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As one of the most widespread musculoskeletal diseases worldwide, intervertebral disc degeneration (IVDD) remains an intractable clinical problem. Currently, oxidative stress has been widely considered as a significant risk factor in the IVDD pathological changes, and targeting oxidative stress injury to improve the harsh microenvironment may provide a novel and promising strategy for disc repair. It is evident that spermidine (SPD) has the ability to attenuate oxidative stress across several disease models. However, limited research exists regarding its impact on oxidative stress within the intervertebral disc. Moreover, enhancing the local utilization rate of SPD holds great significance in IVDD management. This study aimed to develop an intelligent biodegradable mesoporous polydopamine (PDA) nanoplatform for sustained release of SPD. The obtained PDA nanoparticles with spherical morphology and mesoporous structure released loaded-therapeutic molecules under low pH and H 2 O 2 . Combined treatment with SPD loaded into PDA nanoparticles (SPD/PDA) resulted in better therapeutic potential than those with SPD alone on oxidative stress injury. Furthermore, both SPD and SPD/PDA could induce anti-inflammatory M2 macrophage polarization. Upon injection into degenerative IVDs, the SPD/PDA group achieved a good repair efficacy with a long-term therapeutic effect. These findings indicated that the synergized use of SPD with responsive drug delivery nanocarriers may steadily scavenge reactive oxygen species and provide an effective approach toward the treatment of IVDD., Competing Interests: Declaration of competing interest The authors declare that they have no competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Chemiluminescence (CL), especially commercialized CL immunoassay (CLIA), is normally performed within the eye-visible region of the spectrum by exploiting the electronic-transition-related emission of the molecule luminophore. Herein, dual-stabilizers-capped CdTe nanocrystals (NCs) is employed as a model of nanoparticulated luminophore to finely tune the CL color with superior color purity. Initialized by oxidizing the CdTe NCs with potassium periodate (KIO 4 ), intermediates of the reactive oxygen species (ROS) tend to charge CdTe NCs in both series-connection and parallel-connection routes and dominate the charge-transfer CL of CdTe NCs. The CdTe NCs/KIO 4 system can exhibit color-tunable CL with the maximum emission wavelength shifted from 694 nm to 801 nm, and the red-shift span is over 100 nm. Both PL and CL of each of the CdTe NCs are bandgap-engineered; the change in the NCs surface state via CL reaction enables CL of each of the CdTe NCs to be red-shifted for ∼20 nm to PL, while the change in the NCs surface state via labeling CdTe NCs to secondary-antibody (Ab 2 ) enables CL of the CdTe NCs-Ab 2 conjugates to be red-shifted for another ∼20 nm to bare CdTe NCs. The CL of CdTe753-Ab 2 /KIO 4 is ∼791 nm, which can perform near-infrared CL immunoassay and semi-automatically determined procalcitonin (PCT) on commercialized in vitro diagnosis (IVD) instruments.

Potential-selective electrochemiluminescence (ECL) with tunable maximum-emission-potential ranging from 0.95 to 0.30 V is achieved using AgInS 2 /ZnS nanocrystals, which is promising in the design of multiplexed bioassay on commercialized ECL setups. The model system AgInS 2 /ZnS/N 2 H 4 exhibits efficient ECL around 0.30 V and can be exploited for sensitive immunoassays with less electrochemical interference and crosstalk.

Recent work by our laboratory and others indicates that co-display of multiple antigens on protein-based nanoparticles may be key to induce cross-reactive antibodies that provide broad protection against disease. To reach the ultimate goal of a universal vaccine for seasonal influenza, a mosaic influenza nanoparticle vaccine (FluMos-v1) was developed for clinical trial (NCT04896086). FluMos-v1 is unique in that it is designed to co-display four recently circulating haemagglutinin (HA) strains; however, current vaccine analysis techniques are limited to nanoparticle population analysis, thus, are unable to determine the valency of an individual nanoparticle. For the first time, we demonstrate by total internal reflection fluorescence microscopy and supportive physical-chemical methods that the co-display of four antigens is indeed achieved in single nanoparticles. Additionally, we have determined percentages of multivalent (mosaic) nanoparticles with four, three, or two HA proteins. The integrated imaging and physicochemical methods we have developed for single nanoparticle multivalency will serve to further understand immunogenicity data from our current FluMos-v1 clinical trial., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

