Spin Trapping Research Articles

Influence of antioxidants in biodiesel degradation: Electronic paramagnetic resonance tracking of free radicals

Biodiesel is considered a renewable fuel that has been replacing diesel. However, its degradation, caused by a radical reaction, is one of the biggest concerns about this fuel. Spin trapping is a useful resource to evaluate the radical formation in a sample. In the present work, the biodiesel degradation from canola, corn and soybean oils, with synthetic antioxidants (BHA -butylated hydroxyanisole; BHT- butylated hydroxytoluene; TBHQ- tert-butylhydroquinone) and extracts (rosemary; oregano; basil), were measured by Electron Paramagnetic Resonance (EPR). The measurements were performed at room temperature, applying the spin trapping technique, using the α-phenyl-N-tert-butylnitrone (PBN) as the spin trap. The analyzed data allowed evaluating the degradation of the samples and their stability. Besides, the presence of the hydroxyl radical in all samples in the degradation process was identified. The biodiesel from soybean oil presented the greatest stability compared to the others, with all antioxidants tested. The oregano extract proved to be the most efficient natural antioxidant in the canola and soybean biodiesel, with more than 300 days of free radical detection, while the rosemary extract was more efficient in the corn biodiesel, achieving free radical signals until the 209th day of analysis.

The Nitrone Spin Trap DMPO Prevents Lipopolysaccharide-induced Pro-inflammatory Programming of Macrophages

The Nitrone Spin Trap DMPO Prevents Lipopolysaccharide-induced Pro-inflammatory Programming of Macrophages

Acute ischemic stroke induces magnetic resonance susceptibility signs dominated by endothelial nitric oxide synthase activation.

Acute ischemic stroke induces deoxyhemoglobin accumulation around the ischemic region while activating endothelial nitric oxide synthase (eNOS) coupling and the subsequent release of nitric oxide (NO). Because deoxyhemoglobin is a natural NO spin trap, its interplay with NO could be prominent during acute stroke. Its interaction with NO has been shown to induce overt paramagnetic signals in vitro; our goal was to investigate whether this interplay can be detected using MRI. To verify the in vivo image effects using the deoxyhemoglobin-NO interaction during acute stroke, eNOS states were manipulated in an animal model of acute ischemia, and the susceptibility signals, cerebral perfusion, and infarction were assessed noninvasively via MR susceptibility weighted imaging (SWI). Occlusion of the right middle cerebral artery increased eNOS coupling and susceptibility signals in the ischemic cortex while abolishing regional cerebral blood flow. Pharmacological eNOS blockage led to weakened susceptibility signals in the ischemic cortex as well as worsened tissue survival. Consistently, abolishment of eNOS coupling through genetic editing reduced the regional susceptibility signals in the ischemic cortex, causing large infarcts. Upregulation of eNOS during acute ischemia sustains tissue viability through the interaction between NO and deoxyhemoglobin. This interplay can be traced in vivo using SWI and can be considered a sensitive marker revealing the delicate oxygenation status of the ischemic tissue, therefore, guiding the management of acute stroke in clinical settings.

Turning Waste into Useful Products by Photocatalysis with Nanocrystalline TiO2 Thin Films: Reductive Cleavage of Azo Bond in the Presence of Aqueous Formate.

UV-photoexcitation of TiO2 in contact with aqueous solutions of azo dyes does not imply only its photocatalytic degradation, but the reaction fate of the dye depends on the experimental conditions. In fact, we demonstrate that the presence of sodium formate is the switch from a degradative pathway of the dye to its transformation into useful products. Laser flash photolysis experiments show that charge separation is extremely long lived in nanostructured TiO2 thin films, making them suitable to drive both oxidation and reduction reactions. ESR spin trapping and photoluminescence experiments demonstrate that formate anions are very efficient in intercepting holes, thereby inhibiting OH radicals formation. Under these conditions, electrons promoted in the conduction band of TiO2 and protons deriving from the oxidation of formate on photogenerated holes lead to the reductive cleavage of N=N bonds with formation and accumulation of reduced intermediates. Negative ion ESI–MS findings provide clear support to point out this new mechanism. This study provides a facile solution for realizing together wastewater purification and photocatalytic conversion of a waste (discharged dye) into useful products (such as sulfanilic acid used again for synthesis of new azo dyes). Moreover, the use of TiO2 deposited on an FTO (Fluorine Tin Oxide) glass circumvents all the difficulties related to the use of slurries. The obtained photocatalyst is easy to handle and to recover and shows an excellent stability allowing complete recyclability.

