Narrow Results

Nanodiamonds (NDs) have unique optical and mechanical characteristics, surface chemistry, extensive surface area and biocompatibility, and they are nontoxic, rendering them suitable for a diverse range of applications. Recently, NDs have received significant attention in nano-biomedical engineering. This review discusses the recent advancement of NDs’ biomedical engineering, historical background, basic introduction to nanoparticles and development. We summarize NDs’ synthesis technique, properties and applications. Two methodologies are used in ND synthesis: bottom-up and top-down. We cover synthesis methods, including detonation, ball milling, laser ablation, chemical vapor deposition (CVD) and high pressure and high temperature (HPHT); discuss the properties of NDs, such as fluorescence and biocompatibility. Due to these properties, NDs have potential applications in biomedical engineering, including bioimaging, biosensing, drug delivery, tissue engineering and protein mimics. Further, it provides an outlook for future progress, development and application of NDs in biological and biomedical areas.

Here we report a safer, easier, and quicker chemical route for synthesis of CdSe quantum dots (QDs), followed by their characterizations by UV/vis Spectroscopy (UV/vis), X-ray diffraction study (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and fluorescence (FL) spectroscopy. The average size of the quantum dots is 7.5 nm. Fluorescence study reveals that CdSe quantum dots emit green light when excited by optical source of wavelength of 550 nm or less.

Lanthanide-doped luminescent nanoscale materials have great potential applications in biological researches. Herein, we reported a novel and mild method for one-step synthesis of chitosan/NaGdF₄:Eu³⁺ nanocomposites. The luminescent Eu³⁺ ions and magnetic resonance imaging (MRI) contrast agent Gd³⁺ ions were incorporated to these biocompatible nanocomposites. The resultant nanocomposites exhibited strong fluorescence and attractive magnetic features. The nanocomposites also have pure hexagonal phase with uniform size of about 65 nm. FT-IR spectra revealed that these nanocomposites were successfully coated by hydrophilic chitosan, whose amine groups conferred the nanocomposites excellent dispensability in aqueous solution. Besides, the MTT assay and laser confocal microscopy images have confirmed the good biocompatibility of the nanocomposites. These results indicated that the as-prepared nanocomposites could be used as an excellent targeted imaging agent in biological fields.

Glutathione (GSH), the protective agent and reducing agent, has been widely used to prepare gold nanoclusters (GSH-Au NCs) with stable fluorescence properties and negative charge of the surface. Meanwhile, polyethyleneimine (PEI) was used as the modification agent to synthesize magnetic ferroferric oxide nanoparticles (Fe₃O₄) with fantastic dispersibility and positive charge of the surface. Based on the electrostatic adsorption force, magnetic nano-Fe₃O₄@GSH-Au NCs core–shell microspheres composed of magnetic Fe₃O₄ nanoparticles modified by PEI as the core and GSH-Au NCs as the shell were assembled. The prepared Fe₃O₄@GSH-Au NCs microspheres harbored a uniform size (88.6nm), high magnetization (29.2emu/g) and excellent fluorescence. Due to the coordination bond action between Au atom and sulfhydryl (–SH), amino (–NH₂), carboxyl (–COOH) in sweat, Fe₃O₄@GSH-Au NCs could combine with latent fingerprints. In addition, Fe₃O₄@GSH-Au NCs with good fluorescence and magnetism could detect fingerprints on various objects. Significantly, the powders were not easy to suspend in the air, which avoided the damage to the health of forensic experts and the fingerprints by only powder contacting. Above all, Fe₃O₄@GSH-Au NCs was successfully applied to the latent fingerprint visualization, which has great potential in forensic science.