In this work, a potential-resolved electrochemiluminescence (ECL) multiplex immunoassay (MIA) was developed using zirconium-based metal-organic framework (MOF) nanoparticles with intense self-ECL as an anodic ECL tag and CdTe nanocrystals (NCs) as a cathodic ECL tag. ECL luminophore 5,5'-(anthracene-9,10-diyl)diisophthalic acid (H 4 ADIP) and coreactant hexamethylenetetramine (HMT) bound to zirconium nodes in the MOF, giving Zr-ADIP-HMT nanoparticles. Benefiting from the intrareticular charge transfer (ICT) between the oxidized ligands of H 4 ADIP and HMT via hydrogen bonds, the intense self-ECL from Zr-ADIP-HMT was applied to the potential-resolved ECL MIA without an exogenous anodic coreactant, which can eliminate detrimental effects of multiplex coreactants and anodic ECL emission from CdTe NCs. The ICT within Zr-ADIP-HMT nanoparticles could shorten the electron transport path and reduce the complexity of radical intermediate transport. The ECL intensity from Zr-ADIP-HMT was 18.6-fold that from the mixture of H 4 ADIP and HMT. In potential-resolved ECL MIA, two lung cancer biomarkers, carcinoembryonic antigen and neuron-specific enolase, were adopted as model analytes, with detection limits of 18 and 5.3 fg·mL -1 , respectively. The dual-ligand Zr-ADIP-HMT nanoparticles provide a proof of concept using ICT-based self-ECL luminophores for potential-resolved ECL MIAs with isolated coreactants.

Single-color electrochemiluminescence (ECL) of nanoparticles is normally achieved in a bandgap engineered route via passivating the nanoparticle surface. Herein, when linear mercaptoalkanoic acids are employed as the thiol-capping agent of unary Au nanoclusters (NCs), a single-stabilizer-capped strategy is proposed to achieve surface defect-involved and single-color ECL from the AuNCs with hydrazine (N 2 H 4 ) as the coreactant. The carbon skeleton of the linear mercaptoalkanoic acids exhibits important effects on the ECL of the AuNCs, and efficient oxidative-reductive ECL is achieved with 8-mercaptooctanoic acid (MOA), 11-mercaptoundecanoic acid (MUA), and 12-mercaptododecanoic acid (MDA) capped AuNCs, respectively. The ECL of these AuNCs not only exhibits similar ECL intensity-potential profiles with the same maximum emission potential of ∼1.20 V (vs Ag/AgCl), but also demonstrates almost identical spectral ECL profiles of the same maximum emission wavelength around 713 nm as well as the same fwhm of 64 nm. The ECL of AuNCs/N 2 H 4 is obviously red-shifted to the photoluminescence of AuNCs, which not only provides unambiguous evidence that bandgap-engineered ECL of these AuNCs is quenched but also manifests that the capping agent of linear mercaptoalkanoic acid is promising for the achievement of surface defect-involved and single-color ECL from AuNCs. The MUA capped AuNCs can be utilized as an ECL tag for a sensitive and selective immunoassay, which exhibits a broad linear range from 0.5 mU/mL to 1 U/mL with a low limit of detection of 0.1 mU/mL (S/N = 3) with CA125 as the model analyte. This work provides a promising alternative to the traditional surface-passivating strategy for the achievement of single-color ECL from nanoparticle luminophores.

The electrochemiluminescence (ECL) bioassay is prominently carried out with the involvement of the coreactant. To remove the detrimental effects of the coreactant on the ECL of luminophores, herein, a promising ECL immunoassay strategy with biocompatible nanoparticles as the luminophore is proposed, which involves directly and electrochemically oxidizing the luminophore methionine-capped Au (Met@Au) nanocrystals (NCs) without the participation of any coreactant. Met@Au NCs are a kind of n-type nanoparticles, and they can be electrochemically injected with valence band (VB) holes around +0.80 and +1.10 V (vs Ag/AgCl). The electrochemically injected exogenous VB hole can recombine with the endogenous conduction band electron of Met@Au NCs and eventually bring out two coreactant-free and near-infrared ECL processes around 0.80 V (ECL-1) and 1.10 V (ECL-2). The intensity of coreactant-free ECL is primarily determined by the electrochemical oxidation-induced hole-injection process. ECL-2 is considerably stronger than ECL-1 and can be exploited for determining the carcinoembryonic antigen (CEA) in a sandwich immunoassay procedure with a linear range from 0.1 to 50 pg/mL as well as a limit of detection of 0.03 pg/mL (S/N = 3).

Herein, low-triggering-potential (LTP) electrochemiluminescence (ECL) with an onset around 0.0 V (vs Ag/AgCl) is proposed with bovine serum albumin (BSA)-stabilized Au nanocrystals (BSA-AuNCs) as a luminophore and hydrazine hydrate (N 2 H 4 ) as a coreactant. The BSA-AuNCs/N 2 H 4 system can exhibit efficient LTP-ECL around 0.37 V with the luminophore of both monodispersed and surface-confined states. The LTP-ECL of BSA-AuNCs/N 2 H 4 is a kind of single-color emission with a maximum emission wavelength around 740 nm, which is obviously red-shifted for 80 nm from that of BSA-AuNCs PL, and indicates that the ECL is generated in a surface-defect-involved route instead of the band-gap-engineered route. Importantly, BSA-AuNCs can be utilized as ECL tags to perform sandwich-type immunoassays with acceptable sensitivity and selectivity, which exhibits a wide linear response for determining CA125 from 0.5 to 1000 mU/mL and a limit of detection of 0.05 mU/mL (S/N = 3).