Tailoring the RhB removal rate by modifying the PVDF membrane surface through ZnO particles deposition

In this work, PVDF membranes coated with ZnO particles were prepared to study the influence of the loading concentration on RhB pollutant removal. The PVDF membranes prepared by phase inversion method contain a mixture of α and β phases as identified by correlating the XRD and FT-IR results. The mean pore size evaluated by SEM measurements is about 4 μm and the asymmetric structure of the membrane was highlighted. The presence of ZnO particles on PVDF membrane was evidenced by XRD, SEM and EXD measurements. By coating with ZnO particles the hydrophilic character of the membrane was improved. The RhB removal was realized using a combined process of two competitive methods: adsorption and photocatalysis. By increasing the ZnO loading the removal efficiency was enhanced. Additionally, the electron spin resonance spectroscopy coupled with spin trapping technique was used to evidence the generation of reactive oxygen species during irradiation, the presence of both hydroxyl radical and superoxide radical being proven.

The Non-innocent Role of Spin Traps in Monitoring Radical Formation in Copper-Catalyzed Reactions

Spin traps, like 5,5-dimethyl-1-pyrroline N-oxide (DMPO), are commonly used to identify radicals formed in numerous chemical and biological systems, many of which contain metal-ion complexes. In this study, continuous wave electron paramagnetic resonance and hyperfine spectroscopy are used to prove the equatorial ligation of DMPO(-derived) molecules to Cu(II), even in the presence of competing nitrogen bases. The experimental data are corroborated with density functional theory calculations. It is shown that 14N HYSCORE can be used as a fingerprint method to reveal the coordination of DMPO(-derived) molecules to Cu(II), an interaction that might influence the outcome of spin-trapping experiments and consequently the conclusion drawn on the mechanism under study.

Novel ionic liquid modified carbon nitride fabricated by in situ pyrolysis of 1-butyl-3-methylimidazolium cyanamide to improve electronic structure for efficiently degradation of bisphenol A

For this study, ionic liquid-modified carbon nitride (hm-CN) was one-step synthesized by 1-butyl-3-methylimidazolium cyanamide and carbon nitride (g-C3N4). After the addition of ionic liquids, the structural change of hm-CN increases the separation of photogenerated electron holes and improves the photocatalytic performance. The colorless pollutant bisphenol A (BPA) is degraded as the target pollutant under the visible light irradiation. The catalytic performance of g-C3N4 modified by ionic liquid is better than pure g-C3N4. The best performance is 30hm-CN, which degrades 95% of the pollutants in 3 hours. Its degradation performance is 4.5 times that of pure g-C3N4 and the degradation performance is still excellent after three cycles. According to electron spin resonance (ESR) and trapping experiments, h+ and •O2− play a key role in the photocatalytic degradation process. In addition, we conducted a series of condition experiments to perform degradation under different catalyst concentrations, different ions and different pH to fully understand the impact of external interference on the catalyst. At the same time, the sample also has good activity in degrading other pollutants (Rhodamine B, Methylene blue, Tetracycline, Ciprofloxacin). This study simply designed a method to synthesize ionic liquid modified g-C3N4 for improving photocatalytic performance, and provided a new idea for the research of carbon nitride modification at the same time.

SnS2-In2S3 p-n heterostructures with enhanced Cr6+ reduction under visible-light irradiation

We present one-pot hydrothemal syntheis of SnS2-In2S3 p-n heterostructures for photocatalytic reduction of Cr6+ to Cr3+. The conduction bands of In2S3 and SnS2 serve as the photogenerated electron donors and acceptors, respectively, forming a p-n junction band alignment improving the photogenerated charge separation efficiency. Through a detailed investigation of photocurrent spectra, photoluminescence spectra and electrochemical impedance, the heterojunction formation is shown to enhance the photogenerated charge separation and transport properties. In addition, the analysis of 5,5-Dimethyl-1-pyrroline N-oxide (DMPO) spin trapping electron spin resonance (ESR) spectra and band structure further testify the p-n junction of the composite catalyst that could accelerate the electron transport and change the pathway of photocatalytic process toward Cr6+ reduction. Furthermore, SnS2-In2S3 heterojunction photocatalyst achieved 3 times and 67 times higher efficiency than pure In2S3 and SnS2 photocatalysts under visible light toward Cr6+ reduction. Moreover, the SnS2-In2S3 p-n heterojunction photocatalyst demonstrates Cr6+ removal in a weak alkaline solution, breaking through the challenge of Cr6+ reduction in an alkaline environment.

