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Au@palladium oxide nano-sunflowers are fabricated for ultrasensitive surface-enhanced Raman scattering analysis.

The flexible surface-enhanced Raman scattering (SERS) platform has ceaselessly propelled the development of point-of-care testing (POCT) in diverse fields. Herein, we report a facile strategy for the SERS-chemometric analysis of four β-blockers (bisoprolol, metoprolol, acebutolol and esmolol) based on a super-sticky mussel-inspired hydrogel SERS tape. The surface morphology and mechanical properties of the hydrogel tape can be easily controlled by adjusting the compositional ratio. The optimized tape with excellent toughness and adhesiveness allows efficient collection of analytes through a simple "paste and peel off" approach, further by spraying with silver nanoparticles using a household sprayer to instantly assemble a flexible SERS substrate, the analytes can then detected by a portable Raman spectrometer. This POCT strategy enables the identification and discrimination of four similar β-blockers with high sensitivity and accuracy in combination with the statistical algorithms. The developed SERS tape is finally utilized for the recognition of β-blockers in simulated urine solution, which realizes a limit of detection of 1.0 ng mL

A versatile strategy for smart fluorescent materials is lacking due to their diverse responding mechanisms and incompatibility of responsive behaviors. Herein an adaptable strategy is presented toward a multi-stimuli-responsive fluorescent material with stage-by-stage responsive behavior by blending linear polymers modified with different stimulus-responsive moieties and AIE cross-linker. Under stimuli, the linear polymer can cross-link with the cross-linker to form networks, which intrinsically restrict the intramolecular rotation of the AIE molecule to induce strong emission. A unified stimuli-responsive mechanism is involved in that various stimuli are transferred through the organized "stimulus-crosslink-emission" process. This strategy ensures the compatibility of different stimuli-responses and the adjustability of stimulus-response behavioral logic. These multi-stimuli-responsive fluorescent materials exhibited strong accessibility and adaptability for information encryption.

Surface-enhanced Raman scattering (SERS) spectroscopy has attracted tremendous interest as a highly sensitive label-free tool to detect pollutants in aqueous environments. However, the high cost and poor reusability of conventional SERS substrates restrict their further applications in rapid and reproducible pollutant detection. Here, we report a reliable optical manipulation method to achieve rapid photothermal self-assembly of Au nanoparticles (AuNPs) in water within 30 s by a tapered optical fiber, which is utilized for highly sensitive SERS substrate preparation. The results show that the SERS substrate achieves low detection limits of 10−9 mol/L with an enhancement factor (EF) of 106 for chemical pollutants solutions, including thiram, pyrene, and rhodamine 6G. The SERS enhancement effect based on assembled AuNPs was more than 20 times that based on a gold colloid solution. As a result, the smart reversible assembly of AuNPs exhibits switchable plasmonic coupling for tuning SERS activity, which is promising for the application of SERS-based sensors and environmental pollutant detection.

Water-in-oil droplet generation for object encapsulation is of increasing importance in biochemical reaction, drug diagnostics, and environmental science. Optofluidic technique is a powerful tool for manipulating mesoscopic particles and droplets within a continuous liquid phase. Here, we report a flexible and miniaturized droplet generator based on a microvortex chip by light-heat energy conversion to fuse, trap, and release picoliter aqueous droplets in the immiscible carrier oil. The droplet sizes in the generators can be tuned by the flow rate of the vortices. Further, it is demonstrated that the generated droplet can realize size-selective encapsulation of micro-matters with tunable rotating trajectories. The results showed that the microvortex-based droplet generator propose a method for the stable fusion and encapsulation of droplet with controllable positions and volumes. This system will provide a controllable microfluidic environment for droplet tweezers, micro-reactors, micro-mixers, and object encapsulation in practical applications.

By means of a simple and photo-induced method, four colors of molybdenum oxide quantum dots (MoOx QDs) have been synthesized, using Mo(CO)6 as the structural guiding agent and molybdenum source. The as-prepared MoOx QDs display diverse optical properties due to the different configurations of oxygen vacancies in various nanostructures. Among them, crystalline molybdenum dioxide (MoO2) with a deep blue color shows the most intense localized surface plasmon resonance effect in the near-infrared (NIR) region. The strong NIR absorption endows MoO2 QDs with a high photothermal conversion efficiency of 66.3%, enabling broad prospects as a photo-responsive nanoagent for photothermal therapy of cancer. Moreover, MoO2 QDs can also serve as a novel semiconductor substrate for ultrasensitive surface-enhanced Raman scattering (SERS) analysis of aromatic molecules, amino acids and antibiotics, with SERS performance comparable to that of noble metal-based substrates. The therapeutic applications of MoO2 QDs open up a new avenue for tumor nanomedicine.

Herein, a facile and green one-pot route was firstly developed for in situ grown Au nanoparticles on oxygen deficient molybdenum oxide nanosheets (MoOx-AuNSs) without extrinsic reductant. The change of molybdenum‑oxygen bonds and transformation of valence state of Mo element from Mo4+ and Mo5+ to Mo6+ species in MoOx after the redox reaction were observed. The nanocomposites exhibited tunable surface-enhanced Raman scattering (SERS) activity by adjusting the synthesis condition to assemble optimal hot spots. Utilization of MoOx-AuNSs as novel SERS substrate, ultrasensitive SERS detection of IR-780 iodine, a molecular probe used in biomedicine, was then achieved under different environments. Finally, the molecular fingerprint analysis of cancer cells based on MoOx-AuNSs was also completed, indicating the promising potential of MoOx-based SERS probe for bio-applications.

