Biomedical applications involve the use of a huge quantity of plastics for packaging, implants, tissue engineering and drug delivery. However, there is hardly any attention paid to their sustainability and environmentally friendly properties. This group of plastics leads to a huge environmental impact.

In this work we have focused on the production and use of bacteria- derived sustainable biomaterials for use in biomedical applications. Two main types of biomaterials have been focused on, including Polyhydroxyalkanoates (PHAs) [1] and bacterial cellulose (BC) [2]. PHAs are polyesters produced by a range of bacteria including Ralstonia eutropha, Psuedomonas putida and Bacillus subtilis. These polymers are biodegradable in the soil and in the sea. In addition, they are also resorbable in the human body and are highly biocompatible. Hence the PHAs can be used for the development of green packaging materials and coatings. In addition, they can be used for direct biomedical applications such as the development of scaffolds for hard and soft tissue engineering and drug delivery. BC can also be produced by a range of bacteria including Gluconobacter xylinus and Sarcinia ventriculi. BC is also a green polymer, is sustainable and degradable in the soil. It is also highy biocompatible and can be used in biomedical applications. Polyhydroxyalkanaotes are polyesters with monomer chain length ranging between C 4 - C 16 . They are divided in to two main types, short chain length PHAs (scl- PHAs) with monomer chain length between C 4 -C 5 and medium chain length PHAs (mcl-PHAs) with monomer chain length between C 6 - C 16 .The scl-PHAs are normally hard and brittle whereas the mcl-PHAs are soft and elastomeric in nature. Hence, the scl-PHA, Poly(3- hydroxybutyrate) has been used for bone tissue engineering [3], drug delivery [4], medical devices such as coronary artery stents, and the mcl-PHAs for cardiac [5], nerve [6], pancreas, kidney and skin regeneration. For bone tissue engineering neat P(3HB) and composites of P(3HB) with Bioglass, hydroxyapatite and carbon nanotubes have been used. The mcl-PHAs have been used for the development of cardiac patches 6 , nerve guidance conduits 5 , wound healing patch, bioartificial pancreas and bioartificial kidney. Processing techniques used include additive manufacturing, electrospinning and melt electrospinning.

Bacterial cellulose has also been produced under static culture conditions using G. xylinus. This is a highly nano-fibrillated structure and hence is a great substrate for cell attachment and growth. BC has been surface modified to create antibacterial bacterial cellulose. BC has also been used as a filler for P(3HB) based composites since BC is one of the stiffest known materials. In conclusion, we have successfully used bacteria-derived sustainable biobased materials for a variety of biomedical applications and have initiated their use in environmentally friendly applications. Both PHAs and bacterial cellulose have a lot of potential in the future as sustainable materials of choice.

References

1. P. Basnett, R.K. Matharu et al. ACS Appl. Mat. Interfaces 2021 13, 28, 32624.
2. D.A. Gregory, L. Tripathi, A.T.R. Fricker, E. Asare, I. Orlando, V. Ragavendran, I. Roy Mat. Sci. Engin. 2021, 145, 100623.
3. S.K. Misra, S.P. Valappil, I. Roy, A. R Boccaccini Biomacromolecules 2006, 7, 2249.
4. R. Nigmatullin P. Thomas, B. Lukasiewicz, H. Puthussery J. Chem. Techn. Biotechn. 2015, 19, 1209.
5. A.V. Bagdadi M. Safari et al., J. Tissue Engin. Regenerative Medicine 2016.
6. L. Lizarraga-Valderrama, G. Ronchi, R. Nigmatullin, F. Fregnan, P. Basnett, A. Paxinou, S. Geuna, I. Roy Bioeng. Transl. Med. 2021, 6,3, e10223.

Acknowledgements

This work was supported by ECOFUNCO (GA number: 837863); British Council Grant-ICRG, BHF Cardiovascular Regenerative Medicine Centre, NEURIMP (Grant Agreement Number 604450), REBIOSTENT (Grant Agreement Number 604251), HyMedPoly (Grant Agreement Number 643050) and 3D BIONET.