Two self-assembling twin guanine-cytosine (G∧C) hybrid molecules featuring porphyrin (TPPO-(G∧C)2) and oligothiophene groups (6T-(G∧C)2) were synthesized. In organic solution, these molecules self-assemble into one-dimensional rosette nanotubes (RNTs) featuring the porphyrin or oligiothiophene groups on the outer surface. Using a combination of imaging and spectroscopic techniques we established the structure of the TPPO-(G∧C)2 and 6T-(G∧C)2 RNTs and compared the HOMO and LUMO energy levels with PC61BM, a well-known electron acceptor material. These studies, in combination with solid-state photoluminescence data of PC61BM-TPPO-(G∧C)2 RNT blended thin films, indicates that these self-assembled nanomaterials have great potential as electron donor materials for solution-processed organic photovoltaics.

Rosette nanotubes (RNTs) are tubular architectures generated through the hierarchical self-assembly of the guanine-cytosine (G∧C) motif 1 or 2 (Figure 1). Motif 2 differs from 1 by the substitution at the N-atom in the G-ring with a C-atom as shown in red. In this paper, we prepare a new tricyclic G∧C base 3 from a functionalized derivative of 2 and demonstrate its self-assembly into fluorescent helical RNTs in N,N-dimethylformamide (DMF). The self-assembly and fluorescent properties of RNTs 3 were established using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV-visible spectroscopy.

With multifunctionality and nanoscale dimensions, self-assembled rosette nanotubes (RNTs) exhibit unique biological and mechanical properties, making them promising to serve as a new generation of implants. Synthetic twin G^C base features the hydrogen bonding arrays of both guanine and cytosine and has the ability to self-organize spontaneously into nanotubes with a 3.5 nm outer diameter, a 1.1 nm inner channel running the length of the nanotube which can reach several micrometers in length. In this study, a twin G^C motif functionalized with an aminobutyl side chain (referred to as TBL) was synthesized, assembled into bioactive RNTs and used along with poly(2-hydroxyethyl methacrylate) (pHEMA) and hydroxyapatite (HA) nanoparticles to prepare RNTs/HA/pHEMA composites for orthopedic applications. The properties of these composites was investigated, notably the solidification process, surface morphology, mechanical properties, and cytocompatibility properties. The RNTs assembled from TBL and HA nanoparticles were found to be effective towards increasing the bioactivity of the composites thus establishing the potential of TBL/HA/pHEMA composites as very promising injectable orthopedic implant materials.

Bone fractures are one of the most common bone complications. In more severe cases, bone fixation is accomplished using titanium (Ti) implant materials. Unfortunately, the need for revision surgery often arises due to implant loosening and/or deterioration of the implant/bone interface. Rosette nanotubes (RNTs) are a class of self-assembled organic materials obtained through the self-assembly of a guanine-cytosine hybrid base (G∧C motif). These organic materials have been found to increase osteoblast (bone forming cells) adhesion and hydroxyapatite deposition (bone regeneration) on titanium implants as well as on engineered hydrogels. In order to increase the bioactivity of RNTs to enhance bone cell function on Ti implants, two RNT motifs functionalized with different bioactive deca-peptides (A, B) chosen from the knuckle region of bone morphogenic proteins-7 (BMP-7) were synthesized. Their self-assembly process was investigated in water using UV-Vis and SEM techniques.

Electroless synthesis and hierarchical organization of 1.4 nm Pd and Pt nanoparticles (NPs) on self-assembled Rosette Nanotubes (RNTs) is described. The nucleated NPs are nearly monodisperse and reveal supramolecular organizations guided by RNT templates. Interestingly, the narrow size distribution is attributable to unique templating behavior of RNTs. The resulting metal NP-RNT composites were characterized by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). X-ray Photoelectron Spectroscopy (XPS) was also performed to confirm the nature and composition of RNT-templated NPs.

Discrete nanoscale tubular architectures have received significant attention during the past decade because of their potential role in electronic and photonic devices, sensors, liquid crystals, artificial channel systems and biomedical engineering [1-2]. Our research group has reported the synthesis and characterization of the bicyclic G∧C motif, a self complementary DNA base analogue, which undergoes hierarchical self-assembly to form Rosette Nanotubes (RNTs) [3]. The stability of this system depends however, on functional group density (sterics) and net charge (electrostatics) on the RNT surface [5c]. To this end, we have synthesized several G∧C modules bearing oligopeptides with different lengths and net charge and investigated their self-assembling properties.