In order to realize the accurate and early diagnosis of liver fibrosis, a long slow pathological process which may lead to cirrhosis or even liver cancer, liver targeting tags made up of gold nanostars and glycyrrhetinic acid are reported in this paper. Gold nanostars (GNSs) and GNS liver targeting tags (GLTTs) were injected into model mice with stage S1 liver fibrosis and normal mice via the tail vein respectively, then the SERS spectra were collected. GLTTs had a better detection effect on liver tissue than unmodified GNSs (12.85 times), and better detection reproducibility as well. Moreover, according to the MTT and survival analysis experiments, GLTTs also had better biocompatibility. Hence, the changes of 10 SERS signals and other substances in the early stage of liver fibrosis were analyzed at the molecular level, and the SERS characteristic peaks that could be used for the diagnosis of early liver fibrosis were screened out. Revealed by the experimental results, the GLTTs designed and prepared were applicable to the efficient SERS detection of early liver fibrosis in mice, and the strategy we have proposed might be a potential approach for the early diagnosis of this disease in clinics.

MoO3−x nanoparticles are a series of rising optothermal materials due to their surface plasmonic absorption features. However, their poor stability limits their further applications. Herein, a facile, one-step hydrothermal method was conducted to synthesize MoO3−x nano-dots coated with polyvinyl pyrrolidone. The wrapped polymer chains give MoO3−x good hydrophilicity and excellent stability. The constitutional formula for MoO3−x was calculated to be MoO2.63, as determined by X-ray photoelectron spectroscopy. The as-synthesized MoO2.63 nano-dumplings could be easily monodispersed in water or PBS solution and showed high tolerance against aging, heat, laser exposure and chemical etching. The superior absorption of the MoO2.63 nano-dumplings in the near-infrared (NIR) region also endows them with promising potential for remote control microvalve application and photothermal cancer therapy effect.

The favorable biocompatibility, biodegradability and broadband absorption in the ultraviolet to near-infrared (NIR) region have made black phosphorus (BP) a new generation two-dimensional nanomaterial with great potential for photothermal therapy (PTT). However, an appropriate but not low dosage of nanoagent is required to achieve the satisfactory therapeutic effect in BP-based NIR PTT, due to the decreasing light absorption of BP in the NIR region. In this work, nanohybrids composed of BP nanosheets and several polypyrrole (PPy) nanoparticles attached to them (BP/PPy NSs) are fabricated for high-performance NIR PTT, benefiting from the superimposed NIR absorption characteristics of the two components. The nanocomposites exhibit irregular, speckled and flake-like morphologies with good biocompatibility and superior NIR photothermal transduction efficiency compared with that of the bare nanosheets. The utilization of BP/PPy NSs as novel nanotherapeutic agent for enhanced NIR photothermal cancer therapy is accomplished in vitro and in vivo.

As one of the prospective two-dimensional nanomaterials, black phosphorus (BP), which has excellent physical and chemical properties, has witnessed quick development in theranostic applications. The more recent advances in combining BP nanosheet (NS) with nanoparticles exhibit new opportunities to develop multifunctional nanocomposites. However, more effort should be devoted to elucidate the nanomaterial-cell interaction mechanism before the bio-applications of BP-nanoparticle hybrids. Herein, the intracellular behaviors of BP-gold nanoparticles (BP-Au NSs) are first investigated using the surface-enhanced Raman scattering (SERS) technique. The presence of Au nanoparticles on the surface of a BP sheet allows nanohybrids with excellent SERS activity to enhance the intrinsic Raman signals of cellular components located around the NSs. Data from an endocytosis inhibitor blocking assay reveal that the nanohybrids are mainly taken up by macropinocytosis and caveolae-dependent endocytosis, which are energy-dependent processes. Associated with colocalization experiments, nanohybrids are found to internalize into lysosomes and the endoplasmic reticulum. Moreover, the SERS difference spectrum is extracted after Raman-fluorescence colocalization statistical analysis to distinguish the molecular structural differences in the biochemical components of the two organelles. These findings supply a definite cellular mechanistic understanding of the nano-biointeractions of nanocomposites in cancer cells, which may be of great importance to the biomedical applications of nanotechnology in the future.

Flake-shaped nanohybrids based on black phosphorus (BP) have been developed as multifunctional theranostic nanoplatforms for drug delivery, phototherapy and bioimaging. In this work, we report a facile strategy for fabrication of black phosphorus-Au nanoparticle hybrids (BP-AuNPs), which reveal an extraordinary near-infrared (NIR) photothermal transduction efficiency and drug delivery capacity. The applications of the nanocomposites as therapeutic agents for high-performance chemo-photothermal tumor therapy are accomplished in vitro and in vivo. BP-AuNPs also exhibit wonderful surface-enhanced Raman scattering (SERS) activity under NIR laser excitation with a low Raman background, allowing BP-AuNPs to be used as a promising two-dimensional (2D) fingerprint nanoprobe for bio-SERS analysis. The cellular component identification and label-free live-cell bioimaging based on this type of 2D SERS substrate are generally investigated, which open up promising new perspectives in nanomedicine, including diagnosis, imaging and therapy.

