Programmable and printable formaldehyde dehydrogenase as an excellent catalyst for biodegradation of formaldehyde

As an environmental pollutant, formaldehyde can cause serious harm to the human body. Among many degradation methods, formaldehyde dehydrogenase from Pseudomonas putida (PFDH) exhibits broad potential because of its strong catalytic specificity and high degradation efficiency. However, the real application of PFDH in industry is limited by its instability and difficulties in recycling. In this work, the suitable printing conditions for immobilizing PFDH by three-dimensional (3D) printing technology were studied: the concentration of sodium alginate (SA) was 1.635 wt%, the concentration of CaCl2 was 7.4 wt%, the crosslinking time with CaCl2 was 8 min, and the temperature of the reaction was 31.5°C. 3D-printed PFDH/calcium alginate (CA) microspheres have 210% relative enzyme activity after seven repeated uses. Dried PFDH/CA particles were characterized by scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), EDS elemental mapping, and thermogravimetric analysis (TGA) which proved that the enzyme was immobilized by the material. In addition, the recycling ability of 3D printing to immobilize different objects was explored and different shapes were designed by computer-aided design (CAD). In conclusion, 3D printing technology was applied to immobilize PFDH in this work, which provides a new idea to biodegrade formaldehyde in a green way.