Total Fluorescence Research Articles

Arsenic Levels in Soil and Rice and Health Risk Assessment via Rice Consumption in Industrial Areas of East Java, Indonesia

Industrial use of arsenic can potentially cause environmental problems in water, soil, and air. Arsenic is one of heavy metals that is highly toxic and carcinogenic. Arsenic contamination in the environment is harmful to human health because it can enter the body through the food chain. This study determined the concentration of arsenic in soil and rice and its impact on human health risks. Sampling was carried out in several East Java industrial cities or districts, for instance, Gresik, Mojokerto, Sidoarjo, Nganjuk, Ponorogo, and Surabaya. The measurement of arsenic in soil was done using Energy Dispersive X-Ray fluorescence (EDXRF), while the measurement of arsenic in rice was done by Total X-Ray Fluorescence (TXRF). The results showed that arsenic concentration in several areas of East Java has varying levels. The concentration of arsenic in soil was highest in Gresik (13,786 mg/kg). The highest arsenic concentration in rice was found in Mojokerto (0.154 mg/kg). The results of risk assessment in this study showed that the Hazard Quotient (HQ) value was >1 and the Excess Cancer Risk (ECR) was >10-4 in all areas at the age of children <2 years. Health risk assessment of adults showed HQ>1 and ECR>10-4 in several areas of East Java. This indicates that consumption of rice contaminated with arsenic has the potential to pose non-carcinogenic and carcinogenic health risks.

Spatiotemporal Theranostic Nanoprobes Dynamically Monitor Targeted Tumor Therapy

AbstractCurrently, spatiotemporal theranostic nanoprobes are in great demand, owing to their enhanced target therapy and precise dynamic tracing of in vivo drug fate. Herein, this study highlights the successful development of dynamic theranostic nanoprobes, which are facilely established via self‐assembly between glutathione (GSH)‐responsive dasatinib (DAS) dimers and indocyanine green (ICG). The DAS dimers endow the nanoprobes with aggregation‐induced emission (AIE) characteristic, whose emission wavelength successfully redshifts from 420 to 810 nm compared to DAS‐based nanoprobes, the same as that of ICG, thus improving the total fluorescence intensity. Moreover, the nanoprobes exhibit a dynamic fluorescence intensity conversion that first decreases and then increases at the tumor site via intracellular GSH‐triggered AIE quenching and fluorescence re‐enhancement of ICG, therefore achieving precise tumor diagnosis, prognosis evaluation, and spatiotemporal tracing of drug fate compared to other imaging strategies. Furthermore, the nanoprobes show long‐term circulation stability via suitable particle sizes and zeta potentials, improved tumor accumulation via extracellular protonation and active cellular uptake, efficient drug release via response to the intracellular milieu, and enhanced apoptosis via targeting to intracellular kinase, therefore achieving the significant tumor inhibition. Thus, the spatiotemporal theranostic nanoprobes can dynamically monitor the targeted tumor therapy, greatly advancing their application in clinics.

Magnetic properties of Cr-doped VO2 thin films in tetragonal phase of rutile and their synchrotron-based electronic structures

The present study is focused on the investigation at 400 K of the tetragonal-rutile phase of Cr-doped VO2 (CVO) thin films grown by pulsed laser deposition. Synchrotron-based x-ray measurements of both the surface-sensitive total electron yield (TEY) and bulk-sensitive total fluorescence yield (TFY) modes were used to investigate the pristine and Cr-doped VO2 (5%, 10%, 20%, and 30% of atomic weight). The structural analysis and purity of the crystalline phase of the as-deposited films are manifested via grazing incidence x-ray diffraction patterns, which confirm the tetragonal-rutile phase. The purity of the phase is also confirmed by the presence of Eg-mode phonons in the Raman spectra and its deconvolution reflects on the oxygen-mediated electronic/vibrational transitional effect. A clear hysteretic behavior obtained through vibrating sample magnetometry strongly suggests the ferromagnetic interaction in the thin films of CVO. The local-electronic property of the samples is examined using x-ray absorption spectroscopy (XAS) in TEY and TFY modes where the difference in the configured helicity photons resulted in the fine spectra of x-ray magnetic circular dichroism (XMCD). XAS and XMCD measurements performed at V L2,3 and Cr L2,3 edges explicitly demonstrate the ferromagnetism in the thin films of CVO. The strong hybridization between V 3d and Cr 3d states with O 2p states is evident from the spectra of the O K-edge, resulting in the onset of the cation-pair formation V5+–Cr3+, which is ferromagnetic by means of double-exchange interaction. The theoretical calculation of density functional theory made upon Vienna ab initio simulation package suggests that CVO is in a mixed state of a ferromagnetic-insulator and a half-metallic ferromagnet.

