Nanoparticles (NPs) provide significant benefits to medicine. Targeting of their action site, delivery, and reduction of intrinsic toxicity still remain challenging. Here focus is on the preparation and characterization of bio-inspired and biomimetic hybrid nano-materials. These have unique features in terms of size, surface area, chemical composition, solubility and local morphology. Perspectives are in biomedicine and transfection technologies, although potential hazard to humans must has to be accounted for.
The design of multi-functional hybrids, either "soft" or "hard", may improve current formulations and reduce some inherent drawbacks. The proposed bottom-up strategy provide peculiar structural arrangements for self-complementing NPs complement in hybrids. Their clustering induces outstanding features and performances not occurring in the original form. The size, morphology and physico-chemical properties of NPs can be tuned by suitable chemical functionalization, introducing sensitivity to temperature, pH, or ionic strength.
The complex architectures considered here are:
1. cat-anionic vesicles surface-decorated with proteins or nucleic acids
2. DNA- or RNA-wrapped carbon nanotubes (CNTs)
3. dispersion of nucleic acids-wrapped CNTs in vesicular media
4. lipopeptides with pH and/or temperature-dependent association features
5. pH and thermosensitive peptide-polymer conjugates
6- internalizing magnetic NPs in vesicles/liposomes
Complementary experimental methods, such as dynamic light scattering, atomic force and electron microscopies, NMR, circular dichroism, fluorescence, electrophoretic mobility, relaxation spectroscopies will help optimizing size, shape, charge and hydrophobicity of nano-hybrids. Attention is focused on the control of surface potentials and surface coverage, which induce interactions among NPs and favor the formation of the desired hybrids. Finally, the toxicity of the most promising materials will be assessed.
Our proposal deals with the synthesis and characterization of NHs described above in detail. The synthetic and physico-chemical characterization steps will be performed by many different and complementary approaches. The reasons for joining together diverse expertise are dictated by the complexity of materials to be obtained. To this end, competences related to colloid chemistry, peptide synthesis, preparation of self-assembling polymers by controlled radical polymerization, structural characterization, will be properly combined to obtain NHs with unprecedented properties.
We plan to prepare NHs and elucidate their structural/morphological features by different physico-chemical and advanced microscopy methods. This procedure will avoid undesired effects, such as phase separation. Furthermore, surface-functionalization will be carried out by appropriate strategies to improve the biocompatibility of NHs: CNTs shall be wrapped with biopolymers, such as proteins, DNA, RNA, and pH-, or thermo-sensitive synthetic polymers. Similar considerations apply to all other systems described in this proposal, namely lipo-peptides and peptide-polymer conjugates with pH- and thermal-dependent association features.
The research and innovation proposed by the project will contribute to the development of innovative materials and nano-based products. The combination of the different research experience and skills of the partners will pave the way towards these ambitious goals.
Concerning the synthetic part, we shall make use of advanced strategies extensively used in a recent past. In particular, use of atom transfer radical polymerization (ATRP) allows achieving homogeneous polymers devoid of size-polydispersity effects. This point is of major relevance since processes occurring in bio-systems are extremely sensitive to the size and conformation of polymers entering cells and tissues. In addition, pH- and thermo-modulation of the polymer moieties may provide differential adsorption, and the subsequent income into cells. Therefore, the expected action on the receptors to be reached can be optimized.
As regards the preparation of hybrid systems, these are generally obtained by covalent bonds between different NPs. Alternatively, interactions controlled by surface energy terms (including surface electrical potentials) can be optimized. In a given medium, in fact, NPs self-assemble due to the combined action of reactivity (if any), electrostatic and volume fraction energy terms. The resulting packing modes can be controlled in such a way to ensure a given NHs structure for indefinitely long times, if this is required. In other cases, NHs can operate as matter reservoirs; this is at the basis of controlled release technologies.
Physico-chemical investigations will be performed to characterize liposome-MNPs systems by using most spectroscopic techniques indicated above (plus FTIR and MRI) and by Fluorescence Microscopy, AFM, TEM and SEM). Exploiting our experience in the synthesis of MNPs functionalized with fluorescent probes, antibodies and drugs, in vitro tests on healthy and/or tumor cellular cultures will be conducted to verify if, and in which way, lipid covers favor MNPs internalization.
The most relevant properties of NHs devoted to bio-applications are intrinsically connected to their surface properties, which ensure recognition from cells and tissues. Therefore, a convincing analysis of fundamental aspects controlling the stabilization procedures will essentially focus on: i) surface charge density and electrical potentials of NHs; ii) their interfacial properties; iii) hydrophobicity; iiii) deformability and elasticity. In addition, transitions from one state to another may occur if temperature, pH, and ionic strength are properly tuned.
All such properties can be presumably optimized by a concerted combination of expertise of members in the group. Our competences, in fact, span from colloid and surface sciences to biophysical, biochemical and synthetic expertise. The same holds for junior researchers involved in the proposal, which have complementary competences and will surely contribute significantly to a successful fate of the whole project.