Functionalization Of Single-walled Carbon Nanotubes Research Articles

Enhanced cellular internalization of near-infrared fluorescent single-walled carbon nanotubes facilitated by a transfection reagent

Functionalized single-walled carbon nanotubes (SWCNTs) hold immense potential for diverse biomedical applications due to their biocompatibility and optical properties, including near-infrared fluorescence. Specifically, SWCNTs have been utilized to target cells as a vehicle for drug delivery and gene therapy, and as sensors for various intracellular biomarkers. While the main internalization route of SWCNTs into cells is endocytosis, methods for enhancing the cellular uptake of SWCNTs are of great importance. In this research, we demonstrate the use of a transfecting reagent for promoting cell internalization of functionalized SWCNTs. We explore different types of SWCNT functionalization, namely single-stranded DNA (ssDNA) or polyethylene glycol (PEG)-lipids, and two different cell types, embryonic kidney cells and adenocarcinoma cells. We show that internalizing PEGylated functionalized SWCNTs is enhanced in the presence of the transfecting reagent, where the effect is more pronounced for negatively charged PEG-lipid. However, ssDNA-SWCNTs tend to form aggregates in the presence of the transfecting reagent, rendering it unsuitable for promoting internalization. For all cases, cellular uptake is visualized by near-infrared fluorescence microscopy, showing that the SWCNTs are typically localized within the lysosome. Generally, cellular internalization was higher in the adenocarcinoma cells, thereby paving new avenues for drug delivery and sensing in malignant cells.

Process controlled microstructure of polyvinylidene fluoride/functionalized single walled carbon nanotube composites

AbstractPolyvinylidene fluoride (PVDF)‐functionalized single walled carbon nanotube (FSWCNT) film composites were prepared by two different process conditions—air drying and vacuum drying. Though reports on –PVDF‐FSWCNT composites are available, we provide a new outlook here, which is based on optimized functionalization and novel processing conditions. The microstructural and phase changes occurring in PVDF having nanotubes functionalized for different extent of time were investigated and confirmed that those functionalized for 4 h (FSWCNAT‐4) create polar γ phase in PVDF with improved mechanical and electrical properties. X‐ray photoelectron spectroscopy studies showed that PVDF/FSWCNT‐4 composites have the maximum percentage of functional groups. It is also found that PVDF/FSWCNT‐4 composite films prepared through air drying were rough and had a cloudy appearance suitable for applications demanding open porous structures, whereas those prepared through vacuum drying process were smooth and homogeneous with high optical transparency, suitable for microelectronic applications. Thus, by suitably controlling the processing conditions and by using optimally functionalized nanotubes, PVDF films with multifunctional properties could be achieved. In order to extract the full capabilities of PVDF/SWCNT films, functionalization of the nanotube together with processing conditions plays a significant role.

Microwave-Assisted Functionalization of Single-Walled Carbon Nanotubes as a Platform for a Supported Iridium Catalyst

AbstractSingle-walled carbon nanotubes (SWCNTs) were functionalized by treatment with imino esters through 1,3-dipolar cycloaddition activated by thermal 1,2-prototropy. The reaction was optimized and analyzed by using various heating methods. The functionalization afforded pyrrolidino-functionalized nanotubes that were characterized by using several techniques. The ester group was then transformed into the corresponding SWCNT–iridium carboxylate and, as a proof of concept, the product was tested as a catalyst in the hydrogen-transfer reaction of acetophenone to yield 1-phenylethanol.

