# Steering the Clinical Translation of Delivery Systems for Drugs and Health Products
## 3 Poster Presentations
### Biodegradable Nanoparticles for Ophthalmic Diseases  
[PERSON] * and [PERSON]  
Department of Chemical, Biological, Pharmaceutical and Environmental Science, University of Messina, V.le F. Stagno D'Alcontres, 98166 Messina, Italy  
* Correspondence: [EMAIL_ADDRESS]  
The bacteria can form ocular biofilms. The biofilm has been extensively studied by [PERSON] and his research group [73]. Briefly, a biofilm can be defined as a colony of microorganisms, in which they are attached to each other and generally have the ability to adhere to a surface, such as the eye. Biofilm formation gives individual bacteria the ability to collaborate and adapt to difficult environmental conditions. There is growing evidence that biofilms are the cause of different types of eye infections, many of which are resistant to antibacterial treatment [73]. Presently, antibiotic resistance represents a problem for world health, because it causes persistent infections and mortality [74]. Treatment with the free drug often requires high toxic doses for the patient, with serious or deadly side effects [75]. A novel anti-biofilm strategy is needed. In this study, we designed chitosan nanoparticles (CH-NPs) loading levofloxacin (LEF) for the treatment of ophthalmic diseases. LEF is an antibiotic active towards different types of ocular infections. The ophthalmic aqueous formulation of LEF has been approved in Europe, USA and Japan. However, this formulation could not be sufficient to penetrate bacterial biofilms and consequently the treatment with free LEF may not have therapeutic efficacy. Chitosan (CH) is a cationic polysaccharide, widely used in the medical and pharmaceutical fields due to its high biocompatibility, biodegradability, mucoadhesive ability and non-toxicity. It also shows good antibacterial properties. In this study, CH-NPs were prepared by ionotropic gelation method that exploits the electrostatic interaction between positively charged CH and negatively charged gelling agents. Different types of polyanions were used that are sodium tripolynphosphate (TPP) or sulfobutylether-\(\beta\)-cyclodextrintrin (SBE-\(\beta\)-CD). Low molecular weight CH was solubilized in 1% acetic acid solution, after brought to pH 5. Aqueous solutions of different polyanions were added dropwise to the CH solutions under continuous magnetic stirring for 30 min. The colloidal suspensions were centrifuged twice at 13000 rpm for 30 min, to allow optimal separation of the pellet from the supernatant. The pellets were re-suspended in 1 mL of water containing trehalose (5%, w/v) as a lyoprotectant agent and finally freeze-dried. The supernatants were collected and used for determination of encapsulation efficiency (E.E.) of LEF. Morphology of the CH-NPs was investigated by scanning transmission electron microscopy (STEM). We obtained spherical and small CH-NPs, with sizes between 250 and 350 nm, which showed positive zeta potential values, these needed for the interaction of the NPs with the biofilm negatively charged. STEM images demonstrated for the CH-NPs gelified with TPP (CH-NPs/TPP) homogeneous morphology, instead NPs prepared with SBE-\(\beta\)-CD showed a dense core surrounded by a less dense shell probably made of not gelified CH chains. CH-NPs/TPP showed higher yield percentage and EE percentage with respect to CH-NPs/SBE-\(\beta\)-CD; however, the drug content is higher for these latter NPs. This could suggest the presence in solution of a complex between LEF and the macrocycle. To clarify this hypothesis, we investigated the complexation by using UV-Vis and 1H-NMR spectroscopy. A 1:1 interaction between LEF and the CD was revealed. In vitro release of LEF from CH-NPs was determined usingdialysis membranes, in the absence and presence of lysozyme, this presents in the eyes at high concentrations. In all cases the presence of lysozyme increased the amount of LEF released within 24h. In conclusion, LEF can be efficiently encapsulated in CH-NPs.