The photoluminescence, electroluminescence, and electrochemiluminescence from nanocrystals (NCs) have been extensively exploited for both fundamental and applied investigation over two decades, while the understanding of chemiluminescence (CL) from NCs is still far from clear by now. Herein, a general route for triggering CL from NC luminophore is proposed by extensively exploiting the charge transfer between n-type NCs and oxidants. Oxidants, such as K 2 S 2 O 8 , H 2 O 2 , KMnO 4 , and NaClO, can chemically inject the hole onto the valence band (VB) of methionine-capped n-type AuNCs (Met@AuNCs) and enable the occurrence of efficient radiative-charge-recombination between the chemically injected exogenous VB hole and the pre-existed endogenous conduction band (CB) electron, which eventually results in single-color and defect-involved CL with the maximum emission wavelength around 824 nm. The CL of Met@AuNCs/oxidant is qualified for ultrasensitive CL immunoassay in a similar procedure to the biotin-avidin and magnetic separation involved commercial CL immunoassay and exhibits acceptable performance for linearly determining carcinoembryonic antigen from 50 pg/mL to 100 ng/mL with a limit of detection of 10 pg/mL (S/N = 3). This strategy provides a general route to develop nanoparticulate CL luminophores and might eventually enable CL multiplexing assay via extensively exploiting the CL of different wavebands.

All commercial chemiluminescence (CL) assays are conducted with either glow or flash CL of eye-visible waveband from chemical luminophores. Herein, glow and flash, as well as waveband adjustable CL from the same nanoparticle luminophore of thiol-capped CuInS 2 @ZnS nanocrystals (CIS@ZnS-Thiol), are proposed via extensively exploiting the differed redox nature of CL triggering reagents. Taking thiosalicylic acid (TSA) as the model thiol-capping agent, the electron-injection-initiated charge transfer between CIS@ZnS-TSA and reductant can bring out efficient glow CL while the hole-injection-initiated charge transfer between CIS@ZnS-TSA and oxidant can give off obvious flash CL under optimum conditions. The maximum emission wavelength for CL of CIS@ZnS-TSA is adjustable from 730 nm to 823 nm via employing different triggering agents. Promisingly, the coexistent reductant of N 2 H 4 ·H 2 O and oxidant of H 2 O 2 can be employed as dual triggering reagents to trigger eye-visible and highly efficient flash CL from CIS@ZnS-TSA. The maximum emission intensity for flash CL of CIS@ZnS-TSA/N 2 H 4 -H 2 O 2 is 101-fold greater than the glow CL of CIS@ZnS-TSA/N 2 H 4 and 22-fold greater than the flash CL of CIS@ZnS-TSA/H 2 O 2 , respectively. The flash CL from CIS@ZnS-TSA/N 2 H 4 -H 2 O 2 is qualified for highly sensitive and selective CL immunoassay in a commercialized typical procedure with the entire operating process manually terminated within 35 min.

In this study, the self-assembling strategy was used to synthesize a therapeutic and diagnostic nanosystem for tumor-triggered targeting dual-mode near-infrared fluorescence (NIRF)/magnetic resonance (MR) imaging and photodynamic therapy applications. This theranostic nanosystem was synthesized based on the self-assembling of the short peptide (PLGVRGRGDC) and the gadolinium chelator (diethylenetriamine pentaacetic acid) functionalized amphiphilic DSPE-PEG 2000 , followed by loading with the insoluble photosensitizer therapeutic agent chlorin e6 (Ce6). The formed theranostic nanosystem can accumulate in the matrix metalloproteinase 2 (MMP2) rich tumor sites guided by the enhanced permeability and retention effect and MMP2-substrate peptide (PLGVR) targeting. After PLGVR was hydrolyzed in the tumor microenvironment by MMP2, the nanosystem was actively taken up by tumor cells via Arg-Gly-Asp (RGD) peptide-mediated internalization. With the coexistence of gadolinium and Ce6, the formed nanosystem can be used for both NIRF/MR dual-mode imaging and photodynamic therapy. These tumor-triggered targeting self-assembled nanoparticles with low cytotoxicity and high endocytosis efficiency can efficiently induce A549 cancer cell apoptosis under laser irradiation. Meanwhile, they possessed enhanced tumor-targeted NIRF/MR imaging ability and efficiently inhibited tumor growth with minimal side effects in mice bearing A549 lung cancer. Therefore, these self-assembled theranostic nanoparticles may have great potential for cancer clinical diagnosis and therapy.

