Detecção da peçonha de Bothrops erythromelas pela interação anticorpo-antígeno em um biossensor RPS

Abstract

Snakebite accidents have a global occurrence and are considered a neglected disease. Among South American countries, Brazil has the highest rate of snakebite envenomation, predominantly caused by snakes of the Bothrops genus. The lack of rapid and reliable tests capable of accurately and quickly determining the type of snakebite envenomation is a local and global issue. Therefore, studies for the development of sensors that detect the category of snake causing the accident are crucial for safe administration of antivenom serum, considering that incorrect serotherapy can harm the patient's health. Biosensors are devices that enable detection, measurement, and amplification of signals resulting from biological interactions. Within the classes of biosensors are optical biosensors based on surface plasmon resonance, which detect changes in the refractive index near the sensing surface due to specific binding events, such as antigen-antibody interactions. This study aims to develop a simple methodology for detecting Bothrops venom by interaction with its corresponding antibodies using a highly sensitive optical biosensor; exploring the minimum venom concentration the sensor can identify, the final detection time, and the absence or presence of cross-reactivity. The assays comprise a three-layer arrangement on a sensing surface formed by a 50 nm gold film, following the order of addition: antivenom serum, crotalic venom, and finally, Bothrops venom. Different concentrations of crude venom from Bothrops and Crotalus snake genera were tested, starting from a concentration of 6,784 μg/mL until reaching the minimum concentration detected by the biosensor. The binding capacity of venom to antivenom serum (composed of IgGs) was investigated at two concentrations of antivenom serum: 5 μg/mL and 50 μg/mL. Both the antivenom serum and snake venoms were solubilized in phosphate-buffered saline (PBS). The results obtained demonstrated precise detection of the target antigen, Bothrops venom, which was tested at different concentrations. The biosensor was able to detect the venom up to a concentration of 0.848 μg/mL. Furthermore, no cross-reactivity was detected between the antibothropic serum and nonspecific venom (crotalic). Specific venom (Bothrops) detection occurred within a satisfactory time frame (up to 14 minutes). The results provide evidence that the biosensor and the methodology employed can be considered a developing diagnostic model.