The environmental toxicants such as copper are known to affect vital organ especially liver.
This study examined the effects of copper sulfate (CuSO4) on the liver morphological structure
of P. javanicus. The untreated control, 0.1 and 0.3 mg/L CuSO4 treated groups displayed normal
polygonal structure of the hepatocyte. However, at the concentrations of 0.5, 1.0 and 5.0 mg/L
CuSO4, the hepatostructure was significantly affected, as shown by the increasing number of
dilation and congestion of sinusoids, vacuolation, macrophage activities and peliosis. The
damage level and HSI value were increased while the number of hepatic nuclei per mm2 was
decreased with the increasing of copper concentration. In conclusion, this study shows that the
degree of liver damage in P.javanicus is dependent to the dose exposure.
Heavy metals with high chemical activity from sludge and waste release, agriculture, and
mining activity are a major concern. They should be carefully managed before reaching the
main water bodies. Excessive exposure to heavy metal may cause toxic effect to any types of
organism from the biomolecular to the physiological level, and ultimately cause death. Monitoring is the best technique to ensure the safety of our environment before a rehabilitation is
needed. Nowadays, enzyme-based biosensors are utilised in biomonitoring programmes as
this technique allows for a real-time detection and rapid result. It is also inexpensive and easy
to handle. Enzyme-based biosensors are an alternative for the preliminary screening of
contamination before a secondary screening is performed using high-performance technology.
This review highlights the current knowledge on enzyme-based biosensors, focusing on
cholinesterase for toxic metal detection in the environment.