Electrochemiluminescence (ECL) is conventionally generated in either an annihilation or a coreactant route, and the overwhelming majority of ECL research is conducted in the coreactant route via oxidizing or reducing the coexisting coreactant and luminophore. The coreacant-free ECL generated via merely oxidizing the luminophore would break through the ceiling of coreactant ECL via excluding the detrimental effects of exogenous coreactant and dissolved oxygen. Herein, by exploiting the rich-electron nature of n-type nanocrystals (NCs), coreacant-free ECL is achieved via merely oxidizing 3-mercaptopropionic acid (MPA) and mercaptosuccinic acid (MSA) capped InP/ZnS NCs, i.e., InP/ZnS MPA-MSA . The electron-rich InP/ZnS MPA-MSA can be electrochemically injected with holes via two oxidative processes at around +0.75 and +1.37 V (vs Ag/AgCl), respectively, and the exogenous hole can directly combine the conduction band (CB) electron of InP/ZnS MPA-MSA , resulting in two coreactant-free ECL processes without employing any exogenous coreactant. The deprotonation process for the carboxyl group of the capping agents can provide a negatively charged surface to InP/ZnS MPA-MSA and enhance the coreactant-free ECL. The hole-injecting process at +1.37 is much stronger than that at +0.75 V and eventually enables an ∼2000-fold enhanced ECL at +1.37 V than that at +0.75 V. The ECL at +1.37 V can be utilized for coreactant-free ECL immunoassay with prostate-specific antigen (PSA) as analyte, which exhibits an acceptable linear response from 5 pg·mL -1 to 1 ng·mL -1 with a limit of detection of 0.3 pg·mL -1 . The coreactant-free ECL route would provide an alternative to both annihilation and coreactant routes, simplify the ECL assay procedure and deepening the ECL mechanism investigations.

Electrochemiluminescence (ECL) of low triggering potential is strongly anticipated for ECL assays with less inherent electrochemical interference and improved long-term stability of the working electrode. Herein, effects of the thiol capping agents and the states of luminophores, i.e., the thiol-capped CuInS 2 @ZnS nanocrystals (CuInS 2 @ZnS-Thiol), on the ECL triggering potential of CuInS 2 @ZnS-Thiol/N 2 H 4 ·H 2 O were explored on the Au working electrode. The thiol capping agent of glutathione (GSH) not only enabled CuInS 2 @ZnS-Thiol/N 2 H 4 ·H 2 O with the stronger oxidative-reduction ECL than other thiol capping agents but also demonstrated the largest shift for the ECL triggering potential of CuInS 2 @ZnS-Thiol/N 2 H 4 ·H 2 O upon changing the luminophores from the monodispersed state to the surface-confined state. CuInS 2 @ZnS-GSH/N 2 H 4 ·H 2 O exhibited an efficient oxidative-reduction ECL around 0.78 V (vs Ag/AgCl) with CuInS 2 @ZnS-GSH of the monodispersed state. Upon employing CuInS 2 @ZnS-GSH as the ECL tag and immobilizing them onto the Au working electrode, the oxidative-reduction ECL of CuInS 2 @ZnS-GSH/N 2 H 4 ·H 2 O was lowered to 0.32 V (vs Ag/AgCl), which was about 0.88 V lower than that of traditional Ru(bpy) 3 2+ /TPrA (typically ∼1.2 V, vs Ag/AgCl). The ECL of the CuInS 2 @ZnS-GSH/N 2 H 4 ·H 2 O system with the luminophore of both monodispersed and surface-confined states was spectrally identical to each other, indicating that this surface-confining strategy exhibited negligible effect on the excited state for the ECL of CuInS 2 @ZnS-GSH. A surface-confined ECL sensor around 0.32 V was fabricated with CuInS 2 @ZnS-GSH as a luminophore, which could sensitively and selectively determine the K-RAS gene from 1 to 500 pM with a limit of detection at 0.5 pmol L -1 (S/N = 3).

The overwhelming majority of commercially available chemiluminescence (CL) assays are conducted in the eye-visible region. Herein, a near-infrared (NIR) aqueous CL strategy was proposed with CuInS 2 @ZnS nanocrystals (CIS@ZnS NCs) as emitters. Hydrazine hydrate (N 2 H 4 ·H 2 O) could inject electrons into the conduction band of the CIS@ZnS NCs and simultaneously transformed to the intermediate radical N 2 H 3 • . N 2 H 3 • reduced dissolved oxygen (O 2 ) to O 2 -• , while the O 2 -• could inject holes into the valence band of the CIS@ZnS NCs. The recombination of electrons and holes at Cu + defects in CIS@ZnS NCs eventually yielded efficient NIR CL at around 824.1 nm, which is the longest waveband for NCs CL to the best of our knowledge. The NIR CL could be conveniently performed in the neutral aqueous medium (pH 7.0) with a quantum yield of 0.0155 Einstein/mol and was successfully employed for constructing a signal-off CL biosensor with ascorbic acid as the analyte as well as a signal-on CL biosensor for determining ascorbate oxidase, which indicates that this NIR CL system has a promising potential for bioassays in diverse ways.

