## 4 Discussion
The improved thermal stability of the antibacterial green nanocomposites containing PLA, poly(butylene adipate-co-terephthalate) (PBAT) and nanocrystal cellulose (NCC)-Ag nanohybrids was also demonstrated by thermal gravimetric analysis (TGA) [36]. It was explained by the higher decomposition activation energy correlated to the AgNPs incorporation [36]. The CL runs show that the intensity of the light emission is dependent on the tested temperatures and the amount of AgNPs into bionanocomposites. The maximum in the light emissions for all bionanocomposites at 180 and 190 \({}^{\circ}\)C is reached after 100 min, since at 200 \({}^{\circ}\)C it takes about 50 min. At the same time the intensity of the bionanocomposites light emissions at 200 \({}^{\circ}\)C decreased with the increase of antimicrobial agent. It should be noted that the hydroperoxide stability is in the order: AgNPs 1.5 \(>\) AgNPs 1 \(>\) AgNPs 0.5. AgNPs could act as a nanocatalyst [43] on the PLA bionanocomposites. The results on the stability study appeared in PLA by the addition of AgNPs indicate their promising contribution to the durability of PLA based material. In the present study, the cell viability of mouse fibroblast cells cultivated in the presence of PLA bionanocomposites was investigated by quantitative MTT and LDH assays. Cell morphology was also examined after 48 h of cell incubation in the presence of the samples using hematoxylin-eosin staining. Our results indicated a high degree of biocompatibility of all tested bionanocomposites, with viability values higher than 90% after 48 h of treatment. Furthermore, a good correlation between the cell morphological observations and the quantitative results obtained by MTT and LDH viability assays was also observed. Due to their good biocompatibility, the PLA-based materials were extensively used in the field of tissue engineering. However, in order to obtain better optimized scaffolds and to increase cell proliferation and cell adhesion on their surface, PLA have been mixed with other polymers, such as collagen, gelatin or graphene oxide [44; 45]. For instance, [PERSON] et al. [45] found that PLA/collagen electrospun fibrous scaffolds at a 60:40 weight ratio showed greatest stability, cell attachment, cell proliferation, and osteogenic differentiation of bone marrow stromal cells after five-week culture period. Furthermore, hybrid fiber matrices composed of poly(d,t-lactide-co-glycolide) (PLGA), collagen, and graphene oxide were found to exhibit superior biocompatibility as well as enhanced properties for the attachment and proliferation of the C2C12 skeletal myoblasts. These matrices also induced the spontaneous myogenic differentiation, results which recommend them as potential scaffolds for skeletal muscle regeneration [46]. [PERSON] et al. [47] developed electrospun membranes based on biodegradable polylactic acid and hydrosoluble collagen for tissue engineering applications and the MTT assay used to evaluate the survival rate of L929 cells cultivated in the presence of the membranes indicated that they were suitable for the cell proliferation. In another study, poly(d,t-lactide-co-glycolide) (PLGA) nanofibrous membranes embedded with collagen were also found to be stable and biocompatible, which made them suitable to promote tendon-bone interface integration [4]. Some in vitro studies have shown that silver nanoparticles can induce toxicity at different cell levels and can cause various health problems [46; 48; 49], but used in appropriate concentrations they can be good candidates for many applications in the medical field, mainly due to their antimicrobial and anti-inflammatory properties [50]. For instance, PLA-poly(\(\epsilon\)-caprolactone) nanofibers containing lower amounts of AgNPs (0.25 wt.%) favored cell proliferation and maintained the normal cell morphology of human skin fibroblasts, suggesting them as suitable substrates for wound healing [51]. [PERSON] et al. [52] fabricated polymer composites based on PLA, hydroxyapatite and AgNPs for bone tissue engineering applications.