A process optimization has been developed for obtaining nanocrystalline cellulose (NCC) by acid hydrolysis of commercially available microcrystalline cellulose (MCC) in high yield (~ 40-50%). This method was based on control of key parameters such as the rate of addition of sulfuric acid solution to the MCC/water suspension, the mixing speed, the volume of collected NCC suspensions and the volume ratio of NCC suspension to water during dialysis. The resulting NCC products were characterized by x-ray diffraction (XRD), thermogravimetric analysis (TGA), elemental analysis (EA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Electron microscopy results showed that the rod-shaped NCC had lengths and widths of about 40-400 nm and 5-40 nm, respectively.

Cationic rosette nanotubes (RNTs) were generated by functionalization of selfcomplementary twin guanine-cytosine (G^C) motifs with up to 15 L-lysine residues (Kn.T, n = 1–15). siRNA binding capacity was determined by gel retardation assay on agarose gel. Up to K5.T, siRNA complexation was a function of oligolysine-chain length and mole ratio of Kn.T. At higher Kn.T, local cationic density employed by supramolecular assembly emerged as a contributor to siRNA complexation. We have shown that no effective siRNA binding was achieved with equivalent mole ratios of corresponding oligolysine peptides (not conjugated to the G∧C motif). With K12.T, siRNA complexation gave spherical structures in the range of 200 nm, which was internalized and retained by human cell lines without noticeable cytotoxicity. In this report, we demonstrate for the first time the capacity of the RNTs as siRNA carriers that can be tailored to achieve maximum siRNA loading efficiency without carrier-associated cell toxicity. We anticipate these cationic RNTs to be effective in the delivery of biologicallyfunctional siRNA.

The synthesis and self-assembly of a water-soluble, tricyclic, self-complementary heterocycle that features the hydrogen bond donor-acceptor arrays of both guanine (G) and cytosine (C) juxtaposed between a pyridine ring is presented. In solution, this tricycle, which has been termed xK1, self-assembles into Rosette Nanotubes (RNTs) that have an inner diameter of 1.4 nm. Unlike the RNTs formed from the bicyclic congener K1, we demonstrate that xK1 with its extended ð system, forms a J-type RNT assembly determined through UV-Vis, CD and fluorescence spectroscopy experiments. This observation brings the possibility of developing electrically conducting RNTs for applications in the areas of photovoltaics and molecular wires.

We report preliminary studies on the preparation of carbon nanoparticles (CNPs) of ~ 20 nm in diameter derived from asphaltenes under mild conditions. This transformation occurred upon heating a thin film of asphaltenes cast on a carbon coated copper grid under both nitrogen and oxygen atmosphere. The resulting CNPs were characterized by thermogravimetric analysis (TGA), scanning/transmission electron microscopy (SEM/STEM), transmission electron microscopy (TEM), elemental analysis (EA) and Auger electron spectroscopy (AES). The findings point towards asphaltenes, a crude oil by-product, as a potential source for carbon nanomaterials.

Rosette nanotubes (RNTs) are obtained through the self-organization of biologically inspired self-complementary guanine-cytosine modules (G∧C motif) under physiological conditions. These architectures can express bioactive molecules on their surface by functionalizing the G∧C motif prior to self-assembly. As a result, RNTs are promising drug delivery vehicles for the treatment of diseases such as cancer and inflammatory disorders. Towards these studies, we have explored the toxicity and immunological response of RNTs and are now focused on understanding their cellular uptake, biological distribution and kinetics in vivo. For these investigations, we need to construct a RNT labeled with a radionuclide that can be followed in vivo by SPECT (single photon emission computed tomography) imaging. In this proceeding, we describe a twin G∧C motif that is functionalized with mercaptoacetyl triglycine (MAG3). This is a well known ligand which is able to form a stable chelate with the radionuclides 99mTc or 186/188Re. In order to develop the chemistry for this radiolabeling strategy for the RNTs, we demonstrate the chelation of the MAG3 functionalized twin-G∧C motif with cold rhenium and investigate the self-assembly properties of the complex into RNTs under aqueous conditions.

