Narrow Results

A novel core–shell hybrid nanostructure was constructed by employing gold nanorod (AuNR) combined with rhodamine B (RB) as a core and silica as a shell. The poly(sodium 4-styrenesulfonate) (PSS), a negatively charged polyelectrolyte, played the role of linker to electrostatically trap RB on AuNRs. Due to the fluorescence spectral overlap between RB and AuNRs at 560 nm, the red fluorescence and enhanced green fluorescence of the hybrid nanostructures were observed obviously, which is capable for dual-color labeling. To reduce toxic side effects of AuNRs, silica was coated on AuNRs as a shell to fabricate the novel core–shell hybrid nanostructure function as a dual-color labeling for cancer-cell imaging. The fabricated composite structures were characterized by transmission electron microscopy (TEM), absorption spectrum, fluorescence spectrum, zeta potential measurements and laser scanning confocal microscope (LSCM). The experiment results confirmed that the obtained hybrid nanostructures provided excellent photostability, biocompatibility and active surface for further biological functionalization. The novel composite structures may have great potential application in cell multicolor labeling and imaging instead of traditional fluorescent dyes.

Multifunctional photoluminescent (PL) nanomaterials have attracted considerable interest in terms of their potential applications in the field of clinical medicine. Carbon dots (CDs), as emerging optical nanomaterials, are promising in various fields including biological imaging, drug transport and nerve tracing. However, little research has investigated on bone tissue engineering as of now. In this study, a new kind of bifunctional Zn${}^{2+}$-doped carbon dots (Zn-CDs) has been synthesized by a one-step hydrothermal method, Zn-CDs show effective fluorescent imaging and induce osteoblastic differentiation abilities in vitro. Moreover, compared with the raw material, Zn-CDs exhibited more effective osteoblastic differentiation promoting capability. Overall, the biocompatible nanomaterial Zn-CDs show potential to be used as a promising novel nanodrug for bone loss therapy and also a monitor of cell variation by fluorescence imaging.

A fluorescence probe has been synthesized for the detection of osthole using the nitrogen-doped carbon dots (NCDs) as shown in Fig. 1. The NCDs were fully characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR). Under the optimal experimental conditions, the NCDs fluorescence probe was highly selective and sensitive to osthole. The linear response range for osthole was 5.0–75$\mu$M with a detection limit of 38nM. The mechanism of the interaction of osthole and NCDs was discussed. The fluorescence probe has been applied to the analysis of biological samples. The as-synthesized NCDs with high fluorescence intensity, low toxicity and good biocompatibility were applied to cell imaging.

Graphene quantum dots (GQDs) have been extensively used in biosensors and bioimaging. Heteroatom-doped GQDs can regulate material properties and endow them to improve structural and physicochemical properties. In this work, N,S-GQDs were prepared through a high-temperature pyrolysis method using L-cysteine and citric acid as the precursors. The morphology and structure of nanocomposites were identified by TEM, X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), and FTIR. The as-prepared N,S-GQDs show bright blue fluorescence with satisfactory fluorescence quantum yield. N,S-GQDs display significant response to riboflavin, achieving a low detection limit of 27nM. The reaction of N,S-GQDs to riboflavin is mainly governed by static quenching. The detection of riboflavin in real samples has been performed to demonstrate its practical application. The obtained N,S-GQDs have low cytotoxicity and have been applied successfully in cell imaging.

There is an increasing interest in the use of silica nanoparticles (NPs) for bioapplications. Highly mesoporous fluorescein dye-doped silica NPs that can carry a drug payload have been successfully synthesized through a facile microemulsion process. The morphology of the as-prepared silica NPs were characterized by scanning electron microscope and transmission electron microscope, whereas their optical properties were studied by photoluminescence spectroscopy. The results revealed that these silica NPs exhibit excellent properties, including large pore volume, a narrow size distribution and strong fluorescent properties. The synthesized silica NPs showed a good biocompatibility and a low cytotoxicity when incubated in a murine fibroblast L-929 cell line. The obtained silica NPs were further used as drug delivery carriers to investigate the in vitro drug release properties using doxorubicin (DOX) as a representative drug model. It was shown that synthesized silica NPs well sustained drug release properties, suggesting their potential applications for drug delivery.

A series of nanoscale-level metal complexes with bidentate (N₂MCl${}_2)$ and tetradentate (MN) chromophores have been employed as efficient cisplatin analogues and intercalating agents towards DNA and studied their anticancer activities against A549 cancer cells. Among them, complexes 1–6 exist with two labile chlorides similar to the chemotherapeutic inorganic drug cisplatin, which have been found to bind covalently with herring sperm DNA. Complexes 7–12 may undergo an intercalative mode of binding due to their structural differences relative to 1–6. The intrinsic binding constants obtained for complexes 7–12 were also significantly varied due to their structure and binding mode ($0.95-1.6\times 10^5$ and $1.5-2.4\times 10^4$ M${}^{-1}$ for complexes, 1–3 and 4–6, respectively). However, complexes 7–9 have shown much stronger binding constants ($0.98-1.64\times 10^6$ M${}^{-1}$) due to their existing planarity which leads them to strong intercalation than their counterparts, 10–12 ($3.19-4.14\times 10^4$ M${}^{-1}$). The significantly higher binding constant values for complexes 1–3 may due to their planar structure and also may possibly lead to intercalation. Though all these complexes (1–12) have shown almost similar binding constants (1.26–2.0) in the electrochemical analysis, it implies that these complexes interact towards DNA with equal strength at their reduced oxidation (M${}^{+I}$) states. The obtained results in various spectral, electrochemical, relative viscosity changes, DNA cleavage studies revealed that these complexes 1–6 mimic the functional properties of cisplatin. Therefore, these nanostructured complexes could be substituted for cisplatin as a new family of non-platinum-based anticancer drugs in the future, after a sequence of in-vivo investigation. Their potential activity against A549 cancer cells has also been recorded using Hoechst staining and Propidium iodide images.

In this paper, we report a one-step tumor cell detection approach based on the dynamic morphological behavior tracking of cancer cells on a ligand modified surface. Every cell on the surface was tracked in real time for several minutes immediately after seeding until these were finally attached. Cancer cells were found to be very active in the aptamer microenvironment, changing their shapes rapidly from spherical to semi-elliptical, with much flatter spread and extending pseudopods at regular intervals. When incubated on a functionalized surface, the balancing forces between cell surface molecules and the surface-bound aptamers, together with the flexibility of the membranes, caused cells to show these distinct dynamic activities and variations in their morphologies. On the other hand, healthy cells remained distinguishingly inactive on the surface over the same period. The quantitative image analysis of cell morphologies provided feature vectors that were statistically distinct between normal and cancer cells.