A facile and novel synthetic method for the preparation of hydroxyl capped fluorescent carbon nanoparticles

What makes carbon nanoparticle a potent material for biological application?

Carbon materials are generally utilized in the form of carbon allotropes and their characteristics are exploited as such or for improving the thermal, electrical, optical, and mechanical properties of other biomaterials. This has now found a broader share in conventional biomaterial space with the generation of nanodiamond, carbon dot, carbon nanoparticles (CNPs), and so forth. With properties of better biocompatibility, intrinsic optical emission, aqueous suspendability, and easier surface conjugation possibilities made CNPs as one of the fore most choice for biological applications especially for use in intracellular spaces. There are various reports available presenting methods of preparing, characterizing, and using CNPs for various biological applications but a collection of information on what makes CNP a suitable biomaterial to achieve those biological activities is yet to be provided in a significant way. Herein, a series of correlations among synthesis, characterization, and mode of utilization of CNP have been incorporated along with the variations in its use as agent for sensing, imaging, and therapy of different diseases or conditions. It is ensembled that how simplified and optimized methods of synthesis is correlated with specific characteristics of CNPs which were found to be suitable in the specific biological applications. These comparisons and correlations among various CNPs, will surely provide a platform to generate new edition of this nanomaterial with improvised applications and newer methods of evaluating structural, physical, and functional properties. This may ensure the eventual use of CNPs for human being for specific need in near future. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Biosensing Diagnostic Tools > In Vitro Nanoparticle-Based Sensing Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Preparation of Zirconium Hydrogen Phosphate Coatings on Sandblasted/Acid-Etched Titanium for Enhancing Its Osteoinductivity and Friction/Corrosion Resistance

Background

Sandblasted/acid-etched titanium (SLA-Ti) implants are widely used for dental implant restoration in edentulous patients. However, the poor osteoinductivity and the large amount of Ti particles/ions released due to friction or corrosion will affect its long-term success rate.

Purpose

Various zirconium hydrogen phosphate (ZrP) coatings were prepared on SLA-Ti surface to enhance its friction/corrosion resistance and osteoinduction.

Methods

The mixture of ZrCl₄ and H₃PO₄ was first coated on SLA-Ti and then calcined at 450°C for 5 min to form ZrP coatings. In addition to a series of physiochemical characterization such as morphology, roughness, wettability, and chemical composition, their capability of anti-friction and anti-corrosion were further evaluated by friction-wear test and by potential scanning. The viability and osteogenic differentiation of MC3T3-E1 cells on different substrates were investigated via MTT, mineralization and PCR assays.

Results

The characterization results showed that there were no significant changes in the morphology, roughness and wettability of ZrP-modified samples (SLA-ZrP0.5 and SLA-ZrP0.7) compared with SLA group. The results of electrochemical corrosion displayed that both SLA-ZrP0.5 and SLA-ZrP0.7 (especially the latter) had better corrosion resistance than SLA in normal saline and serum-containing medium. SLA-ZrP0.7 also exhibited the best friction resistance and great potential to enhance the spreading, proliferation and osteogenic differentiation of MC3T3-E1 cells.

Conclusion

We determined that SLA-ZrP0.7 had excellent comprehensive properties including anti-corrosion, anti-friction and osteoinduction, which made it have a promising clinical application in dental implant restoration.

Advances and Challenges of Fluorescent Nanomaterials for Synthesis and Biomedical Applications

With the rapid development of nanotechnology, new types of fluorescent nanomaterials (FNMs) have been springing up in the past two decades. The nanometer scale endows FNMs with unique optical properties which play a critical role in their applications in bioimaging and fluorescence-dependent detections. However, since low selectivity as well as low photoluminescence efficiency of fluorescent nanomaterials hinders their applications in imaging and detection to some extent, scientists are still in search of synthesizing new FNMs with better properties. In this review, a variety of fluorescent nanoparticles are summarized including semiconductor quantum dots, carbon dots, carbon nanoparticles, carbon nanotubes, graphene-based nanomaterials, noble metal nanoparticles, silica nanoparticles, phosphors and organic frameworks. We highlight the recent advances of the latest developments in the synthesis of FNMs and their applications in the biomedical field in recent years. Furthermore, the main theories, methods, and limitations of the synthesis and applications of FNMs have been reviewed and discussed. In addition, challenges in synthesis and biomedical applications are systematically summarized as well. The future directions and perspectives of FNMs in clinical applications are also presented.

Simple in situ functionalization of carbon nanospheres

Functionalized carbon nanospheres have been synthesized in situ via a facile chemical vapor deposition strategy, fabricated by the pyrolysis of toluene/ethanol mixtures at different percentages (0, 1, 2, 3, 4, and 5 wt% of ethanol). The as-grown nanospheres have been characterized using transmission electron microscopy, scanning electron microscopy, Raman and Fourier transform infrared spectroscopy, x-ray diffraction, nitrogen adsorption, zeta potential measurements and x-ray photoelectron spectroscopy. Results indicate that the incorporation of ethanol in the precursor solution reflected in the presence of oxygen and hydrogen functional groups, the highest functionalized nanospheres without compromising the morphology of the sample were yielded at 3 wt% concentration. These in situ added functional groups rendered the carbon nanostructures enhancedly dispersible and stable in water, avoiding post-synthesis and harsh chemicals processing; envisaging thus applications of the nanospheres in the biomedical field where hydrophilicity of the nanomaterials is mandatory.