We developed a near-infrared (NIR) electrochemiluminescence (ECL) immunosensor for sensitively and selectively determining carbohydrate antigen 125 (CA125) with toxic-element-free and environmental-friendly AgInS 2 /ZnS nanocrystals (NCs) as tags. The core/shell-structured AgInS 2 /ZnS NCs not only can be conveniently prepared via an aqueous synthetic procedure, but also has high photoluminescence quantum yield (PLQY) of up to 61.7%, highly monodispersed, water-soluble, and desired biological compatibility. As AgInS 2 /ZnS NCs can be oxidized via electrochemically injecting holes into their valence band at + 0.84 V, both the monodispersed AgInS 2 /ZnS NCs in solution and the surface-confined AgInS 2 /ZnS NCs immobilized in sandwich-typed immuno-complexes with CA125 as analyte can exhibit efficient oxidative-reduction ECL around 695 nm under physiological conditions with the presence of tri-n-propylamine (TPrA). The ECL intensity from the AgInS 2 /ZnS NCs immobilized in sandwich-typed immuno-complexes increases linearly and selectively with an increased concentration of CA125 from 5 × 10 -6 to 5 × 10 -3  U/mL, and limit of detection (LOD) was 1 × 10 -6  U/mL (S/N = 3). This reliable platform can provide an effective detection method in the early diagnosis and treatment of ovarian cancer.

Novel optical labels for biosensing in near-infrared (NIR) region (especially between 800 and 900 nm) are arousing much attention for higher penetrating capability, less scattering and lowered autofluorescent background. Herein, a water-soluble electrochemiluminophore with effective electrochemiluminescence (ECL) around 815 nm is developed via doping dual-stabilizers-capped CdTe nanocrystals (NCs) with Co 2+ species in a growth-doping way. The Co 2+ -doped CdTe NCs not only can preserve the highly-passivated surface states of dual-stabilizers-capped CdTe NCs, but also exhibit efficient red-shifted photoluminescence (PL) and ECL into the promising optical NIR window of 800-900 nm. A spectrum-based ultrasensitive NIR ECL immunosensor is consequently fabricated with the Co 2+ -doped CdTe NCs as tags for the first time, which can selectively and sensitively determine human carcinoembryonic antigen with a wide linearity range from 1 fg/mL to 10 pg/mL and a low limit of detection at 0.2 fg/mL (S/N = 3). This work opens a way to screen novel NIR electrochemiluminophore as well as to modulate the ECL performance of NCs via surface doping and engineering., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A dual-wavebands-resolved electrochemiluminescence (ECL) multiplexing immunoassay (MIA) was developed for simultaneously detecting alpha fetoprotein antigen (AFP) in greenish waveband with CdSe550 (λ max = 550 nm) nanocrystals (NCs) and carbohydrate antigen 125 (CA125) in near-infrared waveband with CdTe790 (λ max = 790 nm) NCs via one-pot ECL reaction, in which dichroic mirror works as a key part to reflect ECL from CdSe550 to one photomultiplier-tube (PMT) and transmit ECL from CdTe790 to the other PMT for dual-wavebands-resolved assay. The proposed ECL-MIA strategy was capable of simultaneously determining AFP with linearly response from 5 pg/mL to 5 ng/mL and limit of detection at 1 pg/mL, and CA125 with linearly response from 5 mU/mL to 1 U/mL and limit of detection at 1 mU/mL, with desired specificity and without obvious energy-transfer between ECL tags. The dichroic mirror assistant ECL setup is easy-to-assemble and convenient for the popularization of color-resolved multiplexing ECL assay., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Copper indium sulfide (CuInS 2 , CIS) nanocrystals (NCs) are a promising solution to the toxic issue of Cd- and Pb-based NCs. Herein, electrochemiluminescence (ECL) of CIS NCs in aqueous medium is investigated for the first time with l-glutathione and sodium citrate-stabilized water-soluble CIS/ZnS NCs as model. The CIS/ZnS NCs can be oxidized to hole-injected states via electrochemically injecting holes into valence band at 0.55 and 0.94 V (vs Ag/AgCl), respectively. The hole-injected state around 0.94 V can bring out efficient oxidative-reduction ECL with a similar color to Ru(bpy) 3 2+ in the presence of tri- n-propylamine (TPrA) and enable CIS/ZnS NCs promising ECL tags with l-glutathione as linker for labeling. The ECL of CIS/ZnS NCs/TPrA can be utilized to determine vascular endothelial growth factor (VEGF) from 0.10 to 1000 pM with the limit of detection at 0.050 pM (S/N = 3). Although the hole-injected state around 0.55 V is generated ahead of oxidation of TPrA and fails to bring out coreactant ECL, annihilation ECL proves that both hole-injected states generated, at 0.55 and 0.94 V, can be involved in electrochemical redox-induced radiative charge transfer by directly stepping CIS/ZnS NCs from electron-injecting potential to hole-injecting potential. CIS/ZnS NCs are promising nontoxic electrochemiluminophores with lowered ECL triggering potential around 0.55 V for less electrochemical interference upon the development of coreactant.