Detection and identification of ethanal-derived spin-trapped free radicals using headspace thermal desorption gas chromatography-mass spectrometry (TD-GC-MS)

In this study, we demonstrate a novel approach to the detection and identification of the products of spin-trapped free radicals. Hydroxyl free radicals were generated by Fenton-based chemistry in the presence of ethanal and the spin-trapping agent N-tert-butyl-α-phenylnitrone (PBN). The resulting volatile compounds present in the reaction vial headspace were collected using thermal desorption (TD) and analysed by gas chromatography-mass spectrometry (GC-MS). Eleven compounds were detected in the headspace, and their identification was aided by using either a fluorinated or deuterated analogue of PBN as an alternative spin trap and/or deuterated ethanal (CD3CHO) as the secondary source of free radicals. The electron-ionisation (EI) mass spectra clearly demonstrate the “capture” of methyl radicals; two of the compounds detected were identified as containing one methyl group derived from ethanal, and four were shown to contain two methyl groups. This study demonstrates that sampling the reaction headspace using TD-GC-MS is a viable method for analysing products of free radical trapping, and potentially may be applied to a wide range of free radical systems.

Investigation of kinetics and mechanism for the degradation of antibiotic norfloxacin in wastewater by UV/H2O2

• Inhibition effect order of cations: Cu 2+ > Ca 2+ > Mg 2+ • Inhibition effect order of anions: CO 3 2− > NO 3 − > SO 4 2− • ROS contribution rate order: •OH (72.56%) > 1 O 2 (24.24%) > other ROS (3.20%) • The active sites of norfloxacin in UV/H 2 O 2 degradation were the piperazine ring and F atom • Binding free energy of DNA gyrase A: norfloxacin (-11.8 kJ/mol) > P1 (-12.8 kJ/mol) This study investigates the degradation of norfloxacin by using UV combined with hydrogen peroxide (UV/H 2 O 2 ) with different cations and anions. The inhibition effect order of cations for degradation of norfloxacin was Cu 2+ > Ca 2+ > Mg 2+ , attributed to the forms of the coordination compounds between norfloxacin and the cations. The inhibition effect order of anions for degradation of norfloxacin was CO 3 2− > NO 3 − > SO 4 2− , attributed to the ability and efficiency of the anions to quench ·OH or H 2 O 2 . The order of the reactive oxygen species (ROS) contribution rate to the degradation of norfloxacin under UV/H 2 O 2 was ·OH (72.56%) > 1 O 2 (24.24%) > other ROS (3.20%) based on the trapping experiments and electron spin resonance (ESR) measurements. There were at least 8 kinds of intermediate products, with charge-to-mass ratio ( m/z ) of 294, 267, 333a, 333b, 347, 335, 351 and 317, which were formed by attacks at the piperazine ring and F atom active sites. The F atom was replaced with -OH via a substitution reaction, resulting in P1 ( m/z = 317) formation. The inhibition effect of P1 on DNA gyrase A was stronger than that of norfloxacin due to the binding free energy (the binding free energy of P1-DNA gyrase A was -12.8457 kJ/mol, and the binding free energy of norfloxacin-DNA gyrase A was -11.8488 kJ/mol).

Specific features of radical generation in the reaction of thiols with hydrogen peroxide

Using the method of inhibitors it was found that the reduction of H2O2 with natural thiols in aqueous solutions is accompanied by the formation of radicals. The reaction of the nitroxyl radical TEMPO with glutathione (GSH) and H2O2 was studied together and separately. It allowed us to determine the optimal conditions for using the spin trap method in the presence of thiols. In the case of 5,5′-dimethyl-1-pyrroline N-oxide the reaction of GSH and synthetic thiol N-acetylcysteine with hydrogen peroxide at pH < 7 leads to the formation of thiyl and hydroxyl radicals.

Au-Cu@PANI Alloy Core Shells for Aerobic Fibrin Degradation under Visible Light Exposure.