Water-Dispersible Candle Soot-Derived Carbon Nano-Onion Clusters for Imaging-Guided Photothermal Cancer Therapy

Herein, water-dispersible carbon nano-onion clusters (CNOCs) with an average hydrodynamic size of ≈90 nm are prepared by simply sonicating candle soot in a mixture of oxidizing acid. The obtained CNOCs have high photothermal conversion efficiency (57.5%), excellent aqueous dispersibility (stable in water for more than a year without precipitation), and benign biocompatibility. After polyethylenimine (PEI) and poly(ethylene glycol) (PEG) modification, the resultant CNOCs-PEI-PEG have a high photothermal conversion efficiency (56.5%), and can realize after-wash photothermal cancer cell ablation due to their ultrahigh cellular uptake (21.3 pg/cell), which is highly beneficial for the selective ablation of cancer cells via light-triggered intracellular heat generation. More interestingly, the cellular uptake of CNOCs-PEI-PEG is so high that the internalized nanoagents can be directly observed under a microscope without fluorescent labeling. Besides, in vivo experiments reveal that CNOCs-PEI-PEG can be used for photothermal/photoacoustic dual-modal imaging-guided photothermal therapy after intravenous administration. Furthermore, CNOCs-PEI-PEG can be efficiently cleared from the mouse body within a week, ensuring their excellent long-term biosafety. To the best of the authors' knowledge, the first example of using candle soot as raw material to prepare water-dispersible onion-like carbon nanomaterials for cancer theranostics is represented herein.

TiO2 Nanowires from Wet-Corrosion Synthesis for Peptide Sequencing Using Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

In this work, TiO₂ nanowires synthesized from a wet-corrosion process were presented for peptide sequencing by photocatalytic reaction with UV radiation. For the photocatalytic decomposition of peptides, the peptide sample was dropped on a target plate containing synthesized TiO₂ nanowire zones and UV-irradiated. Subsequently, the target plate was analyzed by laser desorption/ionization time-of-flight (LDI-TOF) mass spectrometry using the synthesized TiO₂ nanowires as a solid matrix. The feasibility of peptide sequencing based on the photocatalytic reaction with the synthesized TiO₂ nanowires was demonstrated using six types of peptides GHP9 (G₁-H-P-Q-G₂-K₁-K₂-K₃-K₄, 1006.59 Da), BPA-1(K₁-S₁-L-E-N-S₂-Y-G₁-G₂-G₃-K₂-K₃-K₄, 1394.74 Da), PreS1(F₁-G-A-N₁-S-N₂-N₃-P₁-D₁-W-D₂-F₂-N₄-P₂-N₅, 1707.68 Da), HPQ peptide-1 (G-Y-H-P-Q-R-K, 884.45 Da), HPQ peptide-2 (K-R-H-P-Q-Y-G, 884.45 Da), and HPQ peptide-3 (R-Y-H-P-Q-G-K, 884.45 Da). The identification of three different peptides with the same molecular weight was also demonstrated by using the synthesized TiO₂ nanowires for their photocatalytic decomposition as well as for LDI-TOF mass spectrometry as a solid-matrix.

Fabrication of Water Jet Resistant and Thermally Stable Superhydrophobic Surfaces by Spray Coating of Candle Soot Dispersion

A facile synthesis method for highly stable carbon nanoparticle (CNP) dispersion in acetone by incomplete combustion of paraffin candle flame is presented. The synthesized CNP dispersion is the mixture of graphitic and amorphous carbon nanoparticles of the size range of 20-50 nm and manifested the mesoporosity with an average pore size of 7 nm and a BET surface area of 366 m²g^-1. As an application of this material, the carbon nanoparticle dispersion was spray coated (spray-based coating) on a glass surface to fabricate superhydrophobic (water contact angle > 150° and sliding angle < 10 °) surfaces. The spray coated surfaces were found to exhibit much improved water jet resistance and thermal stability up to 400 °C compared to the surfaces fabricated from direct candle flame soot deposition (candle-based coating). This study proved that water jet resistant and thermally stable superhydrophobic surfaces can be easily fabricated by simple spray coating of CNP dispersion gathered from incomplete combustion of paraffin candle flame and this technique can be used for different applications with the potential for the large scale fabrication.

