Dengue viral infection is one of the most common deadliest diseases and has become a recurrent issue for public health in tropical countries. Although the spectrum of clinical diagnosis and treatment have recently been established, the efficient and rapid detection of dengue virus (DENV) during viremia and the early febrile phase is still a great challenge. In this study, a dithiobis (succinimidyl undecanoate, DSU)/amine-functionalized reduced graphene oxide-–polyamidoamine dendrimer (DSU/amine-functionalized rGO–PAMAM) thin film-based surface plasmon resonance (SPR) sensor was developed for the detection of DENV 2 E-proteins. Different concentrations of DENV 2 E-proteins were successfully tested by the developed SPR sensor-based system. The performance of the developed sensor showed increased shift in the SPR angle, narrow full-width–half-maximum of the SPR curve, high detection accuracy, excellent figure of merit and signal-to-noise ratio, good sensitivity values in the range of 0.08–0.5 pM (S = 0.2576°/pM, R² = 0.92), and a high equilibrium association constant (K_A) of 7.6452 TM⁻¹. The developed sensor also showed a sensitive and selective response towards DENV 2 E-proteins compared to DENV 1 E-proteins and ZIKV (Zika virus) E-proteins. Overall, it was concluded that the Au/DSU/amine-functionalized rGO–PAMAM thin film-based SPR sensor has potential to serve as a rapid clinical diagnostic tool for DENV infection.

We report the use of a biofunctionalized tapered optical fiber based sensor with the integration of graphene oxide (GO) for the detection of Dengue virus (DENV) II E proteins. The tapered region was deposited with GO and functionalized with anti-DENV II E protein IgG antibodies to be tested with different concentrations of DENV II E proteins. The sensor obtained a detection limit of 1 pM with a sensitivity value of 12.77 nm/nM, which was better compared to previously reported studies. The sensor also showed high precision, great selectivity, and high affinity toward E protein with a dissociation constant of K _d = 1.11 × 10 ^-9 M ^-1 . The proposed sensor has undoubtedly exhibited the immense potential of nanomaterial integration for future advancements of dengue diagnostics.

Ammonia detection in ambient air is critical, given its implication on the environment and human health. In this work, an optical fiber tapered to a 20 µm diameter and coated with graphene oxide was developed for absorbance response monitoring of ammonia at visible (500–700 nm) and near-infrared wavelength regions (700–900 nm). The morphology, surface characteristics, and chemical composition of the graphene oxide samples were confirmed by a field emission scanning electron microscope, an atomic force microscope, X-ray diffraction, and an energy dispersion X-ray. The sensing performance of the graphene oxide-coated optical microfiber sensor towards ammonia at room temperature revealed better absorbance response at the near-infrared wavelength region compared to the visible region. The sensitivity, response and recovery times at the near-infrared wavelength region were 61.78 AU/%, 385 s, and 288 s, respectively. The sensitivity, response and recovery times at the visible wavelength region were 26.99 AU/%, 497 s, and 192 s, respectively. The selectivity of the sensor towards ammonia was affirmed with no response towards other gases.

A prism-based surface plasmon resonance (SPR) sensor deposited with reduced graphene oxide/maghemite is presented for the detection of lead ions (Pb ²⁺ ) in water. The SPR setup proposed followed the Kretschmann configuration with the installment of the nanocomposite integrated bilayer sensor chip onto the prism. For protection, the nanocomposite active layer was coated with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimidehydrochloride/N-hydroxysuccinimide. When the sensor was tested with different concentrations of Pb ²⁺ in static water, the limit of detection was achieved at 0.001 ppm with a resonance angle shift of 0.184°. As an improvisation, a sample circulation design was adapted into the setup in order to increase the interaction rate between the sample and the sensing layer. This managed to improve the detection limit to 0.3 ppb.

Biosensors are central to diagnostic and medicinal applications, especially in terms of monitoring, managing illness, and public health. Microfiber-based biosensors are known to be capable of measuring both the presence and behavior of biological molecules in a highly sensitive manner. In addition, the flexibility of microfiber in supporting a variety of sensing layer designs and the integration of nanomaterials with biorecognition molecules brings immense opportunity for specificity enhancement. This review paper aims to discuss and explore different microfiber configurations by highlighting their fundamental concepts, fabrication processes, and performance as biosensors.