Rosette nanotubes (RNTs) are novel, biomimetic, synthetic, self-assembled drug delivery agents. Because of base stacking and hydrophobic interactions, the RNT hollow-tube structure can be used for incorporating drugs. Another advantage of using RNTs is their ability to be injected and become solid at body temperatures for orthopedic applications without the use of any external stimuli (such as UV light or crosslinking agents). The nano-features of RNTs create a favorable, biologically-inspired, cellular environment. In this study, methods to incorporate dexamethasone (DEX, a bone growth promoting drug) into RNTs were investigated. The drug-loaded RNTs were characterized using Nuclear Magnetic Resonance (NMR), Diffusion Ordered Spectroscopy (DOSY) and Ultraviolet-visible Spectroscopy (UV-vis). Results showed that small molecular drugs with hydrophobic aromatic rings were incorporated into RNTs. Subsequent drug release experiments demonstrated that DEX was released from the RNTs and had a positive impact on osteoblast functions. Importantly, compared to other drug carriers, RNTs increased the total drug loading and was the highest when DEX was incorporated during the RNT self-assembly process. Thus, this study offered a novel drug delivery device that itself is bioactive and can be used to deliver a variety of drugs for various orthopedic applications.

Various bone defects, caused by trauma, disease or age-related degeneration, represent a crucial clinical problem all over the world. However, traditional implant materials may cause many complications after surgeries, leading to intense patient pain. Thus, the objective of this in vitro study was to develop a biologically inspired coating on conventional titanium with materials that possess biomimetic nanostructured architectures and favorable surface chemistry. Specifically, self-assembled rosette nanotubes (RNTs) functionalized with various osteogenic peptides and amino acids (such as lysine-arginine-serine-arginine (KRSR), arginine-glycine-aspartic acid (RGD) and lysine (K)) were designed as coatings. Results revealed excellent cytocompatibility properties of these RNTs towards enhancing osteoblast (bone forming cell) and endothelial cell adhesion. In particular, KRSR and RGD functionalized RNTs coated on titanium promoted the greatest osteoblast densities when compared to uncoated titanium. In addition, the KRSR functionalized RNTs selectively improved osteoblast adhesion but not endothelial cell adhesion when coated on titanium. From this study, it can be speculated that the biologically inspired nanotubular structure and osteogenic surface chemistry of RNTs altered the surface properties of titanium to transform it into a more favorable environment for orthopedic applications.

The current clinical treatment of cartilage defects involves autologous chondrocyte implantation into cartilage defect sites. However, one of the complications associated with this method is the lack of bonding between the implanted materials and natural tissue. Helical rosette nanotubes (HRNs) are novel biomimetic self-assembled supramolecular structures whose basic building blocks are DNA base-pairs. HRNs are similar in size to collagen in cartilage. Moreover, previous studies have shown that HRNs are biocompatible and increase the adhesion of numerous cells compared to other commonly used cartilage implant materials (like hydrogels and Ti). In addition, HRNs can solidify into a viscous gel at body temperatures under short periods of time. Thus, it is hoped that HRNs can serve as a novel in situ tissue implant to improve cartilage cell adhesion and functions. In this study, in order to heal cartilage rupture and regenerate cartilage during possible implantation, the mechanical properties of select hydrogel/HRN composites were tested. In addition, electro-spinning was used to generate three-dimensional, implantable, composite fibers encapsulated with chondrocytes and fibroblast-like type-B synoviocytes (SFB cells, a type of mesenchymal stem cell). Importantly, results showed that drug-delivered HRNs enhanced hydrogel adhesive strength and created a scaffold with nanometer-rough surface structures pertinent for cartilage regeneration. In this manner, this study provided an alternative cartilage regenerative material which relies on nanotechnology that can be injected as a liquid, solidify at body temperatures under short periods of time, have suitable mechanical properties to collagen, and promote cell functions.

