Self-assembled Peptides as Drug Delivery Molecules for transport across the Biological Barriers

Transcription

1 Self-assembled Peptides as Drug Delivery Molecules for transport across the Biological Barriers Porter, S., McCarthy, H., & Laverty, G. (2017). Self-assembled Peptides as Drug Delivery Molecules for transport across the Biological Barriers. Paper presented at 39th All Ireland Schools of Pharmacy Research Conference, Cork, Ireland. Document Version: Other version Queen's University Belfast - Research Portal: Link to publication record in Queen's University Belfast Research Portal Publisher rights 2017 The Authors. General rights Copyright for the publications made accessible via the Queen's University Belfast Research Portal is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. Take down policy The Research Portal is Queen's institutional repository that provides access to Queen's research output. Every effort has been made to ensure that content in the Research Portal does not infringe any person's rights, or applicable UK laws. If you discover content in the Research Portal that you believe breaches copyright or violates any law, please contact openaccess@qub.ac.uk. Download date:08. Nov. 2018

2 OVERCOMING BIOLOGICAL BARRIERS: PEPTIDE NANOTUBES FOR DRUG DELIVERY

3 Biological barriers Biological barriers inhibit drug delivery throughout the body For efficient drug delivery, drugs must be able to reach their target site of action The blood brain barrier is very problematic for drug delivery Large gap in adequate care for patients for particular diseases: brain tumors, Parkinson's, Alzheimer's CRS Controlled release society. [ONLINE] Available at: [Accessed 16 April 2017].

4 The blood brain barrier For Transmembrane diffusion of small molecules: <400 Daltons and high lipid solubility Approaches to bypassing this barrier: Disruption of the blood brain barrier tight junctions (detergents or ultrasound) Receptor mediated transcytosis engage cell-surface receptors over expressed by brain cells. Adsorptive endocytosis of nanoparticles Jonathan C.H. Choi Jonathan C.H. Choi Research Group. [ONLINE] Available at: [Accessed 16 April 2017].

5 Peptide structure Ultra short peptide structure consisting of two amino acids Phenylalanine-Phenylalanine Molecular weight of Daltons Relatively easy manufacture process due to the short length peptides become increasingly difficult to manufacture at high purities with increasing chain length NH 2 -( D )Phe-( D )Phe-COOH N H 2 O NH O OH

6 Self assembled peptide nanotubes

7 B: Adsorptive endocytosis (Previously demonstrated for nanotube structures) Astrocyte

8 Characterising the assembled secondary structure Circular dichroism spectra for assembled peptide nantotube structures: m d e g Large positive peak ~ 217 nm Characteristic of β-sheet assembly in peptides Useful to confirm presence of peptide nanotubes in absence of environmental microscope W a v e l e n g t h ( n m ) -5 0

9 Measuring zeta potential Particle charge is a key consideration when considering formulation of any nanoparticle Unfavourable charge pairing will lead to the repelling of the drug cargo from the nanoparticle Extremes of either positive or negative charge unfavourable for delivering across cell layers because it can lead to entrapment ph (n=3) Mean Zeta Potential (mv) (±0.49) (±2.37) Water World ONLINE ZETA POTENTIAL MEASUREMENT PROVIDES WATER TREATMENT CONTROL, COST REDUCTION. [ONLINE] Available at: 30/issue-10/features/automation-technology/online-zeta-potential-measurement-provides-water-treatment-control-cost-reduction.html. [Accessed 16 April 2017].

10 Encapsulation of Rhodamine B R h o d a m in e B e n c a p s u la t io n ( % ) Instead of beginning encapsulation and permeation studies with a drug, a fluorescent molecule is used for ease of screening Rhodamine B is chosen as a tracer molecule due to the previous zeta potential data, rhodamine should be positively charged at ph during the assembly process Rhodamine B is added while the peptide nanotubes are self assembling and are spontaneously incorporated into the tubes A maximum of 56 % encapsulation efficiency was observed P e p t id e c o n c e n t r a t io n ( m g / m l)

11 In-vitro blood brain barrier model Transwell inserts used to grow a brain endothelial cell layer on Semi-porous membrane containing defined pore size (0.4 micron) Cell layer grown on insert membrane creates two separate chambers separated by a brain endothelial cell layer (hcmec/d3 Cell) Nanotube suspensions loaded with a fluorescent marker can be loaded into top chamber Validate using TEER Brunswick laboratories Caco-2 Permeability Screening Assay (unidirectional/bidirectional). [ONLINE] Available at: [Accessed 16 April 2017].

12 Permeation across model At time zero peptide nanotube suspension loaded with rhodamine b is added to the top chamber of the transwell insert The bottom chamber is sampled over time and the fluorescence intensity of rhodamine b at 562/583 nm excitation/emission wavelengths is recorded Peptide nanotubes transport rhodamine over the cell monolayer and then begin to deassemble once they have reached the bottom compartment and are no longer in a peptide monomer saturated solution After 4 hours 2.4% of the total dose had crossed, which is reasonable considering the short time point P e r c e n t a g e t o t a l d o s e ( % ) T im e (m in )

13 Biocompatibility studies 4 Haemolysis of equine erythrocytes: Peptide nanotubes are incubated with horse red blood cells The percentage of red blood cells lysed can be calculated by measuring absorbance Gives an indicator of how compatible the treatments would be as an injectable H a e m o ly s is ( % ) P e p tid e c o n c e n t r a tio n ( m c g /m l)

14 N S N S N S N S P e r c e n t a g e v ia b ilit y ( % ) N S * * 0 * * P e p tid e c o n c e n t r a tio n ( m g /m l) Percentage of remaining viable NCTC 929 cells following 6-hour treatment with a range of peptide nanotube suspension concentrations using a MTS assay. Key: black column:. NS: no significant difference (P 0.05), *: P<0.01 significant difference between percentage viability of peptide nanotube treated cells and negative control. LIVE/DEAD stain of NCTC 929 cells following 6-hour treatment with peptide nanotube suspension. Live cells are stained green and dead cells are stained red. Scale bar represents 200 µm.

15 Conclusions Phenylalanine-phenylalanine peptides can self assemble into nanotube structures which can encapsulate fluorescent markers Preliminary studies have shown they have high biocompatibility and can permeate an in vitro blood brain barrier model

16 Thank you