Resistance in bacteria and indirect beta-lactamase detection in E. coli isolated from Culex pipiens detected by matrix-assisted laser desorption ionization time of flight mass spectrometry

The aim of this study was detections of antibiotic resistance and resistance mechanism in bacteria isolated from mosquitos (Culex pipiens) living near humans. Therefore, antibiotic resistance in bacteria isolated from Culex pipiens was investigated by disk diffusion test and MIC E-test in this study. MALDI-TOF mass spectrometry was used for detection of resistant mechanism. In this study, hydrolytic breakdown products after a few hours of incubation of the bacteria isolated from Culex pipiens were detected. Results show that enzymatic destruction of ampicillin by beta-lactamases is able to be detected by MALDI-TOF mass spectrometry from wild strains of potential pathogens. The MALDI-TOF mass spectrometry is useful method for routine detection of beta-lactamases resistant mechanism, but overnight incubation of pure culture is necessary. The results are important for proper and fast intervention to limit the spread of beta-lactamase-producing wild bacteria and provide information for appropriate initial therapy of the infections caused by these microbes.

One-step microwave synthesis of N-doped hydroxyl-functionalized carbon dots with ultra-high fluorescence quantum yields

A one-step microwave synthesis of N-doped hydroxyl-functionalized carbon dots (CDs) with ultra-high fluorescence quantum yields (QYs) of 99% is reported. These ultra-high QY CDs were synthesized using citric acid and amino compound-containing hydroxyls like ethanolamine and tris(hydroxylmethyl)aminomethane. Amino and carboxyl moieties can form amides through dehydration condensation reactions, and these amides act as bridges between carboxyl and hydroxyl groups, and modify hydroxyl groups on the surface of the CDs. The entire reaction can be carried out within 5 min. When the molar ratio of reactants is 1 : 1, the hydroxyl and graphitic nitrogen content is the highest, and the synergy leads to a high ratio between the radiative transition rate and nonradiative transition rate as well as a high QY. The developed pathway to N-doped hydroxyl-functionalized CDs can provide unambiguous and remarkable insights into the design of highly luminescent functionalized carbon dots, and expedite the applications of CDs.

Elucidating the structure of carbon nanoparticles by ultra-performance liquid chromatography coupled with electrospray ionisation quadrupole time-of-flight tandem mass spectrometry

A fast and accurate ultra-performance liquid chromatography coupled with electrospray ionisation quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) method was developed for the separation and structural elucidation of fluorescent carbon nanoparticles (CNP). The CNP was synthesised from microwave-assisted pyrolysis of citric acid (CA) and 1,2-ethylenediamine (EDA). By using UPLC separation, the CNP product was well separated into ten fractions within 4.0 min. Based on high-accuracy MS and MS/MS analyses, the CNP species were revealed to display six kinds of chemical formulas, including (C10H20N4O5)n, (C8H12N2O5)n, (C16H22N4O9)n, (C6H8O7)n, (C14H18N2O11)n, and (C14H16N2O10)n. In particular, our study revealed for the first time that the CNP species exist as supramolecular clusters with their individual monomers units linked together through non-covalent bonding forces. These findings clearly indicated the usefulness of UPLC-ESI-Q-TOF-MS/MS in identifying the chemical composition of CNP product. It is anticipated that our proposed methodology can be applied to study the structure-property relationships of CNP, facilitating in the production of CNP with desirable spectral features.

Analysis of benzylpenicillin in milk using MALDI-TOF mass spectrometry with top-down synthesized TiO2 nanowires as the solid matrix

In this work, the wet-corrosion process for the synthesis of titanium oxide (TiO2) nanowires in the anatase phase was optimized as the solid matrix in MALDI-TOF mass spectrometry, and the solid matrix of the TiO2 nanowires was applied to the detection of antibiotics in a daily milk sample. The influence of the alkali concentration and the heat treatment temperature on the crystal structure of the TiO2 nanowires was investigated. The ionization activity of the TiO2 nanowires was estimated for each synthetic condition using amino acids as model analytes with low molecular weights. For the detection of antibiotics in milk, benzylpenicillin was spiked in daily milk samples, and MALDI-TOF mass spectrometry with the TiO2 nanowires was demonstrated to detect the benzylpenicillin at the cut-off concentration of the EU directive.

Nylon nanoweb with TiO2 nanoparticles as a solid matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

RATIONALE

The solid matrices used for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) enable the analysis of small molecules by preventing fragmentations of organic matrix molecules in the low mass-to-charge ratio (m/z) range. In this work, a nylon nanoweb with TiO(2) particles was developed as a solid matrix for MALDI-TOFMS to improve the low intensities of mass peaks, narrow detection ranges and low signal-to-noise levels.

METHODS

The nylon nanoweb with TiO(2) particles was prepared by simultaneously electrospinning a nylon nanoweb and electrospraying TiO(2) nanoparticles measuring 25 nm in diameter to form TiO(2) spheres 300 nm in diameter.

RESULTS

MS of multiple analytes was demonstrated in the low molecular weight range using eight amino acids. Additionally, leucine-enkephalin (555.6 g/mol) and cyclic citrullinated peptide (1668 g/mol) were used as model analytes to test the feasibility of a nylon nanoweb containing TiO(2) particles as a solid matrix for MALDI-TOFMS.

CONCLUSIONS

The nylon nanoweb with TiO(2) particles can be applied for the detection of volatile small molecule analytes in the m/z ratio range of small molecules.