SummaryWe investigated the structure and properties of PCL 10 nanofiber, PCL 5 /PCL 10 core-shell type nanofibers, as well as PCL 5 /PCL Ag nanofibres prepared by electrospinning. For the production of the fibre variants, a 5-10% solution of polycaprolactone (M w = 70000-90000), dissolved in a mixture of formic acid and acetic acid at a ratio of 70:30 m/m was used. In order to obtain fibres containing PCL Ag 1% of silver nanoparticles was added. The electrospin was conducted using the above-described solutions at the electrostatic field. The subsequent bio-analysis shows that synthesis of core-shell nanofibers PCL 5 /PCL 10 , and the silver-doped variant nanofiber core shell PCL 5 /PCL Ag by using organic acids as solvents is a robust technique. Such way obtained nanofibres may then be used in regenerative medicine for extracellular scaffolds: (i) for controlled bone regeneration due to the long decay time of the PCL, (ii) and as carriers of drug delivery nanocapsules. Furthermore, the used solvents are significantly less toxic than the solvents for polycaprolactone currently commonly used in electrospin, like for example chloroform (CHCl 3 ), methanol (CH 3 OH), dimethylformamide (C 3 H 7 NO) or tetrahyfrofurna (C 4 H 8 O), hence the presented here electrospin technique may allow for the production of multilayer nanofibres more suitable for the use in medical field.