Stastistical optimization of biofunctionalization condition of native spider web from Crossopriza lyoni

Abstract

Spider silk has been known as a promising biomaterial to be applied in various fields. With its outstanding characteristics, exploiting this organic material can bring a lot of benefits to mankind. Natural spider silks do not exhibit functional properties thus; many researchers attempted the induction on synthetic spider threads. Nevertheless, only few studies were reported on the functionalization of naturally occurring spider silk fibers. The aim of this research was to functionalize Crossopriza lyoni spider silk web by graphite coating for conductivity induction. In the method development for graphite attachment, sodium dodecyl sulfate (SDS) was used to enhance the coating efficiency of graphite molecules onto the surface of the fiber. Screening of parameters for significant coating conditions such as temperature, concentration of graphite solution, and incubation time were performed. The significant parameters were further optimized by Response Surface Methodology (RSM) via Box-Behnken Design (BBD) for optimal coating condition. The coating method was successfully achieved by applying the use of surfactants, making the graphite molecules more capable of diffusing onto the surface of spider silk fiber. Respective parameters exerted significant effect on graphite coating of spider silk fibers at p < 0.001. In addition, it is inferred that the graphite coating condition on spider silk fiber tends to produce maximal conductivity at low temperature, high graphite concentration and low incubation time. Following the optimization using BBD, graphite-coated spider silk fibers were induced with the highest conductivity value (3.62 S/m) at 25 ºC, 2.43 % graphite concentration for 4.5 hours with fitted model of p < 0.0001. The determination of an optimum graphite coating on spider silk fiber condition was essential to provide a basis for scaling-up in the future. Future applications on using this spider silk fiber may be on developing wires or applied as a material to make good conductors. The idea of inducing graphite on spider silk fiber will indeed widen up the range of exploiting applications of the respective organic material.