Non-target profiling of bitumen-influenced waters for the identification of tracers unique to oil sands processed-affected water (OSPW) in the Athabasca watershed of Alberta, Canada.

RATIONALE: The objective of this study was to identify unique chemical tracers of oil sands process-affected water (OSPW) to enable definitive discrimination of tailings pond seepage from natural bitumen-influenced waters from the Canadian Alberta McMurray formation. METHODS: The approach involved comparing unknowns from an unprecedented sample set of OSPW (n = 4) and OSPW-affected groundwaters (n = 15) with natural bitumen-influenced groundwaters (n = 20), using high-performance liquid chromatography/electrospray ionisation high-resolution mass spectrometry (HPLC/ESI-HRMS) operated in both polarities. RESULTS: Four unknown chemical entities were identified as potential tracers of OSPW seepage and subsequently subjected to structural elucidation. One potential tracer, tentatively identified as a thiophene-containing carboxylic acid [C15 H23 O3 S]- , was only detected in OSPW and OSPW-affected samples, thereby showing the greatest diagnostic potential. The remaining three unknowns, postulated to be two thiochroman isomers [C17 H25 O3 S]+ and an ethyl-naphthalene isomer [C16 H21 ]+ , were detected in one and two background groundwaters, respectively. CONCLUSIONS: We advanced the state of knowledge for tracers of tailings seepage beyond heteroatomic classes, to identifying diagnostic substances, with structures postulated. Synthesis of the four proposed structures is recommended to enable structural confirmations. This research will guide and inform the Oil Sands Monitoring Program in its efforts to assess potential influences of oil sands development on the Athabasca River watershed.

Diselenide-Pemetrexed Assemblies for Combined Cancer Immuno-, Radio-, and Chemotherapies.

Immunotherapy has emerged as a promising new approach for cancer treatment. However, clinically available drugs have been limited until recently, and the antitumor efficacy of most cancer immunotherapies still needs to be improved. Herein, we develop diselenide-pemetrexed assemblies that combine natural killer (NK) cell-based cancer immunotherapy with radiotherapy and chemotherapy in a single system. The assemblies are prepared by co-assembly between pemetrexed and cytosine-containing diselenide through hydrogen bonds. Under γ-radiation, the hydrogen bonds are cleaved, resulting in the release of pemetrexed. At the same time, diselenide can be oxidized to seleninic acid, which suppresses the expression of human leukocyte antigen E (HLA-E) in cancer cells, thus activating the immune response of NK cells. In this way, cancer immunotherapy is combined with radiotherapy and chemotherapy, providing a new strategy for cancer treatment.

Toxicity in aquatic model species exposed to a temporal series of three different flowback and produced water samples collected from a horizontal hydraulically fractured well.

In the present study, we compared the toxicity and associated chemical characterizations of flowback and produced water (FPW) collected from a single horizontal hydraulically fractured well at different time points during FPW production. Since few studies on whole mixture toxicity related to FPW exist, our aims were to determine both overall toxicity of the FPW mixture in a suite of organisms (Daphnia magna, Lumbriculus variegatus, Danio rerio, and Oncorhynchus mykiss) and also determine if toxicity changes depending on variation in FPW chemical properties as a function of time sampled (1.33, 72, and 228 h FPW samples collected immediately post-well production onset were analyzed in current study). FPW chemical composition was determined via quadra-pole inductively coupled plasma - mass spectrometry/mass spectrometry (ICP-MS/MS), full-scan high performance liquid chromatography/Orbitrap mass spectrometry (HPLC/Orbitrap-MS), and gas chromatography-mass spectrometry (GC-MS). We observed that FPW sampled later in the production process contained higher ion and total dissolved solids concentrations, whereas the highest concentrations of dissolved organic compounds were observed in the earliest FPW sample analyzed. Toxicity associated with FPW exposure was deemed to be species-specific to a certain extent, but general trends revealed the earliest FPW sampled contained highest toxic potential. Accordingly, we theorize that although the saline conditions of FPW are the foremost toxicological drivers to freshwater organisms, dissolved organics associated with FPW significantly contribute to the overall toxicity of exposed organisms.

Developmental Toxicity of the Organic Fraction from Hydraulic Fracturing Flowback and Produced Waters to Early Life Stages of Zebrafish ( Danio rerio).