Fibrin plays a critical role in wound healing and hemostasis, yet it is also the main case of cardiovascular diseases and thrombosis. Here, we show the unique design of Au-Cu@PANI alloy core-shell rods for fibrin clot degradation. Microscopic (transmission electron microscopy (TEM), scanning transmission electron microscopy-energy-dispersive X-ray (STEM-EDX)) and structural characterizations (powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS)) of the Au-Cu@PANI hybrid material reveal the formation of Au-Cu heterogeneous alloy core rods (aspect ratio = 3.7) with thin Cu2O and PANI shells that create a positive surface charge (ζ-potential = +22 mV). This architecture is supported by the survey XPS spectrum showing the presence of Cu 2p, N 1s, and C 1s features with binding energies of 934.8, 399.7, and 284.8 eV, respectively. Upon photolysis (λ ≥ 495 or 590 nm), these hybrid composite nanorods provide sufficient excited-state redox potential to generate reactive oxygen species (ROS) for degradation of model fibrin clots within 5-7 h. Detailed scanning electron microscopy (SEM) analysis of the fibrin network shows significant morphology modification including formation of large voids and strand termini, indicating degradation of fibrin protofibril by Au-Cu@PANI. The dye 1,3-diphenylisobenzofuran (DPBF) used to detect the presence of 1O2 shows a 27% bleaching of the absorption at λ = 418 nm within 75 min of irradiation of an aqueous Au-Cu@PANI solution in air. Moreover, electron paramagnetic resonance (EPR) spin-trapping experiments reveal a hyperfine-coupled triplet signature at room temperature with intensities 1:1:1: and g-value = 2.0057, characteristic of the reaction between the spin probe 4-Oxo-TEMP and 1O2 during irradiation. Controlled 1O2 scavenging experiments by NaN3 show 82% reduction in the spin-trapped EPR signal area. Both DPBF bleaching and EPR spin trapping indicate that in situ generated 1O2 is responsible for fibrin strand scission. This unique nanomaterial function via use of ubiquitous oxygen as a reagent could open creative avenues for future in vivo biomedical applications to treat fibrin clot diseases.

ESR spin trapping for in situ detection of radicals involved in the early stages of lipid oxidation of dried microencapsulated oils

Different studies have shown that detection of free radicals by ESR spin trapping provides useful information on the susceptibility to oxidation of bulk oils and accordingly on the oxidative stability of different samples for comparative purposes. With the same goal, ESR spin trapping was evaluated in this work for in situ detection of radicals in dried microencapsulated oils (DMOs). By testing different oils, encapsulation matrices and oxidation conditions, results showed that ESR spin trapping can be useful to evaluate the oxidative susceptibility of DMOs, but ESR data should be interpreted cautiously, as the great complexity of the reactions involved may lead to data misinterpretations. Conditions for oxygen availability can have important impacts on the rates of both spin trapping and spin-adduct quenching affecting the levels of radicals observed. The kinetics of oxidation, spin trapping and spin-adduct decay should be known first in bulk oils for correct data interpretation in DMOs.

•BMPO-OOH Spin-Adduct as a Model for Study of Decomposition of Organic Hydroperoxides and the Effects of Sulfide/Selenite Derivatives. An EPR Spin-Trapping Approach.

Lipid hydroperoxides play an important role in various pathophysiological processes. Therefore, a simple model for organic hydroperoxides could be helpful to monitor the biologic effects of endogenous and exogenous compounds. The electron paramagnetic resonance (EPR) spin-trapping technique is a useful method to study superoxide (O2•−) and hydroxyl radicals. The aim of our work was to use EPR with the spin trap 5-tert-butoxycarbonyl-5-methyl-1-pyrroline-N-oxide (BMPO), which, by trapping O2•− produces relatively stable •BMPO-OOH spin-adduct, a valuable model for organic hydroperoxides. We used this experimental setup to investigate the effects of selected sulfur/selenium compounds on •BMPO-OOH and to evaluate the antioxidant potential of these compounds. Second, using the simulation of time-dependent individual BMPO adducts in the experimental EPR spectra, the ratio of •BMPO-OH/•BMPO-OOH—which is proportional to the transformation/decomposition of •BMPO-OOH—was evaluated. The order of potency of the studied compounds to alter •BMPO-OOH concentration estimated from the time-dependent •BMPO-OH/•BMPO-OOH ratio was as follows: Na2S4 > Na2S4/SeO32− > H2S/SeO32− > Na2S2 ~Na2S2/SeO32− ~H2S > SeO32− ~SeO42− ~control. In conclusion, the presented approach of the EPR measurement of the time-dependent ratio of •BMPO-OH/•BMPO-OOH could be useful to study the impact of compounds to influence the transformation of •BMPO-OOH.