A spectrum-resolved dual-color electrochemiluminescence (ECL) immunoassay was designed and implemented to simultaneously detect carcinoembryonic antigen (CEA) and alpha fetoprotein (AFP) with CdTe (λ max = 776 nm) and CdSe (λ max = 550 nm) nanocrystals (NCs) as ECL tags. The CdTe and CdSe NCs were labeled with respective probe antibodies (Ab 2 ) of CEA and AFP, respectively, and then immobilized onto the working electrode surface via sandwich-type immunoreactions. Both CdTe and CdSe NCs within the NCs immunocomplexes can be electrochemically reduced and simultaneously give off monochromatic ECL emissions in the near-infrared and greenish regions, respectively, when (NH 4 ) 2 S 2 O 8 was used as a cathodic ECL coreactant. The ECL spectra of the two surface-confined NCs were well separated and had no cross energy-transfer interactions, which made the dual-color immunoassay highly selective and sensitive toward respective target analytes. With the proposed ECL biosensor, CEA and AFP were simultaneously detected and quantified with an extremely low detection limit of 1 pg/mL for CEA and 10 fg/mL for AFP, respectively. This work demonstrated the probability of performing multianalyte assays via a spectrum-resolved ECL strategy with improved sensitivity and signal-to-noise ratio as compared to NCs-based fluorescent multianalyte assays.

Conventional electrochemiluminescence (ECL) research has been performed by detecting the total photons (i.e., the ECL intensity). Herein, systematic spectral exploration on the ECL of dual-stabilizers-capped ternary CdZnSe nanocrystals (NCs) and its sensing application were carried out on a homemade ECL spectral acquiring system. The ternary CdZnSe NCs could be repeatedly injected with electrons via some electrochemical ways and then result in strong cathodic ECL with the coupling of ammonium persulfate. ECL spectrum of the CdZnSe NCs was almost identical to corresponding photoluminescence spectrum, indicating that the excited states of CdZnSe NCs in ECL were essentially the same as those in photoluminescence. Importantly, after being labeled to the probe antibody (Ab2) of α-fetal protein (AFP) antigen, the ternary NCs in the Ab2|NCs conjugates could preserve their ECL spectrum very well. A spectrum-based ECL immunoassay was consequently proposed with the CdZnSe NCs as ECL tags and AFP as target molecules. The limit of detection is 0.010 pg/mL, with a signal-to-noise (S/N) ratio of 3, indicating a sensitive ECL sensing strategy that was different from the conventional ones. This work might open a pathway to the spectrally resolved ECL analysis with even-higher S/N ratios than the fluorescent analysis.

Biorelated single-molecule detection (SMD) has been achieved typically by imaging the redox fluorescent labels and then determining each label one by one. Herein, we demonstrated that the capping agents (i.e., mercaptopropionic acid and sodium hexametaphosphate) can facilitate the electrochemical involved hole (or electron) injecting process and improve the stability of the dual-stabilizers-capped CdSe nanocrystals (NCs), so that the CdSe NCs could be electrochemically and repeatedly inspired to excited states by giving off electrochemiluminescence (ECL) in a cyclic pattern. With the CdSe NCs as ECL label and carcinoembryonic antigen (CEA) as target molecule, a convenient single-molecule immunoassay was proposed by simply detecting the ECL intensity of the dual-stabilizers-capped CdSe NCs in a sandwich-typed immune complex. The limit of detection is 0.10 fg/mL at S/N = 3, which corresponds to about 6-8 CEA molecules in 20 μL of serum sample. Importantly, the ECL spectra of both CdSe NCs and its conjugate with probe antigen in the immune complex were almost identical to the photoluminescence spectrum of bare CdSe NCs, indicating that all emissions were originated from the same excited species. The molecular-counting-free and ECL-based SMD might be a promising alternative to the fluorescent SMD.

The versatility of the fluorescent probes inspires us to design fluorescently traceable prodrugs, which enables tracking the drug delivery kinetics in living cells. Herein, we constructed a self-indicating nanoprodrug with two fluorescent moieties, an aggregation-induced emission molecule (tetraphenylethylene, TPE) and a luminant anticancer drug (doxorubicin, DOX), with a pH-responsive linker between them. Except when a low pH environment is encountered, an energy-transfer relay (ETR) occurs and inactivates the fluorescence of both, showing a dark background. Otherwise, the ETR would be interrupted and evoke a dual-color fluorogenic process, giving distinct fluorogenic read out. By observing the dual-color fluorogenic scenario, we captured the kinetics of the drug release process in living cells. Because the separated TPE and DOX are both fluorescent but have a distinct spectrum, by examining the spatiotemporal pattern of TPE and DOX, we were able to precisely disclose the drug-releasing site, the releasing time, the destinations of the carriers, and the executing site of the drugs at subcellular level. Furthermore, different intracellular drug release kinetics between free doxorubicin and its nanoformulations were also observed in a real-time manner.

This study is focused on the intracellular fate of poly(d,l-lactide-co-glycolide) (PLGA) particles with different surface coatings after cellular uptake, and their influence on the functions of human liver cancer cells (HepG2 cells). The PLGA particles coated with polyethyleneimine (PEI) and bovine serum albumin (BSA) with a similar diameter of ∼400 nm but different surface chemistry were prepared. The intracellular distribution of the PLGA particles was also largely dependent on their surface coatings. The PLGA-PEI particles were removed from cells by exocytosis with a slower rate compared to the PLGA-BSA particles. In general, uptake of both types of the PLGA particles did not cause apparent impedance on cell viability and cell cycle, but uptake of the PLGA-PEI particles did have certain influence on cell functions such as intracellular level of reactive oxygen species, cytoskeleton organization, cell migration, and secretion levels of triglyceride.

