Designing biocarriers is an effective approach for preserving bioactive components in challenging conditions and ensuring their controlled release in targeted environments, thereby enhancing their efficacy. Bacterial polymers, noted for their beneficial properties, create robust and stable structures and are among the most commonly used sources for developing innovative materials. This research focuses on creating particles derived from bacterial cellulose (BC) and biobased polyhydroxybutyrate (PHB) to serve as bionanocarriers. BC, a hydrophilic and porous biopolymer, is known for its high-water retention and tensile strength, whereas PHB, a hydrophobic polymer, provides excellent barrier properties and UV resistance. This study aims to develop a biodegradable PHB coating on BC microparticles to regulate bacterial release. A primary challenge is ensuring the compatibility of both polymers in a stable system . To address this, we covalently bonded the two polymers to form the core particle (BC-PHB). We then utilized a one-step coaxial electrospray technique to prepare unique spherical double-shell hollow particles (DSHP). These DSHP feature a PHB outer shell and a BC-PHB inner shell with a hollow core capable of encapsulating live bacterial cells. The resulting DSHP are stable, spherical microparticles with a PHB outer surface and a BC-PHB inner layer that can house living cells. The inner cavity can hold bacteria at concentrations up to 1.4 ×108 CFU/mL, while the thin outer PHB layer serves as a protective barrier, ensuring the stability and controlled,sustained release of the enclosed live cargo. Due to the biodegradability and low toxicity of the components, BC-PHB DSHP show promise for applications in biomedical or environmental fields.

This work received financial support from the Spanish Ministry of Science and Innovation under the research grant BIOCIR (PID2020–112766RB-C21), funded by MCIN/AEI/10.13039/501100011033/ and from the Community of Madrid [P2018/NMT4389].

Peer reviewed

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