Hydraulic fracturing (HF) has emerged as a major recovery method of unconventional oil and gas reservoirs and concerns have been raised regarding the environmental impact of releases of Flowback and Produced Water (FPW) to aquatic ecosystems. To investigate potential effects of HF-FPW on fish embryo development, HF-FPW samples were collected from two different wells and the organic fractions were isolated from both aqueous and particle phases to eliminate the confounding effects of high salinity. Each organic extract was characterized by non-target analysis with HPLC-Orbitrap-MS, with targeted analysis for polycyclic aromatic hydrocarbons provided as markers of petroleum-affected water. The organic profiles differed between samples, including PAHs and alkyl PAHs, and major substances identified by non-target analysis included polyethylene glycols, alkyl ethoxylates, octylphenol ethoxylates, and other high molecular weight (C49-79) ethylene oxide polymeric material. Zebrafish embryos were exposed to various concentrations of FPW organic extracts to investigate acute (7-day) and developmental toxicity in early life stages. The acute toxicity (LD50) of the extracted FPW fractions ranged from 2.8× to 26× the original organic content. Each extracted FPW fraction significantly increased spinal malformation, pericardial edema, and delayed hatch in exposed embryos and altered the expression of a suite of target genes related to biotransformation, oxidative stress, and endocrine-mediation in developing zebrafish embryos. These results provide novel information on the variation of organic profiles and developmental toxicity among different sources and fractions of HF-FPWs.

Wavelength-Controlled Dynamic Metathesis: A Light-Driven Exchange Reaction between Disulfide and Diselenide Bonds.

Wavelength-controlled dynamic processes are mostly based on light-triggered isomerization or the cleavage/formation of molecular connections. Control over dynamic metathesis reactions by different light wavelengths, which would be useful in controllable dynamic chemistry, has rarely been studied. Taking advantage of the different bond energies of disulfide and diselenide bonds, we have developed a wavelength-driven exchange reaction between disulfides and diselenides, which underwent metathesis under UV light to produce Se-S bonds. When irradiated with visible light, the Se-S bonds were reversed back to those of the original reactants. The conversion of the exchange depends on the wavelength of the incident light. This light-driven metathesis chemistry was also applied to tune the mechanical properties of polymer materials. The visible-light-induced reverse reaction was compatible with reductant-catalyzed disulfide/diselenide metathesis, and could be utilized to develop a dissipative system with light as the energy input.

Characterization of Naphthenic Acids and Other Dissolved Organics in Natural Water from the Athabasca Oil Sands Region, Canada.

With growth of the Canadian oil sands industry, concerns have been raised about possible seepage of toxic oil sands process-affected water (OSPW) into the Athabasca River (AR). A sampling campaign in fall 2015 was undertaken to monitor for anthropogenic seepage while also considering natural sources. Naphthenic acids (NAs) and thousands of bitumen-derived organics were characterized in surface water, groundwater, and OSPW using a highly sensitive online solid phase extraction-HPLC-Orbitrap method. Elevated NA concentrations and bitumen-derived organics were detected in McLean Creek (30.1 µg/L) and Beaver Creek (190 µg/L), two tributaries that are physically impacted by tailings structures. This was suggestive of OSPW seepage, but conclusive differentiation of anthropogenic and natural sources remained difficult. High NA concentrations and bitumen-derived organics were also observed in natural water located far north of the industry, including exceedingly high concentrations in AR groundwater (A5w-GW, 2000 µg/L) and elevated concentration in a tributary river (Pierre River, 34.7 µg/L). Despite these evidence for both natural and anthropogenic seepage, no evidence of any bitumen-derived organics was detected at any location in AR mainstem surface water. The chemical significance of any bitumen-derived seepage to the AR was therefore minimal, and focused monitoring in tributaries will be valuable in the future.

Selenium-Doped Carbon Quantum Dots for Free-Radical Scavenging.

Heteroatom doping is an effective way to adjust the fluorescent properties of carbon quantum dots. However, selenium-doped carbon dots have rarely been reported, even though selenium has unique chemical properties such as redox-responsive properties owing to its special electronegativity. Herein, a facile and high-output strategy to fabricate selenium-doped carbon quantum dots (Se-CQDs) with green fluorescence (quantum yield 7.6 %) is developed through the hydrothermal treatment of selenocystine under mild conditions. Selenium heteroatoms endow the Se-CQDs with redox-dependent reversible fluorescence. Furthermore, free radicals such as . OH can be effectively scavenged by the Se-CQDs. Once Se-CQDs are internalized into cells, harmful high levels of reactive oxygen species (ROS) in the cells are decreased. This property makes the Se-CQDs capable of protecting biosystems from oxidative stress.