Electrochemically Functionalized Single-Walled Carbon Nanotubes With Polypyrrole for the Detection of Sub-Part-per-Million Concentrations of Ammonia

Here we report a facile method of functionalization of single-walled carbon nanotubes (SWNTs) with polypyrrole and making a chemiresistive sensor using the functionalized nanomaterial for sub-part-per-million detection of ammonia gas at room temperature. The sensor fabrication involves three steps: (i) immobilization of SWNTs by dip coating method on a silane-treated silicon/silicon dioxide substrate, (ii) printing of two parallel lines of conducting silver paste 5 mm apart as source and drain to define the source and the drain electrode, and (iii) in-situ electrochemical polymerization to functionalize the SWNTs with polypyrrole. The functionalization of SWNT was confirmed using electrochemical current-voltage measurements. The functionalized SWNTs exhibited several folds higher sensitivity to ammonia gas than the pristine SWNTs. A charge density of 0.85 C.cm−2 was optimum for electrochemical functionalization, providing maximum sensing response toward ammonia. The functionalized SWNTs showed a large measurable response starting from 50 to 750 part-per-billion (ppb) of ammonia with a sensitivity of ∼1.55% per ppb, and a limit of detection of 5 ppb of ammonia. Almost complete recovery of the sensor and an average response time of ∼9 min was also observed.

Near-infrared photoluminescent detection of serum albumin using single-walled carbon nanotubes locally functionalized with a long-chain fatty acid

Serum albumin (SA) is a protein found in biofluids that is useful for diagnosing kidney and liver-related diseases. Single-walled carbon nanotubes (SWCNTs) showing photoluminescence (PL) in the near-infrared (NIR) region are prospective candidates for diagnosis NIR probes. Their NIR PL enhancement has been reported by defect introduction techniques based on local chemical functionalization of SWCNTs. The locally functionalized (lf-)SWCNTs exhibit a bright defect PL (>1000 nm) from the defect sites and its sensitive wavelength shifts in response to surrounding dielectric atmospheres have been reported. Here, we used the sensitive defect PL responses of lf-SWCNTs to establish a NIR sensing system for SA detection. A palmitic acid group that binds to SA strongly and selectively, was functionalized at the defect site of lf-SWCNTs (lf-SWCNTs-p). Compared to typical PL of unmodified SWCNTs, selective defect PL red-shifts (of 2.5 nm max.) were clearly observed according to the addition of SA in phosphate-buffered saline. The defect PL responsiveness could detect different SA from human, bovine, and mouse. The red-shifts of the defect PL occurred by formation of a high dielectric environment based on the specific binding between SA and the palmitic acid groups on the defect sites. The lf-SWCNTs-p detected SA-spiked serum and albuminuria of diabetic mouse in body fluids. The findings show that the lf-SWCNTs-p offer an NIR PL analytical tool for SA in body fluids applicable to a disease diagnosis and expand the bioapplications of lf-SWCNTs based on their molecular design-based defect engineering.

(Invited) Microenvironment Responsiveness of Defect Photoluminescence of Locally Functionalized Single-Walled Carbon Nanotubes and Its Sensing Applications

