Regenerative medicine and tissue engineering may offer new hope of life in case of loss or malfunction of a tissue or organs. One of the key elements in tissue engineering is the three-dimensional (3D) scaffold which provides structural support for cell attachment, proliferation and differentiation. Biopolymer scaffolds are preferred in tissue engineering for avoiding the issues related to donor immune rejection and pathogen transfer. Cellulose, the most abundant natural polymer on earth, is an almost inexhaustible source of valuable materials and has gained high interest in the form of nanocellulose (NC). NC stands out for its high crystallinity and mechanical strength, good biocompatibility, high water-holding capacity and large surface area and it has been intensively studied for medical applications because it does not cause toxic or allergic side effects in contact with living tissue. 3D scaffolds should possess a network of interconnected pores to permit cell migration, diffusion of nutrients and clearance of wastes, they must be able to support cell adhesion and promote cell growth and they must have balanced stiffness-toughness properties to support and transfer of loads. To meet all these requirements in porous 3D scaffolding, CELL-3D has as main objective to design new 3D nanocellulose structures that can be applied in regenerative medicine.
In the first phase, porous nanocellulose structures have been obtained from three different sources of nanocellulose, namely a nanocellulose obtained from the mechanical disintegration of bacterial cellulose membranes, a nanocellulose obtained by acid hydrolysis of microcrystalline cellulose and a nanocellulose obtained from agricultural residues. Nanodimension of the samples was highlighted by AFM, SEM and TEM. In order to obtain the porous structures, nanocellulose samples were functionalized by silanes and crosslinked using non-toxic crosslinking agents with different efficiency. In another approach, ionic agents have been used to obtain hydrogels and cryogels of nanocellulose. These methods led to controlled 3D structures with interconnected micro- and nano-pores. Porous 3D structures were characterized to emphasize changes in morphology, structure, thermal and mechanical properties and to detect the influence of the treatments (functionalization and crosslinking) on these characteristics. The methodology to obtain functionalized nanocellulose was elaborated. Moreover, the scientific report on the correlation between the process parameters, composition and the thermal and mechanical properties as well as morphology of 3D functionalized nanocellulose structures was released.
In the second phase, new functionalization-crosslinking methods of bacterial cellulose nanofibers were developed and their efficiency was evaluated based on the thoroughly characterization of the thermal and mechanical properties as well as morphological features of the obtained 3D cellulose structures. A three-level organization in the 3D structures was detected by SEM investigation. A 5-fold increase in the specific compression and a minor decrease in thermal stability were observed depending on the reaction conditions. Acrylic copolymers were grafted on nanocellulose structures leading to high improvement of properties: increase of the contact angle at 84° indicating hydrophobic properties, reduced water absorption, increased onset degradation temperature with over 60 °C, a uniform polymer coating and maintaining the porous structure. 3D composite structures based on nanocellulose and hydrophobic biopolymers, poly (3-hydroxybutyrate) (PHB), poly (3-hydroxybutyrate co-3-hydroxyvalerate) (PHBV) and poly (3-hydroxyoctanoate) were obtained by (i) impregnating functionalized nanocellulose structures with solutions of various biopolymers and (ii) mixing cellulosic nanofibres with the polymer solutions. Depending on the working conditions, the thermal stability of the composite structures increases by 100 °C compared to the untreated 3D cellulose structure. The report on the mechanical properties of the 3D crosslinked cellulose structures and the methodology for obtaining 3D structures from nanocellulose/hydrophilic polymers and from nanocellulose/hydrophobic biopolymers were released. The non-patentable results obtained in this project were disseminated through 6 articles, 5 of which were published, 4 in ISI journals with high impact factor and one being in the evaluation phase. The results were also disseminated in 8 international conferences.
CELL-3D has as main objective to design new 3D nanocellulose structures for tissue engineering. The new 3D structures should meet the required chemical, mechanical and structural properties needed in regenerative medicine. To address the overall objective of this project, several specific objectives will be considered: (1) understanding the influence of the surface modification of nanocellulose on the 3D structures, (2) understanding the influence of composition and processing parameters on the properties of 3D structures; (3) characterization of the properties and morphology of nanocellulose 3D structures in different environments.
The 3D nanocellulose structures will be obtained by new methods based on the understanding of the relationship between structure, processing parameters and properties of nanocellulose 3D scaffolds. The results will be disseminated by articles and communications.
