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TRACK 5 TRACK 5 Technical Program

actions at nano- and micro-scales in response to integrated physical and Shida Miao, Wei Zhu, Nathan Castro, Lijie Zhang, The George
chemical stimuli. From these fundamental studies we can create both in vitro Washington University, Washington, DC, United States
and in vivo tissue models for precision tissue engineering and regenerative
medicine. The gold standard method for repair of bone defect is utilizing an autol-
ogous bone graft, but the availability of autologous bone graft is limited
12:00pm Flow-induced one-step process to synthesize function- and severe complications may generate in the graft harvesting. To replace
alized nanoporous scaffolds autologous bone, great efforts have been made on grafting materials and
fabricating techniques. In this study, we aim to 4D print nano smart biomi-
Technical Presentation. NEMB2016-5949 metic gradient bone scaffolds by a 3D printing guided approach to fill bone
defects through shape memory effect. The term “4D print” refers to added
shape transformation of printed construct on specific stimulation according
Amy Shen, Okinawa Institute of Science and Technology Graduate to requirements to achieve minimally invasive surgeries and perfect end-to-
University, Okinawa, Japan end joint connection. The term “smart” originates from the shape memory
behavior of the synthesized biocompatible polymers. To reach these goals,
Recently, we introduced a microfluidic assisted irreversible gelation pro- novel shape memory polymers with excellent biocompatibility and tunable
cedure to create stable nanoporous scaffolds with proper hydrodynamic shape changing effects are synthesized and cured with biomimetic nano-
conditions for a given surfactant solution, under ambient conditions. The ir- crystalline hydroxyapatite (nHA) in the presence of 3D printed sacrificing
reversible gelation results from the large shear and extension rates and total structures which are subsequently dissolved to create controllable and
strain generated by the flow through the microdevice containing micropost gradient porosity in the scaffolds. Morphology, thermal, mechanical and bio-
arrays. This microfluidic approach provides a simple platform for biomole- compatible properties as well as shape memory effect of the resultant po-
cule encapsulation in a porous scaffold. For proof of concept studies, we rous scaffolds are characterized using varied techniques. Fourier transform
used the micropost design to encapsulate enzyme horseradish peroxidase infrared spectroscopy (FTIR) and gel content analysis confirm the formation
(HRP) in an ionic surfactant-based nanogel for hydrogen peroxide sensing. of chemical cross-linking in obtained smart polymers which are synthesized
To extend this work, novel and versatile processing method based on micro- by reacting polycaprolactone triol and plant oil with multi-isocyanates.
fluidics is developed to synthesize functionalized nanoporous scaffolds for a Differential scanning calorimetry reveals an adjustable glass transition
variety of sensing applications. temperature in a range from 0 to 35 oC. Transmission electron microscopy
analysis shows that the nHA is 50-100 nm in length and 20-30 nm in width
(a) Glucose is an important carbohydrate that acts as a metabolic interme- of grain sizes similar to natural human bone nHA. Compression testing
diate and an energy source for cells. Glucose biosensors have found appli- indicates that the obtained polymers have close compression modulus to
cations in biological and clinical studies (e.g, blood glucose sensing), food polycaprolactone which is widely utilized as bone scaffold material, and fully
processing, and textile industry. Electrochemical glucose sensors are widely interpenetrating polymeric networks are formed in fully cross-linked polymer
used due to their low-cost, fast time-response, and simple operation proce- networks. Scanning electron microscope analysis shows that the nHA is
dures. In an electrochemical glucose sensor, molecular recognition enzymes distributed evenly in the scaffold and micro pores are present in gradient
such as glucose oxidase (GOx) need to be immobilized on electrodes. In from top to bottom of the scaffold, which mimics the non-uniformly distrib-
the presence of molecular oxygen, immobilized GOx then catalyzes the ox- uted porosity in natural bone. Shape memory test results show that the 4D
idation of glucose to gluconolactone, and generates hydrogen peroxide as printed nanocomposite scaffolds display finely tunable recovery speed and
a byproduct, where two protons and two electrons are released during the exhibit greater than 90% shape fixing at -18 or 0 oC and full shape recovery
reaction. The transfer of the released electrons (current) is the physical pa- at human body temperature. With polycaprolactone serving as a control, hu-
rameter sensed during the redox reaction between GOx and glucose. Here, man bone marrow-derived mesenchymal stem cell shows significant higher
a simple microfluidic platform is utilized to immobilize glucose oxidase (GOx) proliferation and osteogenic differentiation. The current work will advance
in a nonionic micellar scaffold. The immobilized GOx are verified by using a the future design and development of novel and functional bone healing
combination of cryogenic electron microscopy (cryo-EM), scanning electron nanocomposite scaffolds with advanced 4D printing technology and highly
microscopy (SEM), and ultra-violet spectroscopy (UV). Chronoamperometric biocompatible smart biomaterials.
measurements are conducted on nanogel-GOx scaffolds under different
glucose concentrations, exhibiting linear amperometric responses. With- 12:40pm Electrospun Patches for the Controlled Release of
out impacting the lifetime and denaturation of GOx, the nonionic nanogel Growth Factors to Enhance Vascularization in Regenerative
provides a favorable microenvironment to GOx as in biological media. This
flow-induced immobilization method in the nonionic nanogel host matrix Medicine Applications
opens up new pathways for designing simple, fast, biocompatible, and
cost-effective process to immobilize biomolecules that are averse to ionic Technical Presentation. NEMB2016-6091
environments.
Laura Pandolfi, Houston Methodist Research Institute, Houston,
(b) A simple and rapid flow-induced microfluidic process is employed to TX, United States, Francesca Taraballi, Houston Methodist Re-
disperse and encapsulate low volumes of single-walled carbon nanotubes search Inst., Houston, TX, United States, Silvia Minardi, Depart-
(SWCNTs) in wormlike micellar networks, thereby forming an electro-conduc- ment of NanoMedicine, Houston Methodist Research Institute,
tive porous scaffold. SWCNTs with anionic surfactant sodium dodecyl sulfate
(SDS) are first mixed with an aqueous wormlike micellar solution consisting Houston, TX, USA, Houston, TX, United States, Xuewu Liu, Mauro
of cationic surfactant cetyltrimethylammonium bromide (CTAB) and organic Ferrari, Houston Methodist Research Institute, Houston, TX, United
salt sodium salycilate (NaSal). The precursor mixture is then pumped through States, Ennio Tasciotti, The Methodist Hospital Research Institute,
a microfluidic device containing hexagonal microposts at room temperature Houston, TX, United States
and ambient pressure, developing a soft scaffold with entangled bundle-like
structures, containing interconnected SWCNTs and wormlike micelles. One- Tissue restoration is a complex process orchestrated by the presence of
step microfluidic process presented in this work opens a new pathway to specific bioactive molecules and by their spatio-temporal distributions. A
disperse and encapsulate SWCNTs in a micellar matrix without involving combination of growth factors (GFs) with different release kinetics has been
chemical reactions under ambient conditions, with promising potentials for shown to be beneficial in boosting tissue regeneration. In particular, the
sensing, encapsulation, and catalysis applications. synergistic effect of platelet-derived growth factor (PDGF-BB) and vascular
endothelial growth factor (VEGF) has been shown to enhance proliferation,
12:20pm 4D printed biomimetic nano smart bone scaffold migration and growth of endothelial cells, enhancing in situ neovasculariza-
tion. 65
Technical Presentation. NEMB2016-5957
The ability to control the spatio-temporal release kinetics of GFs is crucial