Photoluminescence (PL) of single-walled carbon nanotubes (SWCNTs) in the near infrared (NIR) region is applicable to advanced optical applications such as bio-imaging and sensing. Local chemical functionalization (slight amount of chemical modification) of SWCNTs has been developed to introduce sp3 carbon defects in the sp2 carbon network of the tube walls for the luminescent defect formation.[1-3] The resultant locally functionalized SWCNTs (lf-SWCNTs) show defect PL (E 11* PL) with red-shifted wavelengths and increased quantum yields compared to original E 11 PL of pristine SWCNTs. For lf-SWCNTs, molecularly designed modifier molecules have enabled the defect PL wavelength modulation[4] and the sensing function creation.[5,6]Recently, we have reported the unique microenvironment responsiveness of defect PL of lf-SWCNTs; namely, the greater wavelength shifts of E 11* PL than E 11 PL by dielectric effects[7] and the PL shifting behavior modulation based on the chemical structure difference of the functionalized sites and the exciton localization effects[8] were observed. The microenvironment responsiveness of the defect PL was applied to the biological sensing application development.[9] To investigate protein detection/recognition functions of lf-SWCNTs, we introduced an avidin-biotin interaction with a selective and strong binding fashion at the functionalized sites of lf-SWCNTs. The lf-SWCNTs tethering biotin groups (lf-SWCNTs-b) were synthesized through diazonium chemistry, followed by its subsequent-modification. When neutravidin was mixed with a lf-SWCNTs-b solution, E 11* PL peak was red-shifted, indicating the higher polarity environment formation by the neutravidin adsorption on lf-SWCNTs-b. When avidin or streptavidin was used, wavelength shifting behaviors of E 11* PL of lf-SWCNTs-b were clearly changed depending on the used avidin derivatives. The results indicate the different polarity environment formation deriving from structural differences of each avidin derivative. Moreover, the detection signal enhancement was observed in a film device using lf-SWCNTs-b. Therefore, lf-SWCNTs have a high potential for development of advanced protein detection/recognition systems using NIR PL.[1] T. Shiraki et al. Acc. Chem. Res., 53, 1846 (2020). [2] S. Tretiak et al., Acc. Chem. Res., 53, 1791(2020) [3] Y. Wang et al. Nat. Rev. Chem., 3, 375 (2019). [4] T. Shiraki et al. ACS Nano, DOI: 10.1021/acsnano.2c09897 (2022). [5] T. Shiraki et al. Chem. Commun., 52, 12972 (2016). [6] S. Kruss et al, Angew. Chem. Int. Ed., 59, 17732 (2020). [7] T. Shiraki et al. Chem. Commun., 55, 3662 (2019). [8] T. Shiraki et al. J. Phys. Chem. C, 125, 12758 (2021). [9] T. Shiraki et al. Nanoscale, 14, 13090 (2022). Figure 1

Guanine Functionalization of SWCNTs Using Metalloporphyrin Photosensitizers

Chemical modifications of single-wall carbon nanotubes (SWCNT) have opened new areas in the creation of quantum defects and the tailoring of optical properties for these one-dimensional semiconducting materials. Recent research has revealed a novel and controllable chemical functionalization reaction in which guanine nucleobases of ssDNA coatings react covalently with the SWCNT side wall in the presence of singlet oxygen. Generation of singlet oxygen through photosensitizer optical excitation is a key part of this process. To further explore guanine functionalization of SWCNTs, we have investigated reaction kinetics under various conditions. We replaced the rose bengal photosensitizer by metalloporphyrin dyes. These have greater photostability and more intense and shorter wavelength absorptions, allowing them to be used at micro- to nanomolar concentrations and leaving a wider spectral transparency window for reaction monitoring. Excitation was at 405 nm. Our kinetic studies show that the rates of change of E11 and E22 energies depend linearly on sensitizer concentration, which implies that guanine functionalization is a first order reaction with respect to singlet oxygen. Using a series of oligos with the same length but different guanine contents, we find E11 spectral shifts that increase sub-linearly to an asymptotic value. To help understand the structure of the guanine covalent adduct, we also performed semi-empirical quantum chemistry simulations. These suggest that the lowest energy structure is bonded to two adjacent carbon atoms of the SWCNT sidewall, and that reaction exothermicity is larger for smaller diameter nanotubes. Computations will also be presented for presumed intermediate adducts of guanine peroxide bonded to (6,5) SWCNTs in different orientations relative to the nanotube axis.

Stepwise Functionalization of Single-Walled Carbon Nanotubes with Subsequent Molecular Conversion to Control Photoluminescence Properties.

