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This study aims to encapsulate the fungicide carbendazim using a biodegradable polymer (pectin). First, we have obtained calcium pectinate beads (CPG-Carb) by ionotropic gelation using calcium ions as a crosslinking agent. These beads were then coated with silica starting from tetraethoxysilane (TEOS), by a sol-gel process to form hybrid beads (CPG-Carb-SG). The morphology, composition and structure of both beads were characterized and the controlled release assays of the fungicide were studied in both water and soil columns. The encapsulation efficiency for CPG-Carb was slightly higher (75%) compared to CPG-Carb-SG (67%) due to carbendazim loss during the impregnation and condensation steps. The release rate in water and soil columns was about 4 times lower for CPG-Carb-SG than CPG-Carb demonstrating the efficiency of the silica coating to delay the release of carbendazim. Moreover, the release of CPG-Carb-SG is due to the erosion of the silica layer during the first two weeks. After this period, the silica layer was degraded, and the release is then controlled by the swelling of the organic part of the bead as observed for CPG-Carb. Finally, the biodegradability of the pectin, and the release profile make such systems promising candidates for sustained and economical pesticide delivery systems.

Congenital hypothyroidism (CH) is one of the most common preventable causes of mental retardation. The majority of infants are diagnosed after detection through newborn screening programs using thyroid-stimulating hormone (TSH) test. A rapid immunochromatographic lateral flow assay based on monoclonal antibodies (MAbs) colloidal gold nanoparticles was developed in a sandwich format for the detection of TSH. Two MAbs binding distinct TSH epitopes are used; one is conjugated to the detection reagent while the other is immobilized at the test line on the membrane. The colloidal gold was prepared by the reduction of gold salt coupled with MAbs and this optimal concentration was determined by spectrophotometry method. The sensitivity of our developed lateral flow immunoassay was determined using 5, 10, 15, 25 and 50 μUI/mL of TSH. The color intensity of the test line was directly proportional to the TSH concentration and the visual limit of detection was 10 μUI/mL. Twenty samples of umbilical cord serum were analyzed by the developed strips and the intensity of the signal was in agreement with the results obtained by the conventional radioimmunoassay method. The results suggest that this rapid test can be used in initial screening for congenital hypothyroidism especially in rural areas.