Page 55 - ASME_NEMB_2016_Program

TRACK 4 TRACK 4 Technical Program

In order to be effective, a new generation of therapeutics (siRNA, miRNA, mixed with 0.25% Irgacure 2959 photoinitiator was injected into a Teflon
mmRNA) has to be delivered directly into the cell cytoplasm of the diseased rectangular mold and subsequently shone with UV light to prepare a sol-
target site. This goal can only be achieved only by a delivery platform that si- id crosslinked hydrogel samples. Hydrogels samples were subsequently
multaneously accomplishes two tasks: its accumulation at the cancer lesion immersed in 1M HCL solution containing different amounts of ammonium
and the endolysosomal escape of its payload. In this study, we describe the persulfate (APS) and hexane solution with aniline monomers, to obtain
fabrication protocols of a new drug delivery systems able to enhance the hydrogel-Pani composites. Fourier transform infrared spectroscopy (FTIR)
effects of siRNA based treatments. We developed a new one-pot synthesis was used to confirm the presence of aniline within the hydrogel matrix.
protocol to fabricate hybrid nanoparticles formed by a nanostructured, inor- Swelling ratio, compressive modulus and contact angle measurements were
ganic silica core and an organic pH-responsive hydrogel shell. This easy-to- carried out. The biocompatibility and ability to adhere to composite sam-
perform oil-in-water emulsion process synthesizes fluorescently-doped silica ples, were tested by seeding C3H/10T1/2 murine mesenchymal progenitor
nanoparticles wrapped within a tunable coating of cationic poly(2-diethylam- cells (10T1/2s). Viability and morphology of adhered cells were quantified.
inoethyl methacrylate) hydrogel. Electron microscopy and dynamic light scat- Digital projection stereolithography, which consists of a UV light source, a
tering analysis demonstrated that the nanoparticles were uniformly coated digital light processing (DLP) chip and computer controlled stages (Newport
with the hydrogel and dispersed in the aqueous phase. Thermogravimetric 426/433 series) was used to print hexagonal microgeometries. Electrochem-
analysis showed that the formation of covalent chemical bonds between the ical Impedance Spectroscopy (EIS) was used to test the electrical properties
silica and the polymer increased the stability of the organic phase around of Pegda/Gelma-Pani composites using a three electrode system at a fre-
the inorganic core. The cationic nature of the hydrogel was responsible quency range of 0.02-20k Hz and an AC perturbation of 10 mV, as applied
for the pH buffering properties of the nanostructured system and this was by Solartron Analytical 1280Z working station. A custom-made direct current
assessed by titration experiments. Zeta-potential analysis showed that the resistance measurement system composed of a Data Acquisition (DAQ)
charge of the system reversed when it passed from acidic to basic pH and system and a planar gold measurement chip, was also used to quantify elec-
vice versa. Consequently, small interfering RNA (siRNA) could be loaded trical properties of samples.
and released in an acidic pH environment, enabling the hybrid particles and
their payload to avoid endosomal sequestration and enzymatic degradation. Results: Interfacial polymerization approach of fabricating conductive hy-
These nanoparticles loaded with specific siRNA molecules directed towards drogels provides marked improvement over the conventional approach
the transcript of the membrane receptor CXCR4 significantly decreased the of forming conductive hydrogels by mixing conductive particles within
expression of this protein in the human breast cancer cell line MDA-MB-231. hydrogel matrix. Based on the swelling, compression and biocompatibility
In addition, when siRNA-loaded nanoparticles were administered in vivo by testing, the Pegda/Gelma-Pani composites are similar in properties to the
intravenous injection in orthotopic mouse models of human breast cancer, pure biomimetic hydrogels, and therefore closer to the properties of in vivo
they preferentially accumulated in the tumor where they efficiently silenced extracellular matrix. This means that although more electro-conductive as
CXCR4. A full characterization of the response of endothelial cells to the compared to other biomaterials, hydrogel-Pani composites would elicit cel-
endolysosomal escape showed that pH-responsive nanoparticles transiently lular responses similar to pure Gelma and other biomaterials of similar prop-
affected key physiological cellular functions, such as the formation of cap- erties, and would serve as a suitable conductive scaffold. The presence of
illary-like structures on matrigel. A full biomolecular analysis implemented Pani within Pegda/Gelma matrix was verified using FTIR. Electrical properties
with confocal microscopy was performed to understand the nature of this of Gelma and Gelma-Pani samples were evaluated using Electrochemical
effect and discovered that the nanoparticles dispersed in the cytoplasm Impedance Spectroscopy (EIS) and a custom-made resistance-test-chip. EIS
interfered with the physiological rearrangement of the actin structure. In results were plotted in the form of Nyquist and Bode Plots and fitted with a
response to the damages caused by the escape from the endolysosomal standard Randles cell (RC) equivalent circuit model. Compared to pure Peg-
compartment, the cells produced multilaminar bodies surrounding and da/Gelma, Pani composite samples exhibited lower impedance especially
engulfing back the nanoparticles. The vesicles were able to first isolate the at physiologically-relevant low frequencies. Custom-made resistance testing
escaped nanoparticles from the other cellular compartments and then to chip also demonstrated a significant increase in conductivity for the Pegda/
clean the cytoplasm through exocytosis of the vesicles. In conclusion, the Gelma-Pani samples as compare to pure hydrogel controls. We also demon-
cytoplasmic dispersion of nanoparticulate can reveal some effects on cellu- strate that Pegda/Gelma-Pani composites with user-defined patterns can
lar physiological function, even though our data demonstrate that, at least in be fabricated. We used digital stereolithography to demonstrate that Gel-
vitro, they are transient due to the natural ability of the cells to recover from ma-Pani composite can be fabricated in complex user-defined geometries.
this kind of stress. This work can be potentially extended to fabricating variety of complex ge-
ometries using several photosensitive biopolymers for developing next-gen-
12:10pm Synthesis, fabrication and characterization of biocom- eration electrical biointerfaces.
patible conductive hydrogel composites
12:30pm Dissecting the Cell-Nanoneedle Interface to Elucidate
Technical Presentation. NEMB2016-6137 Intracellular Delivery of Payloads