Accelerated Hg loss and increased methylmercury covary with soil organic matter mineralization and dissolved organic matter humification under warming conditions in permafrost marsh, Northeast China

Currently, little is available on how mercury (Hg) methylation couples with soil organic matter decomposition in degraded permafrost in high northern latitudes, where the climate is becoming warmer rapidly. Here, we revealed the complex interactions between soil organic matter (SOM) mineralization, dissolved organic matter (DOM) and methylmercury (MeHg) production based on an 87-day anoxic warming incubation experiment. Results supported remarkably promotion effects of warming on MeHg production, by 130%–205% on average. Total mercury (THg) loss under warming treatment depended on marsh types but showed an increasing trend on the whole. Warming yielded higher proportions of MeHg to THg (%MeHg), increased by 123%–569%. As expected, greenhouse gas emission was significantly enhanced by warming. Warming also strengthened fluorescence intensities of fulvic-like and protein-like DOM, with contributions to total fluorescence intensities of 49%–92% and 8%–51%, respectively. DOM and its spectral features explained 60% variation of MeHg, and the explanation increased to 82% in conjunction with greenhouse gas emissions. The structural equation model implied that warming, greenhouse gas emission, and humification of DOM had positive effects on Hg methylation potential, while microbial-derived DOM showed negative effects on MeHg. These results showed that accelerated Hg loss and increased methylation covaried with greenhouse gas emission and DOM formation under warming conditions in permafrost marsh.

Chloroplast photoprotection: face the light or run and hide?

Chloroplast photoprotection: face the light or run and hide?

Fetal Ovarian Reserve: the Dynamic Changes in Ubiquitin C-Terminal Hydrolase L1.

The regulation of protein turnover by the unique deubiquitinating enzyme ubiquitin C-terminal hydrolase L1 (UCHL1) is only seen in oocytes, spermatogonia, and neurons. Our objective was to investigate variation in expression of UCHL1 across fetal maturation of oocytes that result in lifelong ovarian reserve. We performed a retrospective cohort study of 25 fetal autopsy specimens from 21 to 36weeks. This was an IRB-approved protocol with parental permission for use of tissues for research purposes. Tissues were stained for expression of the oocyte-specific protein UCHL1, and expression levels were evaluated using quantitative immunofluorescence across gestational ages after correction for the area and background absorbance. Corrected total cell fluorescence (CTCF) for expression of UCHL1 within human oocytes was compared across fetal gestational ages and oocyte size. Trends were analyzed using a locally weighted scatterplot smoothing algorithm. Local expression of UCHL1 increases in oocytes across ovarian development reaching a plateau at 27weeks with the maintenance of elevated levels through 36weeks gestational age. This maturation trend is also evidenced by the increase in protein expression as oocyte area increases (r = 0.5530, p ≤ 0.001) with the largest rise occurring as oocytes are enveloped into primordial follicles. The increase in expression as oocytes transition from oogonia into oocytes in primordial follicles and beyond may be part of the preparation of both oocytes and the surrounding somatic cells for the long-term maintenance of the ovarian reserve.

Naked Mole-Rat Cortex Maintains Reactive Oxygen Species Homeostasis During In Vitro Hypoxia or Ischemia and Reperfusion.

Neuronal injury during acute hypoxia, ischemia, and following reperfusion are partially attributable to oxidative damage caused by deleterious fluctuations of reactive oxygen species (ROS). In particular, mitochondrial superoxide (O2•-) production is believed to upsurge during lowoxygen conditions and also following reperfusion, before being dismutated to H2O2 and released into the cell. However, disruptions of redox homeostasis may be beneficially attenuated in the brain of hypoxia-tolerant species, such as the naked mole-rat (NMR, Heterocephalus glaber). As such, we hypothesized that ROS homeostasis is better maintained in the brain of NMRs during severe hypoxic/ ischemic insults and following reperfusion. We predicted that NMR brain would not exhibit substantial fluctuations in ROS during hypoxia or reoxygenation, unlike previous reports from hypoxiaintolerant mouse brain. To test this hypothesis, we measured cortical ROS flux using corrected total cell fluorescence measurements from live brain slices loaded with the MitoSOX red superoxide (O2•-) indicator or chloromethyl 2',7'-dichlorodihydrofluorescein diacetate (CM-H2-DCFDA; which fluoresces with whole-cell hydrogen peroxide (H2O2) production) during various low-oxygen treatments, exogenous oxidative stress, and reperfusion. We found that NMR cortex maintained ROS homeostasis during low-oxygen conditions, while mouse cortex exhibited a ~40% increase and a ~30% decrease in mitochondrial O2•- and cellular H2O2 production, respectively. Mitochondrial ROS homeostasis in NMRs was only disrupted following sodium cyanide application, which was similarly observed in mice. Our results suggest that NMRs have evolved strategies to maintain ROS homeostasis during acute bouts of hypoxia and reoxygenation, potentially as an adaptation to life in an intermittently hypoxic environment.

