(W1130-12-81) Curcumin Nanocrystals-in-Nanofibers as a Promising Platform for the Management of Periodontal Disease

Purpose: It is estimated that oral diseases affect 3.5 billion people globally [1], with periodontal diseases (PD) affecting nearly half of adults older than 30 years and 70% of adults older than 65. Although mostly preventable, oral diseases pose a considerable health burden to people living in many countries, with consequences that range from pain and discomfort to disfigurement and even death [1]. PD affect the tissues surrounding and supporting the teeth and are often related to exacerbated proliferation of the mouth microbiota, leading to infection and inflammation of the tissues that surround the tooth [2]. The treatment of PD often requires mucogingival procedures in which diseased soft tissues in the periodontal pocket are removed and the function of the tooth and gum are restored. These procedures require the administration of systemic antibiotics and anti-inflammatory drugs; however, there are only a limited number of products available in the market to minimise pain and microbial growth at a local level. Curcumin (CUR) is a broad-spectrum antibacterial agent and has antioxidant and anti-inflammatory action due to its structural characteristics [3]. Despite the proven efficacy and pharmacological safety of CUR, its poor bioavailability has greatly limited its approval for widespread use as a therapeutic agent. The aim of this work was to design and manufacture CUR-NCs and include them into fast dissolving electrospun NFs in order to obtain a novel platform (NCs-in-NFs) for efficient delivery of hydrophobic drugs to affected tissues.

Methods: CUR-NCs were prepared using a lab-scale media milling technique described in previous publications. Various stabilisers at concentrations ranging from 0.5-2.5%w/v were used in a rationalised manner to obtain NCs candidate formulations. The NCs were then incorporated into polyvinyl alcohol (PVA, MW 31–50 kDa) NFs. For the electrospinning process, the syringe was equipped with an 18-gauge needle and connected to the syringe pump with a delivery rate of 0.25 mL/hr. The applied voltage range was 18-20 kV. After about 2 hours, NFs were collected from the metal plate collector, placed 15 cm horizontal distance from the needle tip. The resultant NCs-in-NFs were fully characterised physiochemically, including FTIR, DSC/TGA, PXRD, SEM, Raman spectroscopy, NCs redispersion, and in vitro release rate. The ex vivo mucosal deposition using neonatal porcine tissues was assessed.

Results: CUR-NCs were stabilised with Poloxamer 188® and showed a particle size of 93.29 ± 0.49 nm and a PDI of 0.249 ± 0.003. NCs-in-NFs were obtained successfully by electrospinning using polyvinyl alcohol, giving place to film-like materials (Figure 1A). The morphology of the NFs containing indented NCs was evidenced using SEM (Figure 1B). The drug content of the NCs-in-NF, determined by HPLC, was 52.99 ± 9.37 µg/cm² (Figure 1C), and the NCs were dispersed from the NFs with similar nanoparticle as that of the original formulation (Figure 1 D and E). The NFs were able to dissolve quickly in water (Figure 1F), exposing the NCs for subsequent dissolution. FTIR studies revealed no chemical interactions between drug and materials or formation of degradants, and Raman microscopy evidenced a uniform distribution of CUR in the novel patches. Differential scanning calorimetry demonstrated a partial amorphization of the systems, attributed to a high polyvinyl alcohol proportion in the final formulation. The novel NCs-in-NFs released the drug in vitro at a significantly higher rate than the control groups, as observed in Figure 2A. At day 40 (study endpoint), the NCs-in-NFs released ~100% of CUR, a PM with the same composition of the NCs released 7.81% of the drug and CUR only released 6.44% of the drug. Finally, mucosal deposition studies demonstrated a 10-fold higher capacity of the novel NCs-in-NFs system to deposit CUR ex vivo using excised neonatal porcine mucosal tissue, when compared to the control group (Figure 2B). This agrees to the results of the fluorescent microscopy images of the mucosal tissues after the deposition studies, where the sample treated with PM-NF showed an apparently less intense fluorescence and granular structures with intense fluorescence borders, which were identified as drug particles (Figure 2 C and D).

Conclusion: This work describes the incorporation of drug NCs into NFs for the first time and evaluates the applicability of this platform to deliver hydrophobic drugs to mucosal tissues with potential application in PD. Overall, this novel platform showed promise regarding the delivery of CUR the buccal mucosa; however, other interesting applications could be explored, including other poorly soluble drugs, management of diseases that affect other mucosal tissues, and tissue regeneration. Crucially, further in vitro and in vivo experiments would be required to gain deeper understanding of translational aspects of this novel platform.

References: 1- WHO. (2022, November 18). Oral Health. https://www.who.int/news-room/fact-sheets/detail/oral-health
2- Kinane, D et al. (2017). Periodontal diseases. Nature Reviews Disease Primers, 3(1), 17038.
3- Zorofchian et al (2014). BioMed Research International, 2014, 186864.

Figure 1. NCs-in-NFs formulation. A-NCs-in-NFs patch. B- SEM image with NCs indented in the NFs structure. C- Drug content of NCs-in-NFs and physical mixture (PM)-loaded NFs. D, E- Particle size and PDI of redispersed NCs, respectively. F- NFs dissolution in water

Fig. 2. A in vitro drug release. B- Mucosal deposition. Fluorescence microscopy of PM-NFs (C) and NCs (D).