NIRT: Self-Assembled Nanohydrogels for Differential Cell Adhesion and Infection Control

1. Si Si + PLL Si + PLL + nanohydrogel S. epi osteoblast Objective Lens S. epidermidis Therapeutic Delivery/ Host defense mechanism vortex Protein Conditioning substrate PEGDA, AA, photo initiator and DCM Add DI water during stirring self-assembled nanohydrogels repulsive adhesive Osteoblast Glass substrate Sonicate for 30 min in darkness UV for 15 min during sonication attachment Polysaccharide secretion Maturation and biofilm growth Release of planktonic progeny polycation primer layer Relevant Biomaterial/ Engineered Material Electrostatic Self Assembly - - - - - - - - - - - Si Global Orthopaedic Markets (2005) Deposition Efficiency A Si wafer was used as substrate and hydroxylated by NaOH. It was immersed in PLL solution to get a positive charged PLL primer layer. Bacterial biofilms form complex and hierarchically structured communities which are as much as 10kx more resistant to antibiotics than planktonic bacterial. • Infection by Staphylococcal Biofilms • S. aureus (40%) • S. epidermis (20%) + + + + + + + + + + + + + + + + + + + + + + - - - - - - - - - - - - - - - - - - - - - - ~1 m Si Si Cell-Interactive nanohydrogels hierarchically structured on the surface of a macroscopically beaded surface of a modern orthopaedic implant. The PLL coated wafer was then immersed in a nanohydrogel suspension at pH 7.4 for electrostatic gel deposition. ~2 mm Source: Merrill Lynch Courtesy of G. Grobe DePuy Orthopaedics - - - - - - - - - - - - - - - - - - - - The biofilm cycle adapted from Sauer, Genome Biology, 2003) Reduced S. epi Adhesion ~350 m Osteoblasts before S. epidermidis inoculation Implement small pilot Develop draft modules Year 1 20x 20x 20x Implement larger pilot Revise draft modules Year 2 Finalize modules Dissemination Year 3 C12-reazurin, post-stained Devices integrated to a grit-blasted Ti alloy (top), a polished Ti alloy (middle), and a glass slide (bottom) CMFDA, pre-stained MC3T3-E1 osteoblast were seeded (1M/ml M-aMEM) in a prototype microchannel on a glass slide, cultured at 0.1 ml/min flow rate for 24h Dr. Ron Schreck from the Academies@Englewood/Dwight Morrow High School and ACS SEED student Ashley Contreras Osteoblasts co-cultured with S. epidermidis for 2h under flow + S. epidermidis CMFDA, pre-stained C12-reazurin/Sytox, post-stained 20x SYTO9 MC3T3-E1 osteoblasts were seeded (1M/ml) in a microchannel on a glassslide, cultured in M-aMEM at 0.1 ml/min flow rate for 24h, and then inoculated with 103 CFU/ml S. epidermidis, and cultured for 2h S. epidermidis, 108 CFU/ml, 5h flow culture in M-aMEM NIRT: Self-Assembled Nanohydrogels for Differential Cell Adhesion and Infection Control Matthew Libera, Woo Lee, Svetlana Sukhishvili, Hongjun Wang, and Debra Brockway Stevens Institute of Technology, Hoboken, New Jersey 07030 Project Overview Infection occurs in approximately 0.5 – 5% of all hip and knee replacements. It is a catastrophic problem, because bacteria that colonize an implant surface develop into biofilms where they are as much as 10,000 times more resistant to antibiotics than planktonic bacteria. The most effective therapy is to remove an infected implant, cure the infection, and then pursue a subsequent revision surgery. The consequences to patient well being and medical cost in this situation are compellingly significant. At its core, implant infection is a biomaterials problem. While surfaces have been developed which repel bacterial adhesion – e.g. PEGylated surfaces – these also repel the eukaryotic cells necessary for the development of a healthy implant-tissue interface. Instead, surfaces are needed that are differentially adhesive, i.e. that it promote eukaryotic (e.g. osteoblast) adhesion and proliferation while simultaneously repelling bacteria. This is a fundamental biomaterials problem that remains unsolved. This project explores a new mechanism to create differentially adhesive surfaces. We hypothesize that heterostructures of nanosized hydrogels self assembled in 2Dover micrometer length scales willallow focal contact formation and subsequent osteoblast adhesion but prevent bacterial adhesion. Infection: A Major Mode of Orthopaedic Implant Failure Differentially Adhesive Surfaces - Repulsive to Bacteria but Attractive to Eukaryotic Cells • Infection Rates • Hips 0.3 - 1% • Knees 1 - 4% • Fixation devices > 15%e.g. Intramedullary trauma rods Multiplexed Microfluidic Methodology for Evaluation of Differential Adhesion Broader Impact: A Partnership to Introduce Nanotechnology Research in High School Classrooms Goals of the Outreach Effort- Expose high school students to nanotechnology-based research - Demonstrate societal relevance- Enhance and modernize topics taught in standard high school biology and chemistry Nanohydrogel Synthesis and Self Assembly Emulsion Polymerization Prototype device bonded to glass Attributes of the Module- Ease of implementation in biology and chemistry courses- Minimal time requirement for implementation- Contain a hands-on or laboratory activity- Address National Science Education Standards (NSES) Stevens undergraduate Zareen Mobin working with Ms. Clare Kennedy fromthe Academies@Englewood/Dwight Morrow High School CIESE has nearly 20 years of K-12 curriculum and professional development expertise in STEM education, and has impacted over 20,000 educators worldwide