Electron Spin Resonance Evidence for Electro-generated Hydroxyl Radicals

Electro-generated hydroxyl radicals (•OH) are of fundamental importance to the electrochemical advanced oxidation process (EAOP). Radical-specific electron spin resonance (ESR) evidence is still lacking in association with the direct electron transfer (DET) reaction of spin trap (e.g., 5,5-dimethyl-1-pyrroline-N-oxide; DMPO) and side reactions of the DMPO-OH adduct in the strongly oxidative environment offered by anodic polarization. Herein, we showed ESR identification of electro-generated •OH in EAOP based on the principle of kinetic selection. Excessive addition of a DMPO agent and fast spin trapping allowed suitable kinetic conditions to be set for effective spin trapping of electro-generated •OH and subsequent ESR identification. Otherwise, interferential triplet signals would emerge due to formation of paramagnetic dimer via dehydrogenation, DET oxidation, and dimerization reactions of the DMPO-OH adduct. The results demonstrate that •OH formation during spin-trapping on the titanium suboxide (TiSO) anode could be quantified as 47.84 ± 0.44 μM at current density of 10 mA cm-2. This value revealed a positive dependence on electrolysis time, current density, and anode potential. The effectiveness of ESR measurements was verified by the results obtained with the terephthalic acid probe. The ESR identification not only provides direct evidence for electro-generated •OH from a fundamental point of view, but also suggests a strategy to screen effective anode materials.

Peroxymonosulfate-enhanced photocatalysis by carbonyl-modified g-C3N4 for effective degradation of the tetracycline hydrochloride

In this work, carbonyl-modified g-C3N4 (CO-C3N4) is prepared through one-step calcination of the melamine-oxalic acid aggregates. The visible light-assisted photocatalytic degradation efficiency of the tetracycline hydrochloride (TCH) for CO-C3N4 is significantly enhanced by introducing the peroxymonosulfate (PMS), and the apparent rate constant is greatly increased from 0.01966 min−1 in CO-C3N4/vis system to 0.07688 min−1 in CO-C3N4/PMS/vis system. It is found that carbonyl for CO-C3N4 might offer possible reactive sites for PMS activation and collection sites of photo-generated electrons, greatly accelerating carrier's separation for PMS activation. The favorable conditions, such as the higher catalyst dosage, higher PMS amount and alkaline pH, contribute to TCH degradation. The deleterious effects of co-existing anions on the TCH degradation efficiency are ranked in a decline: H2PO4− > SO42− > HCO3− > NO3− > Cl−, and it may be affected by the type and amounts of anions and active radicals generated. The radical trapping tests and electron spin resonance (ESR) detection display that the O2−, h+, 1O2, OH and SO4− all contribute to TCH degradation. Meanwhile, possible degradation mechanism, intermediates and degradation pathway of TCH are revealed in CO-C3N4/PMS/vis system. This study will offer a new insight for constructing PMS activation with carbonyl modified g-C3N4 photocatalysis system to achieve effective treatment of organic wastewater.

Cu(II) complexes with peptides from FomA protein containing -His-Xaa-Yaa-Zaa-His and -His-His-motifs. ROS generation and DNA degradation

Mono- and dinuclear Cu(II) complexes with Ac-PTVHNEYH-NH2 (L1) and Ac-NHHTLND-NH2 (L2) peptides from FomA protein of Fusobacterium nucleatum were studied by potentiometry, spectroscopic methods (UV–Vis, CD, EPR) and MS technique. The dominant mononuclear complexes for L1 ligand are: CuHL (pH range 5.0–6.0) with 2N {2Nim}, CuH-2L (pH range 8.0–8.5) and CuH-3L species (above pH 9.0) with 4N {Nim, 3N−} coordination modes. The complexes: CuH-1L with 3N {2Nim, N−}, CuH-2L with 3N {Nim, 2N−} and CuH-3L with 4N {Nim, 3N−} binding sites are proposed for the L2 ligand. Probably in the CuH-2L complex for CuL2 system the second His residue in His-His sequence is bound to Cu(II) ion, while the first His residue may stabilize this complex by His-His and/or His-Cu(II) interactions. The dominant dinuclear Cu2L1 complexes in the pH range 6.5–10.5 are: the Cu2H-4L and Cu2H-6L species with 3N{Nim, 2N−}4N{Nim, 3N−} and 4N{Nim, 3N−}4N{Nim, 3N−} binding sites, respectively. In the case of the Cu2L2 complex in the pH range 7.2–10.5, the Cu2H-4L and Cu2H-7L species dominate with 2N{Nim, N−}4N{Nim, 3N−} and (Cu(OH)42−4N{Nim, 3N−}) coordination modes, respectively. The ability to generate reactive oxygen species (ROS) by uncomplexed Cu(II) ions, ligands and their complexes at pH 7.4 in the presence of hydrogen peroxide or ascorbic acid was studied. UV–Vis, luminescence, EPR spin trapping and gel electrophoresis methods were used. Both complexes produce higher level of ROS compared to those of their ligands. ROS produced by Cu(II) complexes are hydroxyl radical and singlet oxygen, which contribute to oxidative DNA cleavage.

