note that the enhanced performance is not just due to La doping but due to the combined effect of the multi-tapered MLM structure, La doping and the nanomaterial–antibody interaction.

The incorporation of hybrid nanomaterials and fiber architectures into fiber-optic biosensors has proven to be effective in improving sensing performance. This study developed a plasmonic biosensor using a tapered multimode fiber (MMF)–multicore fiber (MCF)–MMF structure functionalized with a nanocomposite of gold nanoparticles (AuNPs), tungsten disulfide quantum dots (WS₂-QDs), and multi-walled carbon nanotubes (MWCNTs) for selective triclosan detection. Combining WS₂-QDs and MWCNTs with AuNPs leverages their individual advantages, creating an active sensing interface with abundant analyte-binding sites, thereby substantially improving responsiveness. The composite-modified structure also promotes higher-order mode generation, which is critical for sensitivity enhancement. When optically excited, the periodic plasmonic geometry produces strong evanescent fields that intensify interactions between the immobilized nanocomposite and target molecules. Transmission spectroscopy demonstrated that the biosensor achieved a detection limit of 3.87 µM within the 0–40 µM range. These results show that the strategic combination of WS₂-QDs and MWCNTs with AuNPs significantly amplifies localized surface plasmon resonance (LSPR) effects. This architecture offers a promising approach for developing sensitive fiber-optic biosensors, particularly for environmental monitoring of agents like triclosan.

Gentamicin is an important pollutant in milk that causes harm to the human body. In this study, a plasmonic biosensor with a tapered multi-mode fiber (MMF) and four-core fiber (FCF) and multi-mode fiber (MMF) structure was developed. Localized surface plasmon resonance (LSPR) was stimulated by immobilizing gold nanoparticles (AuNPs) on the optical fiber probe surface. Cubic silver oxide (Ag ₂ O) was used to modify the fiber-optic probe by altering the dielectric environment around the AuNPs, which modulated the LSPR phenomenon, expanded the probe surface area, and enlarged the adhesion zone for gentamicin monoclonal antibodies, thereby enhancing the selectivity of the sensor. Transmittance experiments showed the sensor had a linear range of 15-55 nM, LoD = 5.84 nM. Tests on repeatability, stability, pH and selectivity confirmed its reliable performance; the results of these experiments demonstrate strong potential for practical food safety applications in detecting gentamicin levels in food.

Acrylamide (AA), a harmful aliphatic amide, is produced during the thermal processing of food as a result of the Maillard reaction between asparagine and reducing sugars. It has neurotoxic effects and can cause cognitive impairment with long-term exposure. Moreover, chronic intake of AA may increase the risk of various types of cancer, including pancreatic and thyroid cancer. AA is often found in foods cooked at high temperatures, thereby highlighting its role in food quality assessment. Therefore, there is a need for more accurate, practical, rapid, and straightforward methods to detect AA in various samples. In this study, a highly sensitive and selective smart fiber-optic WaveFlex biosensing method based on localized surface plasmon resonance (LSPR) is proposed for the detection of AA. The fiber surface is functionalized with gold nanoparticles (AuNPs), multi-walled carbon nanotubes (MWCNTs) and zinc oxide nanowires (ZnO-NWs) to provide a larger surface area for the immobilization of AA antibodies, which in turn significantly improved the sensor's performance. The results showed that the developed sensor could efficiently detect AA with high specificity due to the presence of AA antibodies. Subsequent research confirmed that the proposed biosensor exhibited excellent stability, repeatability, and reusability, with a limit of detection (LOD) of 0.438 μg/mL and a sensitivity of 0.685 nm/(μg/mL). Thus, the proposed optical fiber sensor holds significant potential for detecting the presence of AA in various deep-fried foods prepared at high temperatures.

Acrylamide (AA), a detrimental aliphatic amide, is generated during food thermal processing as a result of the Maillard reaction occurring between asparagine and reducing sugars. WaveFlex fiber is a fiber-optic flexible sensor designed to enhance the evanescent wave for effectively exciting the localized surface plasmon resonance (LSPR) phenomenon, and in this study, the authors use this type of sensor to detect varying levels of AA. By immobilizing gold nanoparticles (AuNPs) on the probe’s surface, the evanescent field has the capability to trigger the activation of AuNPs and induce the occurrence of LSPR phenomena. In order to excite LSPR better and generate stronger evanescent field, WaveFlex biosensor is fabricated using single-mode fiber. Cerium oxide nanorods (CeO ₂ -NRs) and MXene are used to modulate the LSPR phenomenon by altering the dielectric environment of AuNPs. As a result, the sensing performance of the sensor is improved and the surface area of the fiber probe is increased, providing an additional attachment point for the AA antibody. The AA sensor’s specific selectivity is enhanced by functionalizing the surface of the sensing probe with acrylamide antibody. The sensor has a linear range of 3 to 13 μg/mL with a detection limit of 1.13 μg/mL. Finally, the recoveries of AA in biscuits and chips are 82.8% ~ 99.7% and 83.7% ~ 100.4%, respectively. Furthermore, the probe’s potential for detecting AA levels is demonstrated through rigorous testing of its reusability, reproducibility, stability, pH, and selectivity. The obtained results indicate a promising application scope for this WaveFlex biosensor.

Infections caused by Vibrio parahaemolyticus (V. parahaemolyticus) can be highly fatal, making rapid and sensitive detection of them is essential. A new optical fiber biosensor based on localized surface plasmon resonance (LSPR) phenomenon is developed in this paper. A tapered-in-tapered fiber structure based on MFM is constructed by using four-core fiber (FCF) and multi-mode fiber (MMF) to qualitatively detect different concentrations of V. parahaemolyticus. The sensor successfully excites the LSPR phenomenon and increases the attachment point of biomolecules on the probe surface by fixing gold nanoparticles (AuNPs), molybdenum disulfide nanoparticles (MoS₂-NPs) and cerium dioxide nanorods (CeO₂-NRs). The functionalization of polyclonal antibodies on the probe surface can improve the specificity of the sensor. The linear detection range of the developed sensor was 1 × 10⁰-1 × 10⁷ CFU/mL, the sensitivity was 1.61 nm/[CFU/mL], and the detection limit was 0.14 CFU/mL. In addition, the reusability, reproducibility, stability, and selectivity of the sensor probe are also tested, which shows that the sensor has great application prospects.