Pranav Soman, Ping Dong, Yibo Wu, Syracuse University, Syra- Technical Presentation. NEMB2016-6056
cuse, NY, United States
Jonathan Martinez, Houston Methodist Research Institute, Hous-
Significance: Electrically conductive hydrogels have recently generated ton, TX, United States, Ciro Chiappini, Imperial College London,
much attention, as they have significant potential to serve as bioactive London, United Kingdom, Enrica De Rosa, Xuewu Liu, Houston
scaffolds with the ability to electrically stimulate cells and modulate their Methodist Research Institute, Houston, TX, United States, Molly M.
functions. These smart materials not only possess the unique properties of Stevens, Imperial College London, London, United Kingdom, Ennio
hydrogels such as tissue-like mechanical properties, high water content and Tasciotti, The Methodist Hospital Research Institute, Houston, TX,
good biocompatibility, but also possess the properties of electrically con-
ductive materials. However, one challenge still faced by nearly all electrically United States
conductive hydrogels is their low processability, which limit their applications
in tissue engineering and other biomedical engineering fields. In this work, Nanowire and nanoneedle-based approaches provide a facilitated access
we present the synthesis and fabrication of new conductive hydrogels by to the cytosol of the cell, and are able to interact with the intracellular envi-
combining intrinsically conductive polyaniline (Pani) within two hydrogel ronment by sensing their surrounding, capturing molecules and metabolites,
matrices, namely poly (ethylene glycol) diacrylate (Pegda) and gelatin meth- transferring a payload or recording the electrical activity. However, the
acrylate (Gelma) hydrogel. mechanism by which these materials achieve or induce cytosolic delivery
(i.e., nanoinjection) remains unclear. Current evidence suggests that nanon- 55
Methods: In this work, we synthesize photosensitive Pegda and Gelma eedles do not completely cross the plasma membrane but may only be
hydrogels using established protocols. Pegda or Gelma precursor solution tightly associated with its outer face. Hence, how cells and tissue respond