The Au nanoparticles (Au NPs) with bumpy shapes take the advantages of the stronger localized surface plasmon resonance (LSPR) and more hot spots, which cause them to be the talented surface-enhanced Raman scattering (SERS) substrate. In this work, we reported a one-pot, rapid and green method to fabricate mutli-branched Au nanoparticle@graphene quantum dots (Au NP@GQDs) core-shell nanocomposites via using GQDs as the reducer without adding any other reagents for the first time. The hybrids with a mean diameter of ca. 47 nm have ultrathin 1-nm-thick GQDs shells which coat the flower-liked Au cores. The core-shell structure could provide a win-win pattern to substantially enhance the SERS signals of the dye molecules owing to the GQD coating for its high affinity to absorb the analytes and the bumpy Au NP-core for strong improvement of the LSPR. The Au NP@GQDs exhibited remarkably high SERS activity on different charged dyes, which revealed its universality on SERS detection. Further application of the nanocomposites for simple, sensitive and lable-free SERS detection of malachite green (MG), one of the illegal additives in aquaculture, was conducted, which revealed a superior SERS signals with the enhancement factor of 1.4 × 104 and the minimum detected concentration was as low as 0.5 nM. Moreover, the fantastic SERS repeatability and good structural stability also demonstrated the potential for SERS application. These properties make the flower-liked Au NP@GQDs a promising SERS substrate to detect the banned dye pollutants in the aquaculture and additive colorants in food industry.

Carcinoma-associated fibroblasts (CAFs), one of the most important components of a tumor microenvironment (TME), play a significant role in the complex tumorigenesis process. Herein, the evolution of CAFs in TME is elaborately investigated by surface-enhanced Raman spectroscopy (SERS), a molecular fingerprint technique. Two-dimensional (2D) nanocomposites consisting of gold nanoparticles and a supramolecular "PCsheet" self-assembled between 2D nanosheets and oxidized phosphatidylcholine (PC) are fabricated as SERS-active probes to specifically recognize the CD36 receptor on the cytomembrane of the fibroblasts, a reliable landmark of CAF development. The 2D SERS substrates can also illuminate the fingerprint information around the CD36 protein with high detection sensitivity, which helps elucidate the biochemical component transition in the protein mini-domain during carcinoma progression. Visualized data are then supplied by label-free SERS imaging to exploit the distribution of biomolecules on the plasma membrane. In addition, the repressed expression of CD36 in TME is detected in lung metastasis tumor-bearing mice. This study based on the 2D SERS technique opens up an alternative avenue for unveiling carcinoma-associated molecular events.

The synergistic integration of optofluidic and surface enhanced Raman scattering (SERS) sensing is a new analytical technique that provides a number of unique characteristics for enhancing the sensing performance and simplifying the design of microsystems. Here, we propose a reusable optofluidic SERS sensor by integrating Au nanoisland substrate (AuNIS)-coated fiber into a microfluidic chip. Through both systematic experimental and theoretical analysis, the sensor enables efficient self-cleaning based on its optical-to-heat-hydrodynamic energy conversion property. Besides, the sensor exhibits the instrument detection limit down to 10 − 13 m o l / L and enhancement factor of 10 6 for Rhodamine 6G. Our optofluidic SERS sensor with such a photothermal microfluidic-assisted self-cleaning method has the advantages of portability, simple operation, and high cleaning efficiency, which will provide a new, to the best of our knowledge, concept and approach for cost-effective and reusable sensors.

Microfluidic techniques have emerged as promising strategies for a wide variety of synthetic or biological sorting. Unfortunately, there is still a lack of sorting with automatic and handy operation. In contrast to passively generated vortices, the thermocapillary vortices produced by temperature gradient have the advantages of flexible manipulation, stable strength, and simple integration. In this Letter, we present a device used for the pump-free separation of particles through vortices interaction without external fluidic control systems required for the majority of existing devices. Specifically, the device induces a different flow type upon the actuation of optical power, and the flow functions, such as simultaneous pumping and sorting, agree with stimulation results very well. More importantly, our developed sorting device can achieve separations by means of tunable cutoff diameter size. Therefore, this versatile device can be utilized to sort complex samples with the advantages of portability, user-friendly control, and automation.

The development of two-dimensional (2D) transition metal dichalcogenides has been in a rapid growth phase for the utilization in surface-enhanced Raman scattering (SERS) analysis. Here, we report a promising 2D transition metal tellurides (TMTs) material, hafnium ditelluride ( HfTe 2 ), as an ultrasensitive platform for Raman identification of trace molecules, which demonstrates extraordinary SERS activity in sensitivity, uniformity, and reproducibility. The highest Raman enhancement factor of 2.32 × 10 6 is attained for a rhodamine 6G molecule through the highly efficient charge transfer process at the interface between the HfTe 2 layered structure and the adsorbed molecules. At the same time, we provide an effective route for large-scale preparation of SERS substrates in practical applications via a facile stripping strategy. Further application of the nanosheets for reliable, rapid, and label-free SERS fingerprint analysis of uric acid molecules, one of the biomarkers associated with gout disease, is performed, which indicates arresting SERS signals with the limits of detection as low as 0.1 mmol/L. The study based on this type of 2D SERS substrate not only reveals the feasibility of applying TMTs to SERS analysis, but also paves the way for nanodiagnostics, especially early marker detection.