Identification of conjugated linoleic acid (CLA) isomers by silver ion-liquid chromatography/in-line ozonolysis/mass spectrometry (Ag+-LC/O3-MS).

A novel method for the identification of conjugated linoleic acid (CLA) isomers has been developed in which silver ion liquid chromatography is coupled to in-line ozonolysis/mass spectrometry (Ag(+)-LC/O3-MS). The mobile phase containing CLA isomers eluting from the Ag(+)-LC column flows through a length of gas-permeable tubing within an ozone rich environment. Ozone penetrating the tubing wall reacts with the conjugated double bonds forming ozonolysis product aldehydes. These, and their corresponding methanol loss fragment ions formed within the atmospheric pressure photoionization (APPI) source, were detected by in-line MS and used for the direct assignment of double bond positions. Assignment of positional isomers is based entirely on the two pairs of diagnostic ions seen in the in-line O3-MS mass spectra. In this way, de novo identification of CLA positional isomers, i.e. without requiring comparison to CLA standards, was achieved. The Ag(+)-LC/O3-MS method was applied to the analysis of CLA isomers in a commercial CLA supplement, milk fat, and the lipid extract from a Lactobacillus plantarum TMW1460 culture. The results demonstrate how Ag(+)-LC/O3-MS can be used for the direct and fast determination of CLA isomers at low concentrations and in complex lipid mixtures.

Persistent Cytotoxicity and Endocrine Activity in the First Oil Sands End-Pit Lake.

Oil sands process-affected water (OSPW) is a byproduct of bitumen extraction that has persistent toxicity owing to its complex mixture of organics. A prominent remediation strategy that involves aging OSPW in end-pit lakes and Base Mine Lake (BML) is the first full-scale test. Its effectiveness over the first 5 years was investigated here using real-time cell analysis, yeast estrogenic and androgenic screens (YES/YAS), and ultra-high-resolution mass spectrometry. HepG2 cytotoxicity per volume of BML organics extracted decreased with age; however, the toxic potency (i.e., toxicity per mass of extract) was not significantly different between years. This was consistent with mass spectral evidence showing no difference in chemical profiles, yet lower total abundance of organics in field-aged samples, suggestive that dilution explains the declining cytotoxicity in BML. The IC50's of BML extracts for YES/YAS antagonism were at environmental concentrations and were similar despite differences in field-age. Persistent YES/YAS antagonism and cytotoxicity were detected in experimental pond OSPW field-aged >20 years, and while organic acids were depleted here, non-acid chemical classes were enriched compared to BML, suggesting these contribute to persistent toxicity of aged OSPW. To avoid a legacy of contaminated sites, active water treatment may be required to accelerate detoxification of end-pit lakes.

A study of the ozonolysis of model lipids by electrospray ionization mass spectrometry.

RATIONALE: The ozonolysis of vegetable oils has been proposed as step to functionalise unsaturated lipids for the production of bio-based chemicals and materials. The observation of ozonolysis products by mass spectrometry will facilitate mechanistic studies that are essential for the further development of industrial processes based on lipid ozonolysis. METHODS: Ozonolysis of the model lipids methyl oleate and triolein was performed and samples were taken over a range of reaction times. Ozonlysis products were separated by normal and non-aqueous reversed-phase (NARP) liquid chromatography (LC) coupled to electrospray ionization (ESI) mass spectrometry (MS) and tandem mass spectrometry (MS/MS) using a hybrid quadrupole-time of flight instrument. Post-column addition of ammonium acetate solutions aided ionization. Volatile reaction products were observed using gas chromatography/electron impact mass spectrometry (GC/MS). RESULTS: Secondary ozonides, reaction intermediates and previously unreported high molecular weight product dimers were observed as intact molecular ammonium ion adducts under positive ESI. The main fragment ions obtained by MS/MS were from cleavage of the trioxolane group, loss of fatty acyl chain and fragmentation between n-8 and n-9 on the fatty acyl chain. The MS/MS spectra and exact mass measurements explain most of the ozonolysis reaction products. CONCLUSIONS: LC/MS, LC/MS/MS and GC/MS results demonstrate that the products from the ozonolysis of the model lipids methyl oleate and triolein are consistent with known ozonolysis reaction pathways. LC/MS techniques using non-aqueous chromatography have permitted the direct observation of mono-, di- and tri-1,2,4-triloxanes which are the secondary ozonides formed by the ozonolysis of triolein. It was also shown that intermediates formed during the ozonolysis of triolein can combine to form high molecular weight ozonide dimers.