In this work, water-soluble and blue-emitting carbon nanodots (CDs) were synthesized from apple peels for the first time via one-step hydrothermal method. The synthetic route is facile, green, economical and viable. The as-prepared CDs were characterized thoroughly by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman, Fourier transform infrared (FT-IR), X-ray photoelectron (XPS), fluorescence and UV–Vis absorption spectroscopy in terms of their morphology, surface functional groups and optical properties. The results show that these CDs possessed ultrasmall size, good dispersivity, and high tolerance to pH, ionic strength and continuous UV irradiation. Significantly, the CDs had fast and reversible response towards temperature, and the accurate linear relationship between fluorescence intensity and temperature was used to design a novel nanothermometer in a broad temperature range from 5 to 65${}^{\circ }$C facilely. In addition, the fluorescence intensity of CDs was observed to be quenched immediately by Cr(VI) ions based on the inner filter effect. A low-cost Cr(VI) ions sensor was proposed employing CDs as fluorescent probe, and it displayed a wide linear range from 0.5 to 200$\mu$M with a detection limit of 0.73$\mu$M. The practicability of the developed Cr(VI) sensor for real water sample assay was also validated with satisfactory recoveries.

Phenolic compounds, especially 4-nitrophenol (4-NP), and chromium (VI) are highly toxic environmental pollutants. Thus, it is significantly important to establish a rapid and sensitive sensor for 4-NP and Cr(VI) monitoring in environment. In this paper, a novel approach has been adopted where E. coli-derived CDs (CDs-WT) prepared by one step hydrothermal method previously and sensitized by ampicillin (turn-on) were used as fluorescence nanoprobe (CDs-WT-Amp) for 4-NP and Cr(VI) determination based on the inner filter effect quenching mechanism (turn-off). Then, the quenching fluorescence was reversed by addition of ampicillin (turn-on). The linear ranges of 4-NP and Cr(VI) detection were 0–50$\mu$M and 0–25$\mu$M, with the limits of detection 88.89nM and 64.75nM, respectively. The “turn-on-on-off-on” fluorescent nanosensor system was successfully used to determine Cr(VI) and 4-NP in water with satisfactory results. It shows that the “turn-on-off-on” nanoprobe has great promising potential for application to environmental pollutant detection.

Highly blue fluorescence carbon dots (CDs-MCM) were successfully prepared via a simple hydrothermal method with citric acid and ethylene diamine tetraacetic acid doped mesoporous silica MCM-41. The CDs-MCM exhibited uniform particle size and possessed good excitation-dependent characteristic. It showed highly selectivity and sensitivity in detection of Cr(VI), folic acid and good linear ranges of 0–37.5$\mu$M ($R^2=0.9903$) and 0–50$\mu$M ($R^2=0.9949$). The low detection limits were 79.31nM and 118.73nM for Cr(VI) and folic acid, respectively. It revealed that inner filter effect dominated in Cr(VI) quenching of the CDs-MCM fluorescent, while that of folic acid belonged to static quenching. The CDs-MCM were successfully used to detect the Cr(Vl) and folic acid in water and vegetable samples with satisfactory results. It provided new insight into environmental Cr(VI) and folic acid detection.

The “green synthesis” method is environmentally benign and cost-effective. This research study adopted an environmentally compatible method for creating Zinc oxide nanoparticles (ZnO NPs) using the capping element Solanum nigrum leaf extract. The X-ray diffraction, Fourier transforms infrared spectroscopy, energy dispersive X-ray analysis, UV-visible spectroscopy, fluorescence spectroscopy, field emission scanning electron microscopy, and antibacterial investigations were employed to evaluate the structural, spectroscopic, and antibacterial characterizations of the green synthesized ZnO NPs. It was shown that the generated ZnO NPs had a typical particle size of 27.75 nm and a wurtzite hexagonal form. FTIR spectroscopy has confirmed the presence of the functional groups in the generated sample. By using EDX analysis, the ZnO NPs’ fabrication and chemical composition have been determined. The surface texture and aggregation of nanostructure entities were examined using FESEM micrographs. Based on UV-Vis investigations, the bandgap of the ZnO NP was calculated to be 3.82 eV. The fluorescent spectra revealed a significant emission peak at 542 nm (green) for an excitation wavelength of 270 nm. The broad Stokes shift observed in fluorescent spectra is beneficial for practical purposes. The results of the antibacterial test shows that the as-synthesized ZnO NPs can be used in the healthcare and environmental sectors to prevent the growth of harmful bacteria.