Functionalization of single-walled carbon nanotubes (SWCNTs) has attracted interest because it alters the near-infrared (NIR) photoluminescence (PL) wavelength and emission efficiency. These modifications depend on the binding configuration and degree of functionalization. Excessive functionalization reduces the emission efficiency as the integrity of the conjugated π system decreases; thus, controlling the degree of functionalization is essential. Because the binding configurations and degree of functionalization are affected by the reagent structure, a stepwise approach combining SWCNTs functionalization and subsequent reactions to introduce functional groups into the addenda could effectively control their PL properties and functionalities. We studied this approach by implementing the reductive alkylation of SWCNTs by using bromoalkanes with t-butyl carbamate (Boc)-protected amino groups and subsequent deprotection and amidation reactions. The reaction products were analyzed based on absorption, PL, and Raman spectroscopy and the Kaiser test. Depending on the structure of the reagent, deprotection and amidation reactions competed with the elimination reaction of addenda, altering the PL properties of the SWCNTs. Furthermore, the elimination reaction was inhibited in the adducts functionalized using dibromoalkane with Boc-protected amino groups, demonstrating that the use of appropriate reagents enables the molecular conversion of the functional groups of SWCNT adducts without affecting their PL properties.

Controlling Near-Infrared Photoluminescence Properties of Single-Walled Carbon Nanotubes by Substituent Effect in Stepwise Chemical Functionalization

Introducing the quantum defects into single-walled carbon nanotubes (SWNTs) enhances their photoluminescence (PL) with red-shifted peaks; however, the precise control of the chemical modification and PL wavelength remains difficult. In this work, the stepwise chemical functionalization of SWNTs was shown to be useful for controlling site-specific functionalization and PL, experimentally and theoretically. Dialkylated and hydroalkylated SWNTs were selectively synthesized using alkyllithium reagents, bromoalkane, and trifluoroacetic acid. The nBu-SWNT-nBu and nBu-SWNT-H adducts of the (6,4), (6,5), (8,3), and (7,5) SWNTs that were separated using gel chromatography showed dominant E11** PL and E11* PL, respectively. The systematic assignments of the PL were performed based on the thermodynamic stability and transition energy of 1,2- and 1,4-adducts of SWNTs using density functional theory (DFT) and time-dependent DFT calculations. It was shown that the steric hindrance of the added group and the R value, that is, mod(n – m, 3) in an (n,m) chiral nanotube, are key factors that control the addition site and the magnitude of the local band gap.

Decatungstate‐Photocatalyzed Acylation of Single‐Walled Carbon Nanotubes

AbstractAlthough the functionalization and modification of single‐walled carbon nanotubes (SWCNTs) has been advanced for two decades, their chemical transformation via catalytic processes has yet to be explored and further facilitate their industrial utility. Here, the decatungstate‐photocatalyzed acylation is described of semiconducting (7,6)SWCNTs and the scope of the reaction is investigated by employing alkyl, aromatic, and organometallic aldehydes. The success of the methodology is confirmed by diverse spectroscopic, thermal, microscopy imaging, and redox techniques. The developed catalytic process for the functionalization of SWCNTs is environmetal friendly, since the catalyst and unreacted aldehydes can be recovered and reused, while the modified SWCNTs can be easily isolated and purified by membrane filtration. It is believed that the current findings will open new avenues for the catalytic functionalization of SWCNTs and the approach is intended to extend for modifying 2D nanomaterials.

Highly efficient SWCNT/GaAs van der Waals heterojunction solar cells enhanced by Nafion doping

The atomic-level interface and strong interfacial interaction enable van der Waals (vdW) heterostructures to fabricate innovative photovoltaic devices by combing single-walled carbon nanotubes (SWCNTs) with bulk semiconductors, in which the device performance can be enhanced significantly using outstanding photoelectric property of SWCNTs. Herein, we reported a facile method to fabricate SWCNT/GaAs vdW heterojunction solar cell by transferring p-type (6,5)-enriched SWCNT film onto the n-type GaAs substrate, a power conversion efficiency (PCE) of 7.23 % has been achieved without any other treatment. Furthermore, the PCE value can be enhanced to 11.24 % by introducing Nafion as a highly effective dopant with a short-circuit current density of 24.70 mA/cm2, an open-circuit voltage of 0.64 V and a fill factor of 0.71. Our results reveal that the introduction of Nafion not only induces a stronger and closer contact at the interface between SWCNTs and GaAs, but also shows strong p-doping effect due to the existence of sulfonic acid functional groups. This p-doping effect of Nafion increases the work function of SWCNTs and subsequently enlarges the barrier height at the heterojunction for more efficient carrier separation. In addition, Nafion can also serve as an antireflection and passivation layer, reducing the incident light loss and the carrier recombination rate. These findings suggest that Nafion could be used to improve the performance of SWCNT-based vdW heterojunction devices.