Toward Low‐Power Cryogenic Metal‐Oxide Semiconductor Field‐Effect Transistors

Herein, cryogenic field‐effect transistors (FETs) are discussed. In particular, the saturation of the subthreshold swing due to band tailing is studied. It is shown with simulations and experiments that engineering of the oxide‐channel interfaces and a strong increase of the gate oxide capacitance are effective in improving the switching behavior of the device. The implication of scaling the oxide capacitance on the power consumption of cryogenic devices is investigated, too. Furthermore, an alternative for conventional doping in cryogenic transistors is discussed. Based on synchrotron X‐Ray absorption spectroscopy at total fluorescence (XAS‐TFY) and ultraviolet photoemission spectroscopy (UPS) measurements, it is shown experimentally that in true nanoscale devices, a simple coating yields a shift of the conduction band that is equivalent to a very high dopant concentration. As a result, nanoscale cryogenic steep slope FETs with strongly improved electrical characteristics become feasible.

Structural and functional changes on polyhydroxy alcohol-mediated curing pork myofibrillar protein: Experimental and molecular simulation investigations

This study aimed to investigate the structural and functional changes in polyhydroxy alcohol-mediated curing on pork myofibrillar proteins (MP). The results obtained from total sulfhydryl groups, surface hydrophobicity, fluorescence and Raman spectroscopies, and solubility demonstrated that the polyhydroxy alcohols (especially xylitol) significantly modified the MP tertiary structure, making this structure more hydrophobic and tighter. However, no significant differences were detected in the secondary structure. Furthermore, the thermodynamic analysis revealed that polyhydroxy alcohols could develop an amphiphilic interfacial layer on the MP surface, significantly increasing the denaturation temperature and enthalpy of denaturation (P < 0.05). On the other hand, the molecular docking and dynamics simulations showed that polyhydroxy alcohols interact with actin mainly through hydrogen bonds and van der Waals forces. Therefore, this could help reduce the effect of high-content salt ions on MP denaturation and improve the cured meat quality.

Heavy metal compartmentalisation in salt marsh and seagrass of the urbanised Swartkops estuary, South Africa

Wetland plants are naturally exposed to high metal concentrations, and often have mechanisms to prevent metal toxicity. This study compared metal concentrations in seagrass (Zostera capensis) and salt marsh (Spartina maritima, Salicornia tegetaria) — to determine their niche as metal sinks. Samples were collected in each season over a year at five sites in the estuary and analysed using a Total X-Ray Fluorescence (TXRF) spectrometer. Spartina maritima and S. tegetaria accumulated in their roots, and displayed little translocation to leaves (BCF = 1–14; TF[leaf/root] < 1). Contrastingly, Z. capensis showed high uptake to its leaves (TF[leaf/root] = 1–8; Mn, Zn, Cr, Pb, Ni, Cu). Spartina maritima and S. tegetaria were identified as good phytostabilisers (BCF > 1, TF[leaf/root] < 1). Compartmentalization was unique to each species, and considering their ecosystem service importance, more plant species should be analysed to estimate their ecological value for management purposes.

Characterization of copper binding to different molecular weight fractions of dissolved organic matter in surface water

Dissolved organic matter (DOM) is a kind of substance with complex compositions and wide molecular weight distribution, which can strongly combine with various pollutants. Therefore, the binding characteristics of DOM and heavy metal pollutants can be studied specifically according to the binding characteristics of DOM and pollutants. In this study, DOM in surface water bodies was divided into three levels (MW < 1 kDa, 1 kDa < MW < 5 kDa, MW > 5 kDa) according to different molecular weights (MW). The binding properties were investigated by fluorescence spectrum analysis and complex model. Four components (C1–C4) were identified by PARAFAC. Among them, the contribution rate of protein-like components C1, C2 and C4 to the total fluorescence intensity reached more than 78%, and the log Ka values of low molecular weight components were the highest, which were 3.28, 3.14 and 3.47, respectively, indicating higher binding ability with Cu2+.With the decrease of molecular weight, the log Kb value increases, indicating that the complexation is more stable. The humic component C3 in high molecular weight has stronger binding stability with Cu2+, but the number of binding sites for C3 is 0.36, while that for C2 is 1.51, indicating that its binding sites and binding ability are relatively low. The results showed that the DOM ligand of Cu2+ in surface water showed a certain molecular weight dependence. In addition, different MW DOM lead to different pollution forms. Different properties of DOM ligand combined with Cu2+ were studied in order to control the migration, transformation, bioavailability, morphology and stability of heavy metal pollutants, and to provide theoretical support for the practical application management of surface water pollution control.

Indirect photodegradation of sulfadimidine and sulfapyridine: Influence of CDOM components and main seawater factors

This study investigated the indirect photodegradation of sulfadimidine (SM2) and sulfapyridine (SP) in the presence of chromophoric dissolved organic matter (CDOM), and studied the influences of main marine factors (salinity, pH, NO3− and HCO3−). Reactive intermediate (RI) trapping experiments demonstrated that triplet CDOM (3CDOM*) played a major role in the photodegradation of SM2 with a 58% photolysis contribution, and the contributions to the photolysis of SP were 32%, 34% and 34% for 3CDOM*, hydroxyl radical (HO·) and singlet oxygen (1O2), respectively. Among the four CDOMs, JKHA, with the highest fluorescence efficiency, exhibited the fastest rate of SM2 and SP photolysis. The CDOMