Evaluation of the specific migration according to EU standards of titanium from Chitosan/Metal complexes films containing TiO2 particles into different food simulants. A comparative study of the nano-sized vs micro-sized particles

Although, the current market of polymer-based food packaging that use engineered nanoparticles is increasing,
concern over toxicity due to their possible migration from polymer packaging into foodstuff affects consumer
acceptance which has been recognized as a key factor to negotiate market opportunities successfully. In this
context, the aim of this work was to evaluate the performance of films based on α-chitosan (CS)/titanium dioxide
(TiO2) nano- and micro- sized complexes in terms of (i) migration according to European Normative 1130-
1:2004, (iii) cytotoxicity and (iii) antioxidant activity by means of DPPH tests, as active films for foodstuff. To
the best of the authors’ knowledge, this is the first work assessing the migration of TiO2 from CS/TiO2 nano- and
micro- sized complexes in accordance with EU Recommendation. With regard to the specific migration tests,
which were quantified using acid digestion followed by inductively coupled plasma-mass spectrometry (ICP-MS)
detection of titanium, the results revealed that titanium can migrate from chitosan matrix after incubation in
different food simulants over 10 days at 40 ◦C or 10 days at 5 ◦C, but only in its ionic form, and no evidence of
TiO2-particle migration was found. The amount of migrated titanium was in a negligible amount (<5.44 × 10􀀀 4
% of the total titanium in the chitosan matrix), which means that under the migration test conditons used, most
of titanium is retained in the polymer matrix. The potential cytotoxicity of films’ leachates was indirectly
evaluated using two different the cell viability assays, Resazurin and CCK-8, and Caco-2 cells, from human colon
carcinoma. The results demonstrated that leachates of CS/Metal complexes films had no cell toxicity if the
samples are purified with ethanol and neutralized with 0.1 M NaOH. The resulting bio-inorganic material
exhibited a high free-radical scavenging against 1,1-Diphenyl-2-picrylhydrazyl (DPPH). The percentage inhibition
of the nano-sized CS/TiO2 complex revealed a maximum value of 41.51 % as compared to micro-sized CS/
TiO2 complex, which achieved a value of 27.13 %. This shows that chitosan complexed with nano-sized titanium
dioxide is a better radical scavenger than the chitosan complexed with micro-sized titanium dioxide, which is
explained by the lower particle size, resulting in a higher surface area.