Carbon nanotube uptake in cyanobacteria for near-infrared imaging and enhanced bioelectricity generation in living photovoltaics.

The distinctive properties of single-walled carbon nanotubes (SWCNTs) have inspired the development of many novel applications in the field of cell nanobiotechnology. However, studies thus far have not explored the effect of SWCNT functionalization on transport across the cell walls of prokaryotes. We explore the uptake of SWCNTs in Gram-negative cyanobacteria and demonstrate a passive length-dependent and selective internalization of SWCNTs decorated with positively charged biomolecules. We show that lysozyme-coated SWCNTs spontaneously penetrate the cell walls of a unicellular strain and a multicellular strain. A custom-built spinning-disc confocal microscope was used to image the distinct near-infrared SWCNT fluorescence within the autofluorescent cells, revealing a highly inhomogeneous distribution of SWCNTs. Real-time near-infrared monitoring of cell growth and division reveal that the SWCNTs are inherited by daughter cells. Moreover, these nanobionic living cells retained photosynthetic activity and showed an improved photo-exoelectrogenicity when incorporated into bioelectrochemical devices.

Determination of activation energy for carbon/epoxy prepregs containing carbon nanotubes by differential scanning calorimetry

The aim of the present study is the thermal characterization of laboratory-scale carbon fiber/epoxy-based prepregs by incorporating single-wall carbon nanotubes (SWCNTs). Investigation of the cure behavior of a prepreg system is crucial for the characterization and optimization of the fiber reinforced polymeric (FRP) composite. To affect dispersion characteristics, SWCNTs were functionalized by oxidizing their surface with carboxyl (-COOH) group using an acid treatment. The modified resin system contained 0.05, 0.1, and 0.2 wt. % functionalized SWCNTs (F-SWCNTs). Carbon fiber (CF) reinforced prepregs containing various amount of F-SWCNTs were prepared using drum-type winding technique. FTIR was performed to identify new bonding groups formed after the functionalization of SWCNTs. Cure kinetics of prepregs prepared with/without F-SWCNTs were investigated using isoconversional methods.

(Digital Presentation) Excitonic Photoluminescence Properties of Locally Functionalized Single-Walled Carbon Nanotubes Using Molecular Modifiers

