Carbon-nanotube reinforcement of DNA-silica nanocomposites yields programmable and cell-instructive biocoatings

Abstract

Biomedical applications require substrata that allow for the grafting, colonization and control of eukaryotic cells. Currently available materials are often limited by insufficient possibilities for the integration of biological functions and means for tuning the mechanical properties. We report on tailorable nanocomposite materials in which silica nanoparticles are interwoven with carbon nanotubes by DNA polymerization. The modular, well controllable and scalable synthesis yields materials whose composition can be gradually adjusted to produce synergistic, non-linear mechanical stiffness and viscosity properties. The materials were exploited as substrata that outperform conventional culture surfaces in the ability to control cellular adhesion, proliferation and transmigration through the hydrogel matrix. The composite materials also enable the construction of layered cell architectures, the expansion of embryonic stem cells by simplified cultivation methods and the on-demand release of uniformly sized stem cell spheroids.

Cultivation of Exoelectrogenic Bacteria in Conductive DNA Nanocomposite Hydrogels Yields a Programmable Biohybrid Materials System

“…As a potential candidate for an improved interface between electronics and microbiology, we chose a hierarchically structured porous 3D nanocomposite hydrogel comprised of SiNP, CNT and DNA strands. As previously reported 17 , this material is produced from DNA-coated SiNP and CNT particles that are interwoven with each other by enzymatic polymerization using the Phi29 DNA polymerase-catalyzed rolling circle amplification (RCA, see Fig 1a). For this purpose, SiNP (approx.…”

“…Synthesis of SiNP, chemical conjugation of SiNP and CNT with DNA oligonucleotide primers, ligation of rolling circle amplification (RCA) template (T) on SiNP-primer (CNT-P) and CNTprimer (CNT-P) and RCA polymerization of the nanoparticles were performed as previously described. 17 In brief, linear ssDNA (T, 10 µM, 30 µL) and 10X T4 DNA ligation buffer (500 mM Tris-HCl, 100 mM MgCl2, 10 mM ATP, 100 mM dithiothreitol (DTT), 7.5 µL) were added to 60 μL SiNP-P suspension (10 mg/mL) or CNT-P-T (800 µg/mL), followed by addition of T4 DNA ligase (400,000 U/mL, 2.5 µL, New England Biolabs) to ligate the nicked ends of the T oligonucleotide at 25 °C for 3 h. To synthesize SiNP/CNT-DNA hydrogels, the so-produced SiNP-P-T (50 µL) or CNT-P-T (50 µL) were then polymerized via RCA by mixing with dNTPs (10 mM, 10 µL), 10X BSA (10 mg/mL, 5 µL), 10X phi29 DNA polymerase buffer (500 mM Tris-HCl, 100 mM MgCl2, 100 mM (NH4)2SO4, 40 mM DTT, pH 7.5, 5 µL) and phi29 DNA polymerase (10,000 U/mL, 5 µL, New England Biolabs) at 30 °C for 48 h. Additional details on chemicals and oligonucleotide sequences (Table S1) are specified in the Supplementary Information.…”

“…Based on recent work on the application of porous nanocomposite materials accessible by DNA polymerization of CNT and silica nanoparticles (SiNP) as bioinductive coatings for eukaryotic cells, 17 we report here on the use of these materials for the construction of a programmable biohybrid system. To this end, we initially demonstrate electrical conductivity of the CNTcontaining composite by employment of chronopotentiometry (CP), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV).…”

Designer DNA–silica/carbon nanotube nanocomposites for traceable and targeted drug delivery

“…Preparation of SiNP/CNT-DNA nanocomposite materials Two different types of DNA nanocomposites, binary S and ternary SC materials were prepared by using SiNP (diameter 80 nm) 21 and CNT (diameter 0.83 nm, length 1 mm, Sigma-Aldrich) according to previously reported procedures. 12 Briefly, the linear ssDNA (T) phosphorylated at the 5 0 end was circularized through hybridization with P1 attached on the surface of SiNP-P using T4 DNA ligase. To this end, linear ssDNA (T, 10 mM, 30 mL) and 10Â T4 DNA ligation buffer (500 mM Tris-HCl, 100 mM MgCl2, 10 mM ATP, 100 mM dithiothreitol (DTT), 7.5 mL) were added to 60 mL SiNP-P suspension (10 mg mL À1 ), and the mixture was incubated at 25 1C for 3 h. After addition of 2.5 mL T4 DNA ligase (400 000 U mL À1 , New England Biolabs), the mixture was further incubated for more than 3 h at 25 1C to ligate the nicked ends of the template, leading to the formation of particle-primer-template (SiNP-P-T) complexes.…”

“…10 Furthermore, DNA hydrogel composites containing silica nanoparticles (SiNP) have recently been used for the bottom-up assembly of hollow spherical microstructures 11 and SiNP/CNT-DNA composites were used as programmable and cell-instructive biocoatings. 12 While in the latter work the outstanding attractiveness of SiNP-DNA materials for cells was used for the adjustable adhesion of eukaryotic cells, previous work has already shown that DNA-functionalized SiNP are not only highly biocompatible but are also very efficiently ingested by cells. 13 This work also showed that dye-labelled SiNP are excellently suited for traceable studies of the underlying biological mechanisms.…”