Rosette Nanotubes (RNTs) are formed by the self-assembly of a guanine-cytosine motif (GΛC), a hybrid of the DNA bases guanine and cytosine, to give a six membered macrocycle maintained by 18 H-bonds. In theory, any moiety covalently attached to the GΛC base can be expressed on the nanotubes surface. However we anticipate that the self-assembly and stability of these functionalised RNTs will also be governed by steric effects. Herein we describe the synthesis and the self assembly of the Twin Base Lysine (TBL-K) and its monobase (MBL-K). While TBL-K self-assembles readily in water and methanol to give nanotubular structures, MBL-K does not form nanotubes. Various techniques were used to characterize the RNTs and the factors, preventing self-assembly in the case of MBL-K, were investigated.

Rosette nanotubes (RNTs) were used as structure-directing agents for the synthesis of microporous and/or mesoporous silica nanotubes. The silica nanomaterials were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and CO2 and nitrogen physisorptions. The results show that the mode of the obtained porous systems as well as the surface areas and volume of micro- and/or mesopores depend on the nature of the pendant attached to the rosette nanotubes surface.

The self-assembly of six self-complimentary Guanine – Cytosine hybrid heterocycles bearing hydrophobic substituents has been studied using combinatorial approach in eight solvents under different conditions. The parameters that were varied include: the structure of the self-assembling module, its concentration, the solvent, temperature, and time of self-assembly. scanning electron microscopy (SEM) was used as a screening tool. A wide variety of interesting morphologies was found. The most interesting structures were studied by atomic force microscopy (AFM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray powder diffraction (XRD).

Random bead microarray in which each bead has been functionalized with different biomolecules are of great interest. The process by which one would identify the location of each bead is referred to as decoding. The decoding step has played a challenging role in microarray technologies due to the increase in complexity with the increase in array size. Here we report a novel, fast and reliable method of decoding randomly assembled arrays based on polymer beads with unique spectroscopic signatures. Beads were synthesized by dispersion polymerization of a family of styrene monomers and methacrylic acid to generate a spectroscopically encoded bead library. In addition to identifying the self-encoded beads through their unique spectrum in a tetraplex experiment, Raman spectroscopy was used to monitor antibody-antigen binding events on the barcoded beads. The simplicity, versatility and rapid analysis enabled by this self-encoded bead array platform technology demonstrates its potential in high-throughput biomolecular multiplex screening.

To date, although traditional autografts and allografts have been standard methods to treat bone fractures and defects, the formation of biocompatible and injectable scaffolds to induce new bone growth is still a promising method to repair bone defects considering their minimally invasive and osteoinductive features. In this study, a novel bone tissue engineering scaffold based on the self-assembled properties of helical rosette nanotubes (HRNs) and biocompatible hydrogels (specifically, poly(2-hydroxyethyl methacrylate)-pHEMA) was designed to fill bone fractures and repair bone defects. HRNs are a new class of organic nanotubes with a hollow core 11 Å in diameter, which originate from the self-assembly of DNA base pair building blocks (guanine-cytosine) in aqueous solutions. Since HRNs can significantly change their aggregation state and become more viscous based on heating or when added to serum free medium at body temperature, HRNs may provide an exciting therapy to heal bone fractures as injectable bone substitutes. In addition, biocompatible hydrogels were used in conjunction with HRNs in this study to strengthen the bone substitutes and also to serve as a potential drug releasing carrier to stimulate new bone growth at such fracture sites. Two types of HRNs, one with a lysine side chain and the other conjugated to 1% and 10% RGD (arginine-glycine-aspartic acid) peptides on HRNs, were prepared and dispersed into hydrogels. Due to their nanometric features and the helical architecture of HRNs which biomimic collagen, results showed that these HRN hydrogel composites can significantly improve osteoblast adhesion compared to hydrogel controls. Furthermore, 0.01 mg/ml HRNs with RGD embedded in and coated on hydrogels can also enhance osteoblast attachment compared to 0.01 mg/ml HRNs with lysine side chains embedded in and coated on hydrogels. Results showed an increasing trend of osteoblast adhesion on these scaffolds with more RGD groups (10%) on HRNs. In this manner, nanostructured HRN hydrogel composites provide a promising alternative to repair bone defects considering the flexibility in the design of HRNs and their exceptional cytocompatibilty properties.