Excitons in single-walled carbon nanotubes (SWCNTs) show unique properties due to strong quantum confinement and weak dielectric screening effects which give rise to high binding energies based on strong Coulombic interactions. By this feature, stable and mobile excitons are generated in SWCNTs and its radiative recombination produces photoluminescence (PL) in the near infrared (NIR) region. Recently, local chemical functionalization of SWCNTs has attracted great attention because of enhancement of their NIR PL properties.[1-5] This functionalization dopes local defects such as sp3 carbon to the semiconducting sp2 carbon networks of SWCNTs based on the covalent bond formation between the tube walls and modifier molecules. As a result, emissive doped sites that have narrower band gaps and exciton trapping features are created in the locally functionalized SWCNTs (lf-SWCNTs). For lf-SWCNTs, E 11* PL newly appears with red-shifted wavelengths and increased PL quantum yields compared with original E 11 PL of pristine SWCNTs. Currently, chemical functionalization methods and E 11* PL wavelength modulation techniques are being developed for further functionalization of lf-SWCNTs. [1-5] In this presentation, E 11* PL properties of lf-SWCNTs synthesized using newly designed chemical modifiers are discussed. For example, an azide compound is found to produce the emissive doped sites in lf-SWCNTs via a [2+1] cycloaddition reaction. The E 11* PL peak was observed at 1118 nm and N1s peak in X-ray photoelectron spectroscopy was detected around 400 eV regions based on the chemical bond formation. Moreover, solvatochromic PL energy shifts of the E 11* PL showed a different trend from those observed for typical lf-SWCNTs synthesized using diazonium chemistry. This result indicates that the chemical structures of the doped sites could be a key factor to modulate excitonic properties of localized excitons in lf-SWCNTs. Therefore, the molecular chemistry approach would provide unique exciton engineering tools for lf-SWCNTs and develop advanced excitonic NIR materials applicable to quantum cryptography technologies and high-performance bio/medical imaging and sensing.[1] T. Shiraki, Chem. Lett., 50, 397 (2021); [2] T. Shiraki et al., Acc. Chem. Res., 53, 1846 (2020); [3] S. Tretiak et al., Acc. Chem. Res., 53, 1791 (2020); [4] Y. Wang et al., Nat. Rev. Chem., 3, 375 (2019); [5] J. Zaumseil, Adv. Optical Mater. 2101576 (2021).

(Invited, Digital Presentation) Ortho-Substituent Structure Design in Aryldiazonium Salts for Defect Photoluminescence Modulation of Locally Functionalized Single-Walled Carbon Nanotubes

Photoluminescence (PL) of single-walled carbon nanotubes (SWCNTs) appears in the near infrared (NIR) region, which is applicable to advanced optical applications such as bioimaging and telecommunication devices. Local chemical functionalization of SWCNTs has been gathering great attention because of the enhancement of their NIR PL properties. Therein, defects such as sp3 carbon are locally doped to the crystalline sp2 carbon network of the tube walls by the chemical functionalization process.[1-4] As a result, the locally functionalized SWCNTs (lf-SWCNTs) emit new PL with red-shifted wavelengths and increased quantum yields from the doped sites (E 11* PL) compared to original E 11 PL of pristine SWCNTs. It is due to the doping effects to change electronic structures for narrower bandgap formation, by which mobile excitons in the tubes are trapped at the doped sites to be localized states for efficient PL conversion.The chemical functionalization approach allows us to use various chemical reactants for the doped site formation in lf-SWCNTs. The molecular effects including structural differences and molecular binding functions have resulted in versatile NIR PL wavelength modulation of lf-SWCNTs.[1-4] We have reported that E 11* PL generation phenomena were significantly varied depending on isomeric structures of substituted aryldiazonium salts (AD) used for lf-SWCNT synthesis.[5] Especially, ortho-substituted ADs (oADs) produced two PL around 1100 and 1250 nm-regions, respectively for the resulting lf-SWCNTs with (6,5) chirality. Here, we apply various substituent design for oADs and examine the substituent structure effects in terms of modulation of the PL emission properties of lf-SWCNTs. For example, oAD having a phenyl substituent resulted in enhancement of the ~1250 nm PL contribution. Other substituent effects are observed depending on substituent structures of oADs, from which interactions between the substituents and the tubes are considered to induce the observed PL spectral changes. The result indicates that local chemical functionalization using oAD has a high potential to largely modulate NIR PL wavelengths of lf-SWCNTs beyond 1000 nm regions.[1] T. Shiraki et al. Acc. Chem. Res., 53, 1846 (2020). [2] S. Tretiak et al., Acc. Chem. Res., 53, 1791(2020) [3] Y. Wang et al. Nat. Rev. Chem., 3, 375 (2019). [4] T. Shiraki, Chem. Lett., 50, 397 (2021). [5] T. Shiraki et al. Chem. Commun., 53, 12544 (2017).