Photothermal antibacterial methods are urgently needed in the treatment of bacterial infectious diseases and drug-resistant bacteria, which is due to the abuse of antibiotics leading to the production of drug-resistant bacteria, resulting in poor treatment of diseases. However, it is very challenging to improve the yield of nanomaterial preparation and surface modification, while also ensuring the enhancement of antibacterial properties. Herein, we report a tannic acid-assisted peeling method to prepare a single-layer tannic acid (TA) modified NbTe2 nanosheets (NbTe2/TA) with high production yield (≈ 52 ± 10%) and multiple antibacterial properties. NbTe2/TA nanosheets show uniform particle size and ultra-thin thickness. In near-infrared light, NbTe2/TA demonstrates excellent photothermal conversion performance and photothermal stability, further demonstrating the potential of NbTe2/TA for photothermal antibacterial applications. It is worth noting that TA has excellent antibacterial properties, which can further enhance the photothermal antibacterial properties of NbTe2/TA. Moreover, NbTe2/TA has been shown to have good biosecurity which does not damage epithelium and fibroblasts. To the best of our knowledge, the above NbTe2 stripping method is superior to the previously reported NbTe2 peeling method and is the first time applied to the study of photothermal antibacterial.

Photo-immunotherapy taking advantages of the immunogenic cell death (ICD) induced by photothermal therapy (PTT) to facilitate the systemic anti-tumor immunity has been exploited as a promising therapeutic approach for cancer. However, this kind of in situ tumor vaccine is of less efficacy due to the anisotropic immunogenicity profiles of dying cells after PTT. Herein, a facile strategy is proposed to activate the necroptosis, a programmed cell death with intense immunogenicity, in photothermal ablated cells by easily modulating the PTT parameters, which enables the optimal ICD for anti-tumor immunity. As an emerging 2D nanomaterial, black phosphorus (BP) serves as the near-infrared (NIR)-responsive nanoagent to trigger PTT. Necroptosis in ablated tumor cells is confirmed by the high expression of key proteins in necroptotic pathway. The necroptotic cells also exhibit considerable immunogenicity by the release of damage-associated molecular patterns to potentiate the immune responses. Further an immunologic adjuvant is grafted onto the BP nanosheets and the high-performance cancer photo-immunotherapy is achieved. This easy-to-access photo-immunotherapeutic strategy by in situ photothermal activation of necroptosis supplies new insights in the treatment of cancer.

Photo-immunotherapy taking advantages of the immunogenic cell death (ICD) induced by photothermal therapy (PTT) to facilitate the systemic anti-tumor immunity has been exploited as a promising therapeutic approach for cancer. However, this kind of in situ tumor vaccine is of less efficacy due to the anisotropic immunogenicity profiles of dying cells after PTT. Herein, a facile strategy is proposed to activate the necroptosis, a programmed cell death with intense immunogenicity, in photothermal ablated cells by easily modulating the PTT parameters, which enables the optimal ICD for anti-tumor immunity. As an emerging 2D nanomaterial, black phosphorus (BP) serves as the near-infrared (NIR)-responsive nanoagent to trigger PTT. Necroptosis in ablated tumor cells is confirmed by the high expression of key proteins in necroptotic pathway. The necroptotic cells also exhibit considerable immunogenicity by the release of damage-associated molecular patterns to potentiate the immune responses. Further an immunologic adjuvant is grafted onto the BP nanosheets and the high-performance cancer photo-immunotherapy is achieved. This easy-to-access photo-immunotherapeutic strategy by in situ photothermal activation of necroptosis supplies new insights in the treatment of cancer.

Previous studies have shown that nanoparticles can induce autophagy, and the main approach for investigating autophagy induced by nanoparticles is via traditional methods such as TEM and biochemical assay. These methods measurements suffer from the disadvantages of complicated experimental processes, cell destruction, as well as lack of characterization of individual stages of the autophagy pathway. Surface-enhanced Raman scattering (SERS) has been extensively used in biological applications. With the combination of SERS and chemometric methods, such as principal component analysis-linear discriminant analysis (PCA-LDA), identification and distribution mapping of endosomes and lysosomes in the endocytosis of Au nanoparticles has been achieved by segregating the spectra from complex SERS data sets in the previous study. In this study, silver@gold core–shell nanoparticles (Ag@Au NPs) were synthesized by reduction of gold ions on the surface of the silver nanoparticles, and the autophagy induced by Ag@Au NPs was studied with Ag@Au NPs serving both as an autophagy inducer and as a high-performance SERS substrate. Pro-survival autophagy induced by Ag@Au NPs was proved by the western blot assay, flow cytometry and fluorescent staining. Furthermore, the autophagy pathway in Ag@Au NPs-treated cells was first elucidated by SERS combined with a modified reference-based PCA-LDA methodology. This study provides a feasible way of using SERS to elucidate the autophagy pathway induced by nanoparticles.