Copper-Selenocysteine Quantum Dots for NIR-II Photothermally Enhanced Chemodynamic Therapy.

Chemodynamic therapy has been appealing for effective cancer treatment. Particularly, Fenton-like reactions catalyzed by Cu2+-based nanoparticles showed promising prospects. Herein, we fabricated copper-selenocysteine quantum dots (Cu-Sec QDs) with the majority of Cu+ by a facile and robust thermal titration process. No high temperature or pressure is needed for this synthetic route of QDs. The selenocysteine functioned as the reducing agent as well as the stabilizer, circumventing the poor water solubility and stability, leading to enhanced biocompatibility. The existence of Cu+ endowed the QDs the ability to catalyze the Fenton-like reaction without an extra reduction reaction of Cu2+ to Cu+. Moreover, the strong absorption in the near-infrared-II region (1000-1300 nm) of the final Cu-Sec QDs is in great favor of the chemodynamic therapy via the photothermally enhanced Fenton-like reaction. And the Cu-Sec QDs exhibited obvious cytotoxicity to various cancer cell lines. We believe that this facile and robust synthetic approach could open up another method for the fabrication of quantum dots toward the potential Fenton-like reaction-based applications in biological fields.

Side-Chain Selenium-Grafted Polymers Combining Antiangiogenesis Treatment with Photodynamic Therapy and Chemotherapy.

The abnormal tumor vasculature in solid tumors creates hypoxia and leads to compromising the delivery and anticancer efficiency of nanomedicine. Nanomaterials with intrinsic antiangiogenesis ability might normalize tumor vessels and improve the therapeutic effect of O2-related treatment like PDT. Herein, we designed and prepared ROS-responsive side-chain selenium-grafted polymers, which had potential antiangiogenic activity, as vehicles to load photodynamic therapeutic agent Ce6 and chemotherapeutic drug oridonin. Under NIR irradiation, the C-Se bonds on the side chain of polymers could be cleaved in the presence of 1O2 produced by Ce6 and further formed organic selenic acid through selenoxide elimination reaction. The generated seleninic acid could downregulate the expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-2 (MMP-2) to inhibit angiogenesis and further relieve hypoxia. The released oridonin could significantly increase the intracellular ROS concentration. Both could modulate cancer cells' microenvironment to reinforce PDT. Therefore, these nanomedicines could be a good candidate for synergistic treatments of antiangiogenesis treatment, PDT, and chemotherapy.

Diselenide-Linked Polymers under Sonication.

A series of Se-Se-linked polystyrenes have been synthesized and subjected to pulse sonication. Comprehensive investigations based on GPC measurements, derivatization experiments, and EPR spectroscopy verify the sonication-induced bond scission and metathesis of these polymeric diselenides. The metathesis kinetics and energy conversion efficiency by different stimuli including heating, light, and sonication are compared, which demonstrate that sonication can offer an alternative way to break the Se-Se bond and realize selective metathesis reactions between diselenide-linked polymers and small molecules. This fundamental study on sonochemistry of diselenide-centered polymers expands our knowledge of diselenide chemistry and mechanochemistry of dynamic covalent mechanophores, which may greatly advance the applications of diselenide-containing polymers.

Selenium-Containing Nanoparticles Combine the NK Cells Mediated Immunotherapy with Radiotherapy and Chemotherapy.

Considering the limited clinical benefits of individual approaches against malignancy, natural killer (NK) cell-mediated immunotherapy is increasingly utilized in combination with radiotherapy and target therapeutics. However, the interplay of targeted agents, immunotherapy, and radiotherapy is complex. An improved understanding of the effect of chemotherapy or radiotherapy on specific molecular pathways in immune cells would help to optimize the synergistic antitumor efficiency. In this study, the selenium-containing nanoparticles (NPs) could deliver the chemotherapeutic drug doxorubicin (DOX) to tumor sites by systemic administration. Radiation stimuli facilitate DOX release and enhance chemotherapy efficiency. Moreover, radiation could oxidize diselenide-containing NPs to seleninic acid, which have both synergistic antitumor effect and immunomodulatory activity through enhancing NK cells function. These results indicate that the selenium-containing NPs would be a potential approach to achieve simultaneous treatments of immunotherapy, chemotherapy, and radiotherapy by a simple but effective method.