Improving Antibacterial Activity of Methicillin by Conjugation to Functionalized Single-Wall Carbon Nanotubes Against MRSA

Improving Antibacterial Activity of Methicillin by Conjugation to Functionalized Single-Wall Carbon Nanotubes Against MRSA

Imidazole functionalized graphene and carbon nanotubes for CO2 detection

The effect of the non-covalent functionalization of single-walled carbon nanotubes (SWNTs) and graphene with imidazole is evaluated using Density Functional Theory (DFT) with the aim of improving the CO2 detection. Both metallic and semi-conducting SWNTs are investigated. The interaction of imidazole ring with different carbon nanomaterials is analyzed, as well as the adsorption of CO2 before and after the surface functionalization process. The binding energies, the energy band gaps, the Fermi levels, and the charge transfer process have been computed for all the possible fragments and for the total interacting systems. The functionalization of SWNT(8,0) and graphene by an imidazole ring increases the stability of CO2 physisorption and improves the positive charge transfer from CO2 to the carbon material, confirming that such functionalization can be a viable strategy for CO2 detection.

Enhancing mechanical and interfacial properties of PEEK/epoxy/SWCNT composites employing aromatic hydroxyl and amine-functionalized SWCNTs

Employing epoxy polymer and pristine and aromatic amine and hydroxyl functionalized SWCNTs in poly(ether ether ketone) (PEEK), novel polymer nanocomposite models were created. Molecular dynamics (MD) simulations were used to explore the interfacial, mechanical, and structural features of single-walled carbon nanotube (SWCNT) reinforced PEEK/epoxy matrix (BM) systems. We used MD simulation techniques to show how covalently functionalizing SWCNTs and blending PEEK with a polymer containing hydroxy‑functional groups can improve the interfacial and mechanical properties of PEEK nanocomposites. This study showed that –CH2C6H4NH2, –CH2C6H4OH group grafted SWCNT improve the interfacial and mechanical properties of PEEK-based nanocomposites due to the formation of hydrogen bonds between the filler materials and the polymer matrix, as well as better filler dispersion into the polymer matrix. The improvement of properties of polymer nanocomposites depends on the extent of the interaction of nanoparticles with the polymer matrix. Aromatic amine and hydroxyl (-CH2C6H4NH2, and -CH2C6H4OH) functionalization of SWCNTs is required for their high-performance engineering applications. Because epoxy polymer has a great ability to form hydrogen bonds with fictionalized SWCNT, adding 10% epoxy polymer to the BM increased the interfacial strength, elastic modulus, and shear modulus of SWCNT composites. This study provides a novel technique to improve the properties of polymer nanocomposites by covalently functionalizing SWCNTs.

Quantum defects as versatile anchors for carbon nanotube functionalization.

Single-wall carbon nanotubes (SWCNTs) are used in diverse applications that require chemical tailoring of the SWCNT surface, including optical sensing, imaging, targeted drug delivery and single-photon generation. SWCNTs have been noncovalently modified with (bio)polymers to preserve their intrinsic near-infrared fluorescence. However, demanding applications (e.g., requiring stability in biological fluids) would benefit from a stable covalent linkage between the SWCNT and the functional unit (e.g., antibody, fluorophore, drug). Here we present how to use diazonium salt chemistry to introduce sp3 quantum defects in the SWCNT carbon lattice to serve as handles for conjugation while preserving near-infrared fluorescence. In this protocol, we describe the straightforward, stable (covalent), highly versatile and scalable functionalization of SWCNTs with biomolecules such as peptides and proteins to yield near-infrared fluorescent SWCNT bioconjugates. We provide a step-by-step procedure covering SWCNT dispersion, quantum defect incorporation, bioconjugation, in situ peptide synthesis on SWCNTs, and characterization, which can be completed in 5-7 d.

Physical Characterization and Material Properties of Epoxy Matrix Nanocomposites Containing Functionalized Single-Walled Carbon Nanotubes

Physical Characterization and Material Properties of Epoxy Matrix Nanocomposites Containing Functionalized Single-Walled Carbon Nanotubes