In this work, novel theranostic platforms based on graphene oxide and AuNP core polyaniline shell (GO-Au@PANI) nanocomposites are fabricated for simultaneous SERS imaging and chemo-photothermal therapy. PANI, a new NIR photothermal therapy agent with strong NIR absorption, outstanding stability and low cytotoxicity is decorated on AuNPs by one-pot oxidative polymerization, then the Au@PANI core-shell nanoparticles are attached to the graphene oxide (GO) sheet via π-π stacking and electrostatic interaction. The obtained GO-Au@PANI nanohybirds exhibit excellent NIR photothermal transduction efficiency and ultrahigh drug-loading capacity. The nanocomposites can also serve as novel NIR SERS probes utilizing the intense SERS signals of PANI. Rapid SERS imaging of cancer cells is achieved using this ultrasensitive nanoprobe. GO-Au@PANI also reveals good capability of drug delivery with the DOX-loading efficiency of 189.2% and sensitive NIR/pH-responsive DOX release. The intracellular real-time drug release dynamics from the nanocomposites is monitored by SERS-fluorescence dual mode imaging. Finally, chemo-photothermal ablation of cancer cells is carried out in vitro and in vivo using GO-Au@PANI as high-performance chemo-photothermal therapeutic nanoagent. The theranostic applications of GO-Au@PANI endow it with great potential for personalized and precise cancer medicine.

This study aimed to investigate the effect of electroacupuncture (EA) treatment through optical coherence tomography (OCT)in vivoon rats with adjuvant-induced arthritis. OCT images were obtained from the ankle of the right hind paws of the rats in control, model, and EA groups before modelling and 1 day, 8 days, 15 days, 22 days, and 29 days after modelling. Results demonstrated that the OCT signal of the ankle of the right hind paws of the rats was indistinct compared to 1 day after modelling and before modelling in the EA group. In the EA group, the light averaged attenuation coefficients of the ankle tissues decreased as treatment duration was prolonged after EA was administered (3.43, 2.96, 2.61, 2.42, and 2.29 mm−1, resp.). There was a significant difference in attenuation coefficient decrease between the 29th d and the 1st d for EA group compared with control group (P<0.01). This condition indicated that the light absorption of the ankle of the treated rats in the EA group decreased. Therefore, OCT can be used to monitor the effect of treatment on rats with arthritisin vivo.

Graphene oxide (GO) has immense potential applications in water purification and biomedical field. Recently, three-dimensional GO-based hydrogels have attracted great attention owing to their advantageous properties. However, it is quite difficult to develop highly efficient, low cost, broad spectrum antibacterial materials that can be easily recycled. In this experimental work, we used a facile one-pot method to synthesize two kinds of GO-based hydrogels: benzalkonium bromide/graphene oxide hydrogel (BKB/GOG) and benzalkonium bromide/polydopamine/reduced graphene oxide hydrogel (BKB/PDA/rGOG). The as-prepared three-dimensional hydrogels were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. The swelling degrees of BKB/GO xerogels and BKB/PDA/GO xerogels with different BKB concentrations were calculated. The maximum value of swelling degree was found to be 95.2 mg/mg. Owing to the synergistic effect of graphene oxide and benzalkonium bromide, the resultant hydrogels exhibited strong antibacterial activities against both Gram-negative and Gram-positive bacteria. The result of bacterial kinetic tests agreed well with that of the qualitative antibacterial experiments. The resultant hydrogels could be easily removed from the solution, which enhanced their potential use in industrial applications. The antibacterial effect of the hydrogel synthesized from benzalkonium chloride (BKC) and graphene oxide was investigated. The findings of this investigation can be beneficial in elucidating the mechanism of synthesis process that involves benzalkonium salts and graphene oxide.

A multifunctional nanoplatform based on black phosphorus quantum dots (BPQDs) was developed for cancer bioimaging and combined photothermal therapy (PTT) and photodynamic therapy (PDT). BPQDs were functionalized with PEG chains to achieve improved biocompatibility and physiological stability. The as-prepared nanoparticles exhibite prominent near-infrared (NIR) photothermal and red-light-triggered photodynamic properties. The combined therapeutic application of PEGylated BPQDs were then performed in vitro and in vivo. The results demonstrate that the combined phototherapy significantly promote the therapeutic efficacy of cancer treatment in comparison with PTT or PDT alone. BPQDs could also serve as the loading platform for fluorescent molecules, allowing reliable imaging of cancer cells. In addition, the low cytotoxicity and negligible side effects to main organs were observed in toxicity experiments. The theranostic characteristics of PEGylated BPQDs provide an uplifting potential for the future clinical applications.