Changes in Photosynthetic Electron Transport during Leaf Senescence in Two Barley Varieties Grown in Contrasting Growth Regimes.

Leaf senescence is an important process for plants to remobilize a variety of metabolites and nutrients to sink tissues, such as developing leaves, fruits and seeds. It has been suggested that reactive oxygen species (ROS) play an important role in the initiation of leaf senescence. Flag leaves of two different barley varieties, cv. Lomerit and cv. Carina, showed differences in the loss of photosystems and in the production of ROS at a late stage of senescence after significant loss of chlorophyll (Krieger-Liszkay etal. 2015). Here, we investigated photosynthetic electron transport and ROS production in primary leaves of these two varieties at earlier stages of senescence. Comparisons were made between plants grown outside in natural light and temperatures and plants grown in temperature-controlled growth chambers under low light intensity. Alterations in the content of photoactive P700, ferredoxin and plastocyanin (PC) photosynthetic electron transport were analyzed using in vivo near-infrared absorbance changes and chlorophyll fluorescence, while ROS were measured with spin-trapping electron paramagnetic resonance spectroscopy. Differences in ROS production between the two varieties were only observed in outdoor plants, whereas a loss of PC was common in both barley varieties regardless of growth conditions. We conclude that the loss of PC is the earliest detectable photosynthetic parameter of leaf senescence while differences in the production of individual ROS species occur later and depend on environmental factors.

Detection of Superoxide Radical in Adherent Living Cells by Electron Paramagnetic Resonance (EPR) Spectroscopy Using Cyclic Nitrones.

Spin trapping with cyclic nitrones coupled to electron paramagnetic resonance (EPR) enables the detection and characterization of oxygen-derived free radicals, such as superoxide and hydroxyl radicals, in living cells. Detection is usually performed on cell suspensions introduced in glass capillaries, gas-permeable tubing, or flat cells, even when cells normally require attachment for growth. However, radical production may be influenced by cell adhesion, while enzymatic or mechanical cell harvesting may damage the cells and alter their metabolic rates. Here, we describe the detection on adherent cells attached to microscope coverslip glasses. This method preserves cell integrity, ensures near physiological conditions for naturally adherent cells, and is relatively simple to set up. Up to 12 conditions can be screened in half a day using a single batch of culture cells.

Essential relation of spin states, trap states and photo-induced polarization for efficient charge dissociation in a polymer-nonfullerene based organic photovoltaic system

Organic nonfullerene acceptors (NFA) have received tremendous research interests due to the efficient interfacial charge transfer (CT) when they combine with polymeric donors. It is of critical importance to unravel, to which extent, spin-dependent excited states, energetic disorder and photo-induced polarization are essentially correlated, and eventually contribute for the photovoltaic action. Herein, we explore them in a polymer-NFA ITTC based organic bulk heterojunction (BHJ) solar cell. With assist of magneto-photocurrent measurements at the short-circuit current density (Jsc) condition and steady state impedance spectroscopic measurements, the dominant mechanism for the Jsc generation is governed by the triplet-charge reaction. We postulate that long lived triplets are more likely to interact with trapped charges at excited states, giving rise to Jsc. It turns out that the trap states may not always act as passive role for the energy loss in the organic photovoltaic system. More importantly, both applied bias voltage and light can effectively manipulate the magnitude and sign of the magneto-photocurrent. By quenching the photo-generated build-in field, the bias-dependent magneto-photocurrent evidently proves the efficient dissociation of polaron pairs at CT states. In particular, the photo-excitation wavelength has strong impact on the hyperfine field. Lastly, we demonstrate that the double beam photo-excitation generated dipole-dipole interaction assists for the electron-hole dissociation. Our work may pave the way for understanding the inside spin- and photo-physical phenomena in the NFA based organic photovoltaic system.