Effects of chemical fractions from an oil sands end-pit lake on reproduction of fathead minnows.

Oil sands process-affected water (OSPW) is a byproduct of bitumen extraction in the surface-mining oil sands industry in Alberta, Canada. Organic compounds in OSPW can be acutely or chronically toxic to aquatic organisms, so part of a long-term strategy for remediation of OSPW is ageing of water in artificial lakes, termed end-pit lakes. BaseMine Lake (BML) is the first oil sands end-pit lake, commissioned in 2012. At the time of its establishment, an effects-directed analysis of BML-OSPW showed that naphthenic acids and polar organic chemical species containing sulfur or nitrogen contributed to its acute lethality. However, the chronic toxicity of these same chemical fractions has not yet been investigated. In this work, the short-term fathead minnow reproductive bioassay was used to assess endocrine-system effects of two fractions of BML-OSPW collected in 2015. One of the fractions (F1) contained predominantly naphthenic acids, while the other (F2) contained non-acidic polar organic chemical species. Exposure of minnows to F1 or F2 at concentrations equivalent to 25% (v/v) of the 2015 BML-OSPW sample (5-15% of the 2012 BML-OSPW sample) did not alter reproductive performance, fertilization success, or concentrations of sex steroids in female or male minnows. Additionally, there were no significant differences in fertility, hatching success, or incidence of morphological indices of embryos collected on day 7 or 14 from exposed breeding trios. However, exposure of male fathead minnow to 25% (v/v) intact 2015 BML-OSPW resulted in a significantly greater hepatosomatic index. Exposure of fathead minnow to refined fractions of dissolved organic chemicals in 2015 BML-OSPW, or a 25% (v/v) of the intact mixture did not affect fertility or fecundity as measured by use of the 21-day reproductive bioassay. These data will be useful in setting future threshold criteria for OSPW reclamation and treatment.

Understanding the effects of hydraulic fracturing flowback and produced water (FPW) to the aquatic invertebrate, Lumbriculus variegatus under various exposure regimes.

Hydraulic fracturing of horizontal wells is a cost effective means for extracting oil and gas from low permeability formations. Hydraulic fracturing often produces considerable volumes of flowback and produced water (FPW). FPW associated with hydraulic fracturing has been shown to be a complex, often brackish mixture containing a variety of anthropogenic and geogenic compounds. In the present study, the risk of FPW releases to aquatic systems was studied using the model benthic invertebrate, Lumbriculus variegatus and field-collected FPW from a fractured well in Alberta. Acute, chronic, and pulse toxicity were evaluated to better understand the implications of accidental FPW releases to aquatic environments. Although L.variegatus is thought to have a high tolerance to many stressors, acute toxicity was significant at low concentrations (i.e. high dilutions) of FPW (48 h LC50: 4-5%). Chronic toxicity (28 d)of FPW in this species was even more pronounced with LC50s (survival/reproduction) and EC50s (total mass) at dilutions as low as 0.22% FPW. Investigations evaluating pulse toxicity (6 h and 48 h exposure) showed a significant amount of latent mortality occurring when compared to the acute results. Additionally, causality in acute and chronic bioassays differed as acute toxicity appeared to be primarily driven by salinity, which was not the case for chronic toxicity, as other stressors appear to be important as well. The findings of this study show the importance of evaluating multiple exposure regimes, the complexity of FPW, and also shows the potential aquatic risk posed by FPW releases.

Nontarget profiling of organic compounds in a temporal series of hydraulic fracturing flowback and produced waters.

