No abstract

We developed a simple impedimet ric biosensor for the detection of bacterial lipopolysaccharide (LPS) based on lectin-functionalized gold nanoparticle (AuNP)-graphene (G) composites. The effects of AuNPs on G were investigated by comparison with the sensing surface in the absence of AuNPs. The results showed that the AuNPs formed a 3D micro/ nanocomposite on G, which increased the electroactive area from 7.03 × 10 −2 to 1.41 × 10 −1 cm 2 , and also increased the heterogeneous electron transfer rate, which can improve the sensitivity of the biosensor. Concanavalin A (Con A) lectin was used as a molecular recognition element because of its specific interaction toward the carbohydrate groups in LPS. The increase in electron transfer resistance was in a logarithmically direct proportion to the LPS concentration and lowered the detection limit to 600 pg/L. The fabricated biosensor achieved the detection of LPS with good sensitivity, acceptable reproducibility, and stability. This method may hold promise for potential applications in glycomic biosensing.

The long-term large-scale planting of genetically modified (GM) crops may have potential impacts on the health and stability of agricultural ecosystems while benefitting agricultural production. Bt proteins expressed in Bt crops have a good control on target pests. However, non-target insects that are not susceptible to Bt toxins may have increased populations rapidly, causing significant damage to crops. With the long-term continued cultivation of insect-resistant GM crops, different reports and views on the amounts of pesticide applications have been reported. Based on existing research, we reviewed the characteristics and status of non-target insect pest outbreaks and analyzed the main causes of the outbreaks (such as insecticide use, decrease of natural enemies, and species replacement). In addition, we discussed the effects of GM crops on non-target pests over long-term cultivation using Bt corn and cotton as examples. Given the existing problems of non-target insect outbreaks due to commercial applications of Bt crops, further studies on monitoring the efficacies of insect-resistant GM crops are necessary to prevent outbreaks of non-target pests needed for sustainable agriculture.