1. Adriana Nicoleta Frone, Denis Mihaela Panaitescu,* Cristian Andi Nicolae, Augusta Raluca Gabor, Roxana Trusca, Design of nanocellulose 3D structures for biomedical applications by functionalization and cross-linking, Submitted to Applied Surface Science, november 2018
2. Sorin Vizireanu, Denis Mihaela Panaitescu,* Cristian Andi Nicolae, Adriana Nicoleta Frone, Ioana Chiulan, Maria Daniela Ionita, Veronica Satulu, Lavinia Gabriela Carpen, Simona Petrescu, Ruxandra Birjega, Gheorghe Dinescu, Cellulose defibrillation and functionalization by plasma in liquid treatment, Scientific Reports(2018) 8, 15473
3. Denis Mihaela Panaitescu, Eusebiu Rosini Ionita, Cristian Andi Nicolae, Raluca Augusta Gabor, Maria Daniela Ionita, Roxana Trusca, Brindusa-Elena Lixandru, Irina Codita, Gheorghe Dinescu, Poly(3-hydroxybutyrate) modified by nanocellulose and plasma treatment for packaging applications, Polymers (2018) 10, 1249
4. Denis Mihaela Panaitescu*, Adriana Nicoleta Frone, Ioana Chiulan, Cristian Andi Nicolae, Roxana Trusca, Marius Ghiurea, Raluca Augusta Gabor, Mona Mihailescu, Angela Casarica, Irina Lupescu, Role of bacterial cellulose and poly(3-hydroxyhexanoate-co-3-hydroxyoctanoate) in poly(3-hydroxybutyrate) blends and composites, Cellulose (2018) 25, 5569–5591
5. Adriana Nicoleta Frone, Denis Mihaela Panaitescu,*, Ioana Chiulan, Cristian Andi Nicolae, Angela Casarica, Raluca Augusta Gabor, Roxana Trusca, Celina Maria Damian, Violeta Purcar, Elvira Alexandrescu, Paul Octavian Stanescu, Surface treatment of bacterial cellulose in mild, eco-friendly conditions, Coatings (2018) 8, 221
6. Ioana Chiulan, Adriana Nicoleta Frone, Calin Brandabur, Denis Mihaela Panaitescu, Recent Advances in 3D Printing of Aliphatic Polyesters, Bioengineering (2017) 5(1) 2.
1. Denis Mihaela Panaitescu, Adriana Nicoleta Frone, Ioana Chiulan, Cristian Nicolae, Raluca Gabor, Elvira Alexandrescu, Angela Casarica, Design of nanocellulose aerogels by functionalization and cross-linking, 11th International conference on Advanced Nanomaterials, Aveiro, Portugal, 18-20 July 2018
2. Adriana Nicoleta Frone, Ioana Chiulan, Raluca-Augusta Gabor, Elvira Alexandrescu, Cristian-Andi Nicolae, Denis Mihaela Panaitescu, 3D structures from cross-linked nanocellulose, 6th Portuguese Young Chemists Meeting - PYCheM2018, Setubal, 15-18 May 2018
3. Adriana Nicoleta Frone, Denis Mihaela Panaitescu, Ioana Chiulan, Raluca Augusta Gabor, Cristian Andi Nicolae, Thermal behavior of biodegradable polyesters based membranes, 12th European Symposium on Thermal Analysis and Calorimetry, Brasov, Romania, 27-30 August 2018
4. Denis Mihaela Panaitescu, Adriana Nicoleta Frone, Ioana Chiulan, Cristian Andi Nicolae, Augusta Raluga Gabor, Madalina Calarasu, Sergiu Stoian, Roxana Trusca, Angela Casarica, New 3D structures from nanocellulose and biopolymers, XXXVth National Conference of Chemistry, Caciulata, Romania, 2-5 October 2018
5. Denis Mihaela Panaitescu, Adriana Nicoleta Frone, Madalina Calarasu, Sergiu Stoian, Porous structures from nanocellulose and biopolymers for biomedical application, 9th International Conference on Biopolymers and Polymer Sciences, Bucharest, Romania, 19-21 November 2018
6. Sergiu Stoian, Adriana Nicoleta Frone, Denis Mihaela Panaitescu, Mona Mihailescu, Roxana Trusca, Cristian Andi Nicolae, Augusta Raluga Gabor, Physico-chemical characterization of surface modified cellulose, Sixth edition of the International Colloquium ‘Physics of Materials’, Bucharest, Romania, 15-16 November 2018
7. D. M. Panaitescu, A. N. Frone, I. Chiulan, R. A. Gabor, C.A. Nicolae, M. Ghiurea, D. Florea, C. M. Ninciuleanu, Surface functionalization of nanocellulose for biomedical applications, The XIIIth International Symposium "Priorities of Chemistry for a Sustainable Development – PRIOCHEM”, Bucharest, 25 - 27 October 2017