Hydraulic fracturing (HF) flowback and produced water (FPW) can be toxic to aquatic life but its chemical content is largely unknown, variable and complex. Seven FPW samples were collected from a HF operation in the Duvernay Formation (Alberta, Canada) over 30 days of flowback and characterized by a nontarget workflow based on high performance liquid chromatography - high resolution mass spectrometry (HRMS). A modified Kendrick mass defect plot and MS/MS spectral interpretation revealed seven series of homologues composed of ethylene oxide (i.e. -CH2CH2O-), among which a series of aldehydes was proposed as degradation products of polyethylene glycols, and two series of alkyl ethoxylate carboxylates could be proprietary HF additives. Many other ions were confidently assigned a formula by accurate mass measurement and were subsequently prioritized for identification by matching to records in ChemSpider and the US EPA's CompTox Chemistry Dashboard. Quaternary ammonium compounds, amine oxides, organophosphorous compounds, phthalate diesters and hydroxyquinoline were identified with high confidence by MS/MS spectra (Level 3), matching to reference spectra in MassBank (Level 2) or to authentic standards (Level 1). Temporal trends showed that most of the compounds declined in abundance over the first nine days of flowback, except for phthalate diesters and hydroxyquinoline that were still observed on Day 30 and had disappearance half-lives of 61 and 91 days, respectively. All the compounds followed first-order disappearance kinetics in flowback, except for polyoxygenated acids which followed second-order kinetics. This analysis and the workflow, based largely on public on-line databases, enabled profiling of complex organic compounds in HF-FPW, and will likely be useful for further understanding the toxicity and chemical fate of HF-FPW.

Selenoxide elimination manipulate the oxidative stress to improve the antitumor efficacy.

Selenoxide elimination reaction has been widely used in the field of organic synthesis. However, few studies have been conducted to apply this reaction in biodegradable nanomedicine. In this work, the selenoxide elimination reaction was used for cancer treatment via producing excess cellular reactive oxygen species (ROS) for the first time. The ß-seleno diesters and porphyrin derivates containing nanoparticle could be responsive to the intracellular ROS and produce acrylates through the elimination reaction. The acrylates would further deplete intracellular GSH in tumor cells and finally improved the anticancer activity in the mice tumor model. Different from traditional ROS-responsive nanomedicine, the elimination product of this reaction could regenerate cytotoxic ROS and specifically disturb the redox balance of tumor cells. This work would provide attractive avenues for the development of therapeutic strategies against cancer via synthesis of well-designed biodegradable polymers.

Assessment of impacts of diphenyl phosphate on groundwater and near-surface environments: Sorption and toxicity.

Wastewater recovered from hydraulic fracturing is referred to as flowback and produced water (FPW), and is often saline, contains numerous organic and inorganic constituents, and may pose threats to groundwater resources. Hundreds of spills of FPW have been reported to the Alberta Energy Regulator each year. Recently, samples of FPW derived from hydraulic fracturing of the Duvernay Formation, AB, were found to contain a previously unidentified class of aryl phosphates, including diphenyl phosphate (DPP), triphenyl phosphate (TPP), and others. Aryl phosphates are also used in a variety of other industries and their constituents can be found in flame retardants, plasticizers, lubricants, hydraulic fluids, and oxidizers. Many of these aryl phosphates break down into DPP. Therefore, it is important to determine the environmental fate and potential impact of DPP if spilled in the near-surface, as DPP is an emerging contaminant in soil and groundwater systems. This study was aimed at determining 1) the sorption behavior of DPP onto various surficial sediments collected within the Fox Creek, AB region, and 2) the toxicity of DPP toward aquatic ecosystems. We report that the sorption of DPP onto both clay-rich soils and sandy sediment was low compared to that of other aryl phosphates, with an average log KOC value of 2.30 ±â€¯0.42 (1σ). Therefore, the transport of DPP in groundwater would be rapid due to its low degree of sorption on surficial materials. We also determined the acute 96 h-LC50 of DPP on zebrafish embryos to be 50.0 ±â€¯7.1 mg/L. Su et al. (2014) studied the toxic effects of DPP and TPP on chicken embryonic hepatocytes and found that DPP had less cytotoxic effects than TPP but altered more gene transcripts. From the results our study, we infer that DPP may pose an environmental risk to aquatic ecosystems if released into the environment.

Diselenide-Containing Hyperbranched Polymer with Light-Induced Cytotoxicity.

A light-induced cytotoxicity system was fabricated using active diselenide/porphyrin-containing hyperbranched polymer aggregates in aqueous solution through emulsification. When the nanoparticles were irradiated with visible light, 1O2 was produced by the porphyrin photosensitizers in the system, which cleaved the diselenide bonds in the polymer chains and disassembled the nanosystem. Interestingly, the oxidized products exhibited cytotoxicity to the MDA-MB 231cell line without using extra anticancer drugs, which endowed the system with potential visible light-induced antitumor activity. In combination with photodynamic therapy, it is greatly anticipated that better anticancer efficacy can be achieved with this system.