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- A bi-layer electrospun nanofiber membrane for plasmid DNA recovery from fermentation brothsPublication . Correia, Tiago R.; Antunes, Bernardo Paiva; Castilho, Pedro Henrique Barata; Nunes, José; Amorim, Maria T. Pessoa de; Escobar, Isabel; Queiroz, João; Correia, I.J.; Morão, AntónioThe demanding ever-increasing quantities of highly purified biomolecules by bio-industries, has triggered the development of new, more efficient, purification techniques. The application of membrane-based technologies has become very attractive in this field, for their high throughput capability, simplicity of operation and scale-up. Herein we report the production of a bi-layer membrane by electrospinning (ES), in which a support of poly ε-caprolactone nanofibers was coated with a polyethylene oxide/sodium alginate layer, and subsequently cross-linked with calcium chloride. The membranes were characterized by SEM, ATR-FTIR, contact angle measurements, and were applied in the recovery process of a plasmid. The results show that membranes retained the suspended solids while allowing the permeation of plasmid DNA, with high recovery yields and improved RNA retention. Moreover, they also showed a very low fouling tendency. To the best of our knowledge it is the first time that ES membranes are applied in this type of bioprocess.
- Effect of Polymer Dissolution Temperature and Conditioning Time on the Morphological and Physicochemical Characteristics of Poly(Vinylidene Fluoride) Membranes Prepared by Non-Solvent Induced Phase SeparationPublication . Cardoso, V. F.; Botelho, Gabriela; Morão, António; Nunes-Pereira, J.; Lanceros-Mendez, SenentxuThis work reports on the production of poly(vinylidene fluoride) (PVDF) membranes by non-solvent induced phase separation (NIPS) using N,N-dimethylformamide (DMF) as solvent and water as non-solvent. The influence of the processing conditions in the morphology, surface characteristics, structure, thermal and mechanical properties were evaluated for polymer dissolution temperatures between 25 and 150 C and conditioning time between 0 and 10 min. Finger-like pore morphology was obtained for all membranes and increasing the polymer dissolution temperature led to an increase in the average pore size ( 0.9 and 2.1 m), porosity ( 50 to 90%) and water contact angle (up to 80 ), in turn decreasing the PVDF content ( 67 to 20%) with the degree of crystallinity remaining approximately constant ( 56%). The conditioning time did not significantly affect the polymer properties studied. Thus, the control of NIPS parameters proved to be suitable for tailoring PVDF membrane properties.
- Modification of microfiltration membranes by hydrogel impregnation for pDNA purificationPublication . Castilho, Pedro Henrique Barata; Correia, Tiago R.; Amorim, Maria T. Pessoa de; Escobar, Isabel; Queiroz, João; Correia, Ilídio Joaquim Sobreira; Morão, AntónioThe huge efforts for the achievement of highly purified biomolecules are growing every day. A great number of efficient techniques, such as chromatography, are already available in laboratory for separation processes. However, membrane‐based technologies are the best match to assure simplicity, efficiency and easy scale‐up procedures. Herein we report the modification of a commercial microfiltration membrane for plasmid DNA purification by agarose gel impregnation. The membrane was characterized by SEM, ATR‐FTIR, EDS, contact angle, and porosity measurements. Additionally, the membrane pore radius was estimated from observed rejections of different proteins and with that information the rejection of a 6050 bp plasmid DNA (pDNA) molecule was estimated for different values of flux using a theoretical model of large flexible molecules in membranes with parallel cylindrical pores, which is applicable to pDNA ultrafiltration in conventional membranes, as recently shown in the literature. The experimental results show that the modified membrane has higher pDNA rejections than the predicted by the model, suggesting that the different type of porous structure that a hydrogel has, may have a positive effect on pDNA rejections as compared to other biomolecules with more rigid structures, making this type of modified membranes potential better candidates to be used for the selective recovery of pDNA in this type of bioprocesses.