Development of tilapia collagen and chitosan composite hydrogels for nanobody delivery

Recently, injectable hydrogels have shown great potential in cell therapy and drug delivery. They can easily fill in any irregular-shaped defects and remain in desired positions after implantation using minimally invasive strategies. Here, we developed hydrogels prepared from tilapia skin collagen and chitosan (HCC). The residual mass rate of HCC was affected by the pH at the time of preparation, which was 29.1 % at pH 7 in 36 h. By comparison, the residual mass ratios of HCC at pH values of 6 and 5 were only approximately 8.4 % and 0, respectively. In addition, the stability of HCC was also affected by the concentration of these two components. HCC10 catalyzed by 10 mg mL^-1 tilapia skin collagen and 10 mg mL^-1 chitosan was more stable than HCC5 catalyzed by 5 mg mL^-1 tilapia skin collagen and 10 mg mL^-1 chitosan; therefore, we studied that ability of HCC10 to deliver two model nanobodies: 2D5 and KPU. As the concentration of nanobodies increased, the cumulative release rate of 2D5 decreased, and the release rate of KPU increased. Meanwhile, the cumulative release rate of 2D5 was the highest (68.3 %) at pH 5.5, followed by pH 6.8 (56.4 %) and 7.4 (28.4 %). However, the cumulative release rates of KPU were similar at pH 5.5 (45.1 %), 6.8 (46.5 %), and 7.4 (44.9 %). HCC is biodegradable, and can facilitate the release nanobodies; thus, HCC could be developed into an intelligent responsive tumor treatment matrix for use in cancer therapy.