In this work, we report a facile method using MoS2 quantum dots (QDs) as reducers to directly react with HAuCl4 for the synthesis of Au nanoparticle@MoS2 quantum dots (Au NP@MoS2 QDs) core@shell nanocomposites with an ultrathin shell of ca. 1 nm. The prepared Au NP@MoS2 QDs reveal high surface enhanced Raman scattering (SERS) performance regarding sensitivity as well as the satisfactory SERS reproducibility and stability. The limit of detection of the hybrids for crystal violet can reach 0.5 nM with a reasonable linear response range from 0.5 μM to 0.5 nM (R2 ≈ 0.974). Furthermore, the near-infrared SERS detection based on Au NP@MoS2 QDs in living cells is achieved with distinct Raman signals which are clearly assigned to the various cellular components. Meanwhile, the distinguishable SERS images are acquired from the 4T1 cells with the incubation of Au NP@MoS2 QDs. Consequently, the straightforward strategy of using Au NP@MoS2 QDs exhibits great potential as a superior SERS substrate for chemical and biological detection as well as bio-imaging.

Silver–graphene oxide (Ag–GO) nanocomposites were in situ fabricated rapidly through a green one-pot method by using tryptophan (Trp) as a reducing and stabilizing agent. The morphologies of synthesized Ag–GO nanocomposites were characterized by UV–vis absorption spectroscopy, transmission electron microscopy (TEM), and micro-Raman system. The results indicated silver nanoparticles (Ag NPs) with spherical size were well dispersed on the surface of graphene oxide (GO). The role of pH has been explored to obtain optimum reaction conditions during the growth process. Raman signals of GO were greatly enhanced after Ag NPs loaded on its surface. More importantly, the synthesized Ag–GO nanocomposites exhibited excellent surface-enhanced Raman scattering (SERS) activity as SERS substrates to detect crystal violet (CV) in aqueous solution, and the enhancement factor ( EF ) from the intensity of the vibrational mode at 1621 cm −1 was calculated to be 1.6 × 10 5 .

Herein, we used a facile method mainly through self-assemble, hydrogen bonding and electrostatic interaction to synthesize poly(diallyldimethylammonium chloride)/graphene oxide (PDDA/GO) hydrogels, which can be easily used as adsorbents to eliminate anionic dyes. The as-prepared PDDA/GO hydrogels were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. In order to research the adsorption kinetics for the removal of anion dyes from water pollution, we further investigated that the effect of concentration, temperature, pH, ionic strength or cycle number on the removal process. The results indicated that due to the strong π–π stacking and anion–cation interaction, there were high removal efficiencies for both ponceau S (PS) and trypan blue (TB). The equilibrium time of adsorption is 30 min and 120 min for PS and TB, respectively, at which the solution could be decolorized to nearly colorless. Meanwhile, the adsorption process was more according with the pseudo-second-order model than the pseudo-first-order model. The hydrogels exhibited high removal efficiency for those two anionic dyes after four repeated adsorption and desorption treatments. It was demonstrated that PDDA/GO hydrogels would have great potential as a freestanding and reusable adsorbent for the practical application in water purification.

Melanin plays an indispensable role in the human body. It serves as a biological reducer for the green synthesis of precious metal nanoparticles. Melanin-Ag nanocomposites were successfully produced which exhibited very strong surface-enhanced Raman scattering (SERS) effect because of the reducibility property of melanin. A melanin-Ag composite structure was synthesized in situ in melanin cells, and SERS technique was performed for the rapid imaging and quantitative assay of intracellular melanin. This imaging technique was also used to successfully trace the formation and secretion of intracellular melanin after stimulation with melanin-stimulating hormones. Based on the self-reducing property of melanin, the proposed SERS imaging method can provide potentially powerful analytical detection tools to study the biological functions of melanin and to prevent and cure melanin-related diseases.

Ascribe to the unique two-dimensional planar nanostructure with exceptional physical and chemical properties, black phosphorous (BP) as the emerging inorganic twodimensional nanomaterial with high biocompatibility and degradability has been becoming one of the most promising materials of great potentials in biomedicine. The exfoliated BP sheets possess ultra-high surface area available for valid bio-conjugation and molecular loading for chemotherapy. Utilizing the intrinsic near-infrared optical absorbance, BPbased photothermal therapy in vivo, photodynamic therapy and biomedical imaging has been realized, achieving unprecedented anti-tumor therapeutic efficacy in animal experiments. Additionally, the BP nanosheets can strongly react with oxygen and water, and finally degrade to non-toxic phosphate and phosphonate in the aqueous solution. This manuscript aimed to summarize the preliminary progresses on theranostic application of BP and its derivatives black phosphorus quantum dots (BPQDs), and discussed the prospects and the state-of-art unsolved critical issues of using BP-based material for theranostic applications.

Graphene has become an ideal substrate for surface-enhanced Raman scattering (SERS) to study the chemical enhancement mechanism. In comparison with mechanically exfoliated graphene, graphene oxide (GO) has been found to be a better substrate due to its highly negatively charged oxygen functional groups. In this work, the pH-dependent SERS effect of aromatic molecules on GO are investigated. The results demonstrate that the Raman enhancement of dyes deposited on GO performs differently over a wide range of pH values (2 to 10). Adsorption experiments show that the pH-dependent SERS effect is closely related to the adsorption of aromatic molecules on GO, which is dominated by the electrostatic interaction. Thus, the influence of pH in GO-mediated SERS should be carefully considered, especially in its biomedical application. Copyright © 2012 John Wiley & Sons, Ltd.