The development of electrochemiluminescence (ECL) emitters over a broad spectrum of wavelengths is anticipated for the multiplexed ECL sensing and diagnostic application. Herein, a facile dual-stabilizers-capped strategy was developed for synthesizing a series of water-soluble CdSe nanocrystals (NCs) with strong, bandgap engineered and monochromatic ECL emissions in greenish region. The linkage of surface cadmium atoms to the dual stabilizers, mercaptopropionic acid and sodium hexametaphosphate, not only can effectively remove the nonradiative surface state and deep surface trap of CdSe NCs for improved ECL efficiency and monochromaticity, but is also favorable for the electrochemical involved electron and hole injection processes for higher ECL intensity. ECL spectra of dual-stabilizers-capped CdSe NCs are narrow and much close to corresponding photoluminescence spectra, which indicates a series of bandgap engineered and monochromatic ECL emitters. The ECL signal of dual-stabilizers-capped CdSe NCs also shows acceptable accuracy and precision for the detection of dopamine concentration in the practical drug (dopamine hydrochloride injection)., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A sandwich-typed near-infrared (NIR) electrochemiluminescence (ECL) immunoassay was developed with dual-stabilizer-capped CdTe nanocrystals (NCs) as ECL labels and α fetoprotein antigen (AFP) as model protein. The dual-stabilizer-capped NIR CdTe NCs were promising ECL labels because of their NIR ECL emission of 800 nm, low anodic ECL potential of +0.85 V, and high biocompatibity, which can facilitate interference-free and highly sensitive ECL bioassays. Upon the immunorecognition of the immobilized AFP to its antibody labeled with dual-stabilizer-capped CdTe NCs, the proposed immunoassay displayed increasing ECL intensity, leading to a wide calibration range of 10.0 pg/mL to 80.0 ng/mL with a detection limit of 5.0 pg/mL [signal-to-noise ratio (S/N) = 3] without coupling any signal amplification procedures. The NIR ECL immunoassay for real samples displayed very similar results with those of Ru(bpy)(3)(2+) reagent kit based commercial ECL immunoassay, which not only proved for the efficiency of NIR ECL from dual-stabilizer-capped CdTe NCs but also paved the road for development of novel ECL emitters and corresponding reagent kits.

Although a multitude of promising anti-cancer drugs have been developed over the past 50 years, effective delivery of the drugs to diseased cells remains a challenge. Recently, nanoparticles have been used as drug delivery vehicles due to their high delivery efficiencies and the possibility to circumvent cellular drug resistance. However, the lack of biocompatibility and inability to engineer spatially addressable surfaces for multi-functional activity remains an obstacle to their widespread use. Here we present a novel drug carrier system based on self-assembled, spatially addressable DNA origami nanostructures that confronts these limitations. Doxorubicin, a well-known anti-cancer drug, was non-covalently attached to DNA origami nanostructures through intercalation. A high level of drug loading efficiency was achieved, and the complex exhibited prominent cytotoxicity not only to regular human breast adenocarcinoma cancer cells (MCF 7), but more importantly to doxorubicin-resistant cancer cells, inducing a remarkable reversal of phenotype resistance. With the DNA origami drug delivery vehicles, the cellular internalization of doxorubicin was increased, which contributed to the significant enhancement of cell-killing activity to doxorubicin-resistant MCF 7 cells. Presumably, the activity of doxorubicin-loaded DNA origami inhibits lysosomal acidification, resulting in cellular redistribution of the drug to action sites. Our results suggest that DNA origami has immense potential as an efficient, biocompatible drug carrier and delivery vehicle in the treatment of cancer.

