Pitt | Swanson Engineering
Polymeric Layer-By-Layer Coatings

Polymeric Layer-By-Layer Coatings

A series of composite degradable, inorganic conversion coatings paired with bioactive polyelectrolyte multilayer (PEM) coatings have been developed for the use on pure magnesium or magnesium-based alloys. Inorganic/PEM coatings may serve many purposes when applied to degradable magnesium implants, including improved biocompatibility and osseointegration, controlled corrosion resistance, and controlled delivery of drugs, growth factors or other biomolecules from the implant surface. The development of such degradable, drug-eluting coatings on magnesium alloy implants could have a significant impact in the field of tissue regeneration including bone and represent convenient strategy to improve the efficacy of stand-alone magnesium alloy implants or other metal based implants. Although previous coating research has attempted to address individual needs of alloy coatings, through ceramic or polymeric coatings, the inorganic/PEM composite coatings pose the potential to address numerous needs with one coating technology. The current work reports the fabrication of multilayered coatings, consisting of natural and synthetic polymers, assembled using layer by layer (LbL) technique under physiological conditions following pretreatment of alloy substrates under alkaline and/or fluorinating conditions. PEM coating systems studied have covered a wide array of natural and synthetic polymers, including the use of alginate (ALG) coupled with poly-L-lysine (PLL) and poly (lactic-co-glycolic acid) (PLGA) or polycaprolactone (PCL) coupled with poly(allylamine hydrochloride) (PAH). Preliminary results collectively show the potential use of LbL coatings on magnesium based degradable scaffolds to improve their surface bioactivity. Release of a model protein, Bovine Serum Albumin, from some of these LbL coated magnesium alloys show control release of the protein with time and hence these novel coating systems can act like smart degradable delivery vehicles for inorganic and organic molecules.



LBL Fig 1

Measurements of daily released magnesium ion concentration in extracted incubation media. For every time point, all coated samples show lower ion concentrations than the uncoated AZ31.

LBL Fig 2

Release profile of BSA from LbL coated substrates in Hanks balance salt solution. Group I: FAZ31 with (Alg/PLL) 5 + (BSA/PLL) 5, Group II: FAZ31LC with BSA for 12 hr adsorption.


LBL Fig 3

Cell morphology of MC3T3 osteoblasts (a-d) and hMSCs (e-h) observed at 24 hours post seeding through actin-nucleus co-staining on uncoated AZ31 (a & e), PCL (b & f), PLGA 50:50 (c & g) and PLGA 75:25 (d & h)


Publications:

*Singh SS, Roy A, Lee B, Ohodnicki J, Loghmanian A, Banerjee I, Kumta PN, “An Evaluation of Strontium Doped Calcium Phosphate Coatings on AZ31”, 2013, 2013, Under Revision

*Nicole Ostrowski, Boeun Lee, Nathan Enick, Benjamin Carlson, Sangeetha Kunjukunju, Abhijit Roy, Prashant N. Kumta. "Corrosion Protection and Improved Cytocompatibility of Biodegradable Polymeric Layer-by-Layer Coatings on AZ31 Magnesium Alloys" Acta Biomaterialia, In Press

*Sangeetha Kunjukunju, Abhijit Roy, Madhumati Ramanathan, Boeun Lee, Joe E. Candiello, Prashant N. Kumta. "Layer by Layer approach to natural polymer derived bioactive coatings on magnesium alloys" Acta Biomaterialia, In Press

*Ostrowski, N., Lee, B., Roy, A., Ramanathan, M., Kumta, PN. (2012) “Biodegradable poly(lactide-co-glycolide) coatings on magnesium alloys for orthopedic applications.” Journal of Material Science: Materials in Medicine 24 (1) 85-96

*Sangheeta K, Roy A, Singh SS, “Novel Alginate Based Coatings on Mg Alloys”, Materials Science & Engineering B 176 (2011) 1703-1710

*Roy A, Singh SS, Lee B, Kumta PN, “Novel Sol-gel Derived Calcium Phosphate Coatings on Mg4Y Alloys”, Material Science & Engineering B 176 (2011) 1679-1689

*Singh SS, Roy, A, Lee B, Kumta PN, “Aqueous Deposition of Calcium Phosphate and Silicate Substituted Calcium Phosphate Coatings on Mg Alloys”, Material Science & Engineering B 176 (2011) 1695-1702

*Sung Jae Chung, Abhijit Roy, Daeho Hong, John P. Leonard, Prashant N. Kumta, Microstructure of Mg–Zn–Ca thin film derived by pulsed laser deposition. Mater. Sci. Eng. B 176 (2011) 1690-1694

* Sung Jae Chung, Abhijit Roy, Daeho Hong, John P. Leonard, Prashant N. Kumta, Microstructure of Mg–Zn–Ca thin film derived by pulsed laser deposition. Mater. Sci. Eng. B 176 (2011) 1690-1694

Patents: "Development of Smart Polyelectrolyte Layer-by-Layer Coating Systems on Mg Alloys for Achieving Tailored Corrosion Properties, Improved Bioactivity and Delivery of Inorganic and Organic Biomolecules" Provisional Patent application filed.

Affiliated Lab Members: Dr. Sangeetha Kunjukunju, Dr. Abhijit Roy, Satish Singh, Sung Jae Chung, Nicole Ostrowski, John Ohodkicki, Sudhanshu Shekhar

Collaborators & Affiliations: NSF Engineering Research Center for Revolutionizing Metallic Biomaterials