In this study, we report permeability coefficients of 30% glucose diffusion by the optical coherence tomography signal slope (OCTSS) method in four kinds of human lung tissue in vitro: normal lung tissue, benign granulomatosis lung tissue, squamous cell carcinoma and adenocarcinoma tumor. To quantify the permeability coefficient of the agent, the monitored region was 80 μm thickness at a tissue depth of ca 230 μm from the surface. The permeability coefficients of 30% glucose from 10 independent experiments were averaged and found to be (1.35 ± 0.13) × 10(-5) cm s(-1) from the normal lung tissue, (1.78 ± 0.21) × 10(-5) cm s(-1) from the benign granulomatosis lung tissue, (2.88 ± 0.19) × 10(-5) cm s(-1) from the adenocarcinoma tumor and (3.53 ± 0.25) × 10(-5) cm s(-1) from the squamous cell carcinoma, respectively. It could be clearly seen that the permeability coefficients of 30% glucose increase ca 32%, 113% and 162% in the benign granulomatosis, adenocarcinoma tumor and squamous cell carcinoma of human lung tissue compared with that from the normal lung tissue, respectively. Therefore, we inferred from this pilot study that the OCT imaging is a feasible method to distinguish normal and cancer lung tissue.

Oxidative bleaching changes of human teeth induced changes in the optical properties of dental tissue. We introduced 1310 nm wavelengths of optical coherence tomography (OCT) attenuation coefficient method which is a relatively novel and rarely reported methodology to measure the correlation coefficient during the teeth oxidative bleaching procedure. And the quantitative parameters of enamel optical thickness and disruption of the entrance signal (DES) were extracted from the OCT images. The attenuation coefficient of the bleached tissue is 6.2 mm−1 which is significant (p < 0.001) higher than that unbleached sample is 1.4 mm−1. But attenuation coefficient varied significantly (p < 0.001) between 5.9 and 1.5 mm−1 in dentine which is downtrend. Furthermore, the persistence of bleaching oxidation in 35% hydrogen peroxide-induced optical thickness of enamel is similar with unbleached tissue which may indicate the refractive index of enamel is unchanged. Moreover, disruption of the entrance signal (DES) analysis showed that remarkable difference was appeared at enamel surface. The results indicate that optical properties of oxidative bleaching human dental tissue can be determined by attenuation coefficient using OCT system.

It is necessary to develop a laboratory model to evaluate tooth discoloration, because there are several limitations to assessment methods at present stage. Therefore, in this letter, we report the results from a pilot study on using optical coherence tomography imaging method to quantify color alteration in the human teeth treatment with 35% hydrogen peroxide bleaching in vitro. Quantitative comparison of chromogens reduction in dental tissue showed that near infrared attenuation coefficient (μ) increased for enamel with the bleaching passage time and diminution for dentine. Therefore, the precise detection of the change in attenuation coefficient is can accurate quantitative chromogens alteration in tooth. OCT has a potential to become a useful tool for the assessment color alteration in human teeth.

The main objective of the present work is to study the influence of heat treatment on the esophageal cancer detection using the diffuse reflectance (DR) spectral intensity ratio R540/R575 of oxygenated hemoglobin (HbO2) absorption bands to distinguish the epithelial tissues of normal human esophagus and moderately differentiated esophageal squamous cell carcinoma (ESCC) at different heat treatment temperature of 20, 37, 42, 50, and 60°C, respectively. The DR spectra for the epithelial tissues of the normal esophagus and ESCC in vitro at different heat-treatment temperature in the wavelength range 400–650 nm were measured with a commercial optical fiber spectrometer. The results indicate that the average DR spectral intensity overall enhancement with concomitant increase of heat-treatment temperature for the epithelial tissues of normal esophagus and ESCC, but the average DR spectral intensity for the normal esophageal epithelial tissues is relatively higher than that for ESCC epithelial tissues at the same heat-treatment temperature. The mean R540/R575 ratios of ESCC epithelial tissues were always lower than that of normal esophageal epithelial tissues at the same temperature, and the mean R540/R575 ratios of the epithelial tissues of the normal esophagus and ESCC were decreasing with the increase of different heat-treatment temperatures. The differences in the mean R540/R575 ratios between the epithelial tissues of normal esophagus and ESCC were 13.33, 13.59, 11.76, and 11.11% at different heat-treatment temperature of 20, 37, 42, and 50°C, respectively. These results also indicate that the DR intensity ratio R540/R575 of the hemoglobin bands is a useful tool for discrimination between the epithelial tissues of normal esophagus and ESCC in the temperature range from room temperature to 50°C, but it was non-effective at 60°C or over 60°C.

The purpose of study is to quantify and compare diffusion of propylene glycol, glucose, glycerol in the human skin in vivo noninvasively. Optical coherence tomography (OCT) was utilized in the functional imaging of optical cleaning agents for monitoring and quantifying the permeability coefficients (PCs) of them. Our experiments showed that the permeability coefficient of 40% propylene glycol from different subjects was averaged and found to be (2.52 ± 0.02) × 10−6 cm/s, the permeability coefficient of 40% glucose was (1.94 ± 0.05) × 10−6 cm/s, and the permeability coefficient of 40% glycerol was (1.82 ± 0.04) × 10−6 cm/s. The results indicated that the diffusion of propylene glycol solutions was faster than that of glucose solution, and the diffusion of glucose solutions was faster than that of glycerol solutions. The dependence of the permeability on the different hyperosmotic analytes could potentially be used in various basic science and clinical fields, such as optical clearing of tissues and cells as well as in clinical pharmacology.

Oxygenated hemoglobin diffuse reflectance (DR) ratio (R540/R575) method based on DR spectral signatures is used for early diagnosis of malignant lesions of human gastric epithelial tissues in vitro. The DR spectra for four different kinds of gastric epithelial tissues were measured using a spectrometer with an integrating sphere detector in the spectral range from 400 to 650 nm. The results of measurement showed that the average DR spectral intensity for the epithelial tissues of normal stomach is higher than that for the epithelial tissues of chronic and malignant stomach and that for the epithelial tissues of chronic gastric ulcer is higher than that for the epithelial tissues of malignant stomach. The average DR spectra for four different kinds of gastric epithelial tissues show dips at 542 and 577 nm owing to absorption from oxygenated Hemoglobin (HbO2). The differences in the mean R540/R575 ratios of HbO2 bands are 6.84% between the epithelial tissues of normal stomach and chronic gastric ulcer, 14.7% between the epithelial tissues of normal stomach and poorly differentiated gastric adenocarcinoma and 22.6% between the epithelial tissues of normal stomach and undifferentiated gastric adenocarcinoma. It is evident from results that there were significant differences in the mean R540/R575 ratios of HbO2 bands for four different kinds of gastric epithelial tissues in vitro (P < 0.01).

Here we examined the effect of human normal breast (NB) and breast cancer (BC) tissues in vitro after treatment with glycerol in conjunction with ultrasound (surgeonperformed, SP) by OCT for functional imaging to monitor. 60% glycerol (G) and SP was simultaneously applied for 5 min. Depth- and time-resolved profiles for OCT signal enhancement were presented. The results show that OCT imaging depth of breast tissues after treatment with 60% G in combined with SP more obviously improved than that after application of glycerol alone. The permeability coefficient of 60% glycerol in 60% G/NB, 60% G/BC, 60% G/SP/NB, and 60% G/SP/BC were (0.91±0.02)×10-5 cm/s, (3.22±0.09)×10-5 cm/s, (1.63±0.04)×10-5 cm/s, and (7.98±0.19)×10-5 cm/s, respectively. The permeability coefficient of glycerol in 60% G/SP/NB was 1.84-fold than that in 60% G/NB, but there was 2.54-fold on permeability coefficient comparing 60% G/SP/BC with that in 60% G/BC. The results from this study indicated that the permeability coefficient of glycerol not only in normal breast tissues, but also in breast cancer tissues after treatment with ultrasound is larger than that in tissues without ultrasound.

Optical coherence tomography (OCT) holds great promise as a routine research tool for analysis of identifying the boundaries between normal and diseased breast tissue in vitro and in vivo. However, despite the depth penetration afforded by this imaging modality, light attenuation in tissues imposes limitations. Here we studied the optical clearing effect of glycerol in human cancer and normal breast tissues with OCT for functional imaging to monitor. Depth- and time-resolved profiles for OCT signal enhancement were presented. The results show that the OCT imaging depth and imaging contrast of breast tissues have been improved after application of 60% glycerol in the 2-D OCT images. The OCT slope signals of breast tissues decreased as glycerol diffusion into tissues, therefore, the water and intercellular fluids were drawn out from tissues. Then the reverse process due to water was drawn back into the cells as a result of its affinity for water. The permeability coefficient of 60% glycerol was (3.14±0.07)×10-5 cm/s in breast cancer tissues, and (0.89±0.02)×10-5 cm/s in normal breast tissues, respectively. The permeability coefficient of glycerol in cancer tissues was 3.54-fold than that in normal tissues. These results demonstrate that the optical clearing of normal and cancer breast tissues are improved after application of glycerol.

Graphene oxide (GO)/Ag nanoparticle (NP) hybrids are obtained by in situ reduction of Ag NPs on GO sheets. In this letter, the influence of the conformation of GO sheets on the surface-enhanced Raman scattering (SERS) effect of GO/Ag NPs is investigated by covalently grafting folic acid (FA) molecules onto graphite sheets. SERS measurements are conducted in aqueous solutions with different pH values. Data show that the SERS signals of FA are pH dependent, consistent with the morphological changes of GO sheets.

Recently, three-dimensional GO-based hydrogels have attracted great attention due to the unique advantages. It is generally know that bacteria are everywhere and many of them could cause the diseases and threaten human health. However, developing new antibacterial materials with high-efficiency, low cost, broad-spectrum, and easy recycling is still a great challenge. Herein, inspired by mussel, we synthesized benzalkonium bromide/polydopamine/reduced graphene oxide hydrogel (BKB/PDA/rGOG). The as-prepared three-dimensional hydrogels were characterized by scanning eletron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The resultant hydrogels exhibited strong antibacterial effects to both Gram-negative and Gram-positive bacteria due to the synergistic effect of graphene oxide and benzalkonium bromide. In addition, the resultant hydrogels could be removed easily from the resolution, which was undoubtedly good news for industry application.