In the present work, we demonstrated a simple and green synthesis route for shape-controlled ZnS nanocrystals, where only environmentally benign chemicals, namely sulfur, zinc oxide and olive oil, were employed. By controlling the experimental conditions, we were able to tune the band edge and trap state photoluminescences of ZnS nanocrystals and obtain pure excitonic photoluminescence that was rarely observed in literature. The trap state emission was derived from sulfur vacancies and would be eliminated when an excess of sulfur was used during the synthesis. Additionally, the morphology of ZnS nanocrystals could be tuned to appear like flowers, where the formation mechanism was systematically discussed., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Functionalization of nanostructures such as gold nanoparticles (AuNPs) with different biological molecules has many applications in biomedical imaging, clinical diagnosis and therapy. Researchers mostly employed AuNPs larger than 10 nm for different biological and medicinal applications in previous studies. Herein, we synthesized a novel small (2 nm) AuNPs, which were functionalized with the therapeutic peptide, PMI (p12), and a targeted peptide, CRGDK for selective binding to neuropilin-1(Nrp-1) receptors which overexpressed on the cancer cells and regulated the process of membrane receptor-mediated internalization. It was found that CRGDK peptides increased intracellular uptake of AuNPs compared to other surface conjugations quantified by ICP-MS. Interestingly, CRGDK functionalized AuNPs resulted in maximal binding interaction between the CRGDK peptide and targeted Nrp-1 receptor overexpressed on MDA-MB-321 cell surface, which improved the delivery of therapeutic P12 peptide inside targeted cells. Au@p12 + CRGDK nanoparticles indicated with highly effective cancer treatment by increasing p53 expression upregulated with intracellular enhanced p12 therapeutic peptide. These results have implications to design and functionalize different molecules onto AuNPs surfaces to make hybrid model system for selective target binding as well as therapeutic effects for cancer treatment., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Magnetic metal (Mn, Fe, Co, and Ni) oxides nanocrystals with small size and uniform size distribution are synthesized via a cation-exchange reaction. Two experimental stages are included in the synthesis of metal oxides nanocrystals. Firstly, Cu(OH)2 decomposes to CuO nanocrystals, induced by free metal cations. Compared to CuO nanocrystals produced without any free metal cation, the free metal cation has an important influence on the shape and size of CuO. Secondly, free metal cations exchange with the Cu2+ cation in the CuO nanocrystals to get Mn3O4, Fe2O3, CoO and NiO nanocrystals by cation-exchange reactions. The magnetic properties of these metal oxides nanocrystals have been investigated, all the nanocrystals are superparamagnetic at room temperature.

SnS nanocrystals have been synthesized in a simple and facile way. Sn(6)O(4)(OH)(4) is introduced to synthesize tin sulfide, which is used as tin precursor. By changing the reaction conditions (reaction temperature and Sn/S molar ratio), SnS nanocrystals with different shape and size can be produced. SnS nanoparticles and nanoflowers with orthorhombic crystal structure have uniform size distribution. The SnS nanoflowers firstly transform to polycrystalline nanoflowers, and then become amorphous nanosheets. The drive force of amorphization reduces the high free-energy of nanocrystals. The layered crystal structure of SnS is the main reason for the shape evolution and amorphization processes. The optical properties of nanoparticles are investigated by optical absorption spectra. The optical direct band gap and optical indirect band gap in SnS nanoparticles are 3.6 eV and 1.6 eV, respectively. Compared to direct band gap (1.3 eV) and indirect band gap (1.09 eV) in bulk SnS, both direct transition and indirect transition in nanoparticles show an obvious quantum-size effect.

We report on a Raman study of nanocrystalline GaN with the wurtzite structure synthesized by arc plasma method. Resonant Raman scattering is observed using 514.5 nm (2.41 eV) laser excitation, which is near the band gap of the "yellow band" (2.2-2.3 eV). Under such near-resonant excitation, new Raman bands unexpected in an ideal wurtzite GaN crystal were found. The transverse optical modes of A[sub 1] (531 cm[sup -1]) and E[sub 1] (560 cm[sup -1]), and the nonpolar modes of E[sub 2] [567 cm[sup-1] (high) and 143 cm[sup -1] (low)] normally observed in bulk crystals, were recorded and were observed to be resonantly enhanced. Two new bands (680 and 344 cm[sup -1]) were assigned to the inactive optical phonon modes B[sub 1] (high) and B[sub 1] (low), respectively. A broadband centered at 710 cm[sup -1] was attributed to surface modes of the nanocrystals, providing good agreement with the calculated result based on Fröhlich theory. As a result of this study, Raman scattering of GaN nanocrystals has been characterized. [ABSTRACT FROM AUTHOR]

Photoluminescence and Raman spectra of ZnO single-crystal nanosheets have been studied as a function of applied hydrostatic pressure using the diamond-anvil-cell technique at room temperature. The ZnO nanosheets synthesized via a vapor transport process have uniform plane surfaces with lateral dimensions up to several microns and thickness of ∼100 nm. In terms of Raman results, the ZnO nanosheets underwent a transition from wurtzite to rock-salt structure with an increase of pressure, and the phase-transition pressure was measured to be about 11.2 GPa. However, a strong near-band-edge UV emission of ZnO nanosheets was observed with the applied pressure up to 20.0 GPa. Simultaneously, the emission peak shifted to higher-energy side with increasing pressure. By examining the dependence of the near-band-edge emission peak on the applied pressure, the pressure coefficient of the direct Γ band gap in the wurtzite ZnO nanosheets was determined. [ABSTRACT FROM AUTHOR]

Nano brazing of Pt-Ag nanoparticles with nano Ag filler metal is reported in this letter, which presents an effective way to join nanoobjects by femtosecond laser irradiation. The nano brazed interface between Pt-Ag and Ag showed good lattice matching along (111)Ag//(111)Ag-Pt. Lattice mismatch can hardly be observed at the interface between the filler metal and Pt-Ag nanoparticle, which is important for the joint strength and normally does not occur during joining. The very low mismatch also suggested that melting and solidification occurred during nano brazing by femtosecond laser. The role of Brownian motion on the nano joining process is also discussed in this paper. [ABSTRACT FROM AUTHOR]