## 3 Results and Discussion
This feature may be the signature of an inductive behaviour where energy is stored as a magnetic field, albeit it is our opinion that this is unreasonable due to the excessive and incredibly large corresponding inductance. On the other hand, assigning the low-frequency hook to a negative capacitance is even more unrealistic. Figure 4: Impedance analysis of pristine porous HCPEG monolithic specimens (**a,b**) and porous HCPEG monolithic loaded with: GNWs (0.4% wt). (**c,d**), PANI (0.8% wt) (**e,f**) and PANI (0.8% wt) + GNWs (0.4% wt) (**g,h**). More reasonably, the low-frequency hook comes from the entanglement or reciprocal interaction between the PANI, which is dispersed in the polymer matrix, and the porosity, which is partially filled with GNWs. AC conductivities of these composites were obtained from the dielectric losses measured as a function of pulsation [50] according to Equation (3):  
\[\sigma_{AC}(\omega)=\varepsilon_{0}\omega\epsilon^{\prime\prime} \tag{3}\]  
Then the DC conductivities (Figure 5) were obtained by applying Jonscher's power law [51] in Equation (4):  
\[\sigma_{AC}(\omega)=\sigma_{DC}+K\omega^{s} \tag{4}\]  
For the production of mixed matrices, i.e., containing both fillers, it was decided to use GNW at the highest concentration (0.4% wt) for each specimen as it offers the best results in terms of porosity, and to vary only the contents of PANI. As expected electrical and dielectric properties are strongly influenced by the addition of fillers. PEG porous matrix exhibited a typical insulating behavior characterized by low DC conductivity. By adding PANI, a semiconductive polymer, the DC conductivity increased as the filler content was increased, and a further increase occurs when GNWs are also present. The processability of the porous plastic material was tested against several runs of microneedles arrays replica molding (Figure 6). SEM morphological analysis shows that the material well replicates an array of microneedles by following this simple procedure. It is worth it to note that the internal porous architecture is preserved in the microneedles (Figure 6) despite the replica process. As pointed out previously, water solutions can penetrate throughout the polymer matrix and enter the pores. These pores can act as micro/nano-flasks hosting molecules or even nanostructures. The inclusion of nanostructures represents a surplus due to the following reasons: (i) they can be firmly anchored to the pores due to their size, making impossible for them to escape into the matrix; (ii) nanostructures, can be imparted with specific functionalities to open up a wide range of applications. Figure 5: DC conductivity of the composite materials with inner porous structure. Overall, the pores can behave as micro/nano-reactors with a relevant chemical entity, such as a catalyst, firmly anchored inside and the proper reactant molecules can reach the pores through the polymer mesh by diffusion, feeding in this way the reaction. To test this hypothesis, we made a preliminary experiment by loading free glucose oxidase enzyme, GOX (Figure 7a,b), enzymatic activity was tested by colorimetric assay [52]. Remarkably, the monolithic porous material loaded with GOX (1 U/mL) and PANI (0.8% wt) retained the enzymatic activity towards glucose oxidation to glucanolactone (Figure 7c). Some decrease of the GOX enzymatic activity was observed likely due to a partial denaturation of the enzyme occurring during the monolith fabrication process. The colorimetric marker quinoneimine was generated by the reaction catalyzed by horseradish peroxidase (HRP) which uses the hydrogen peroxide generated and released by the pores because of the glucose oxidase (GOX) enzymatic reaction (see section Enzymatic activity analysis). Ultimately, the marker is only detected when hydrogen peroxide starts leaving the specimen to reach the solution. Accordingly, when the reaction is carried out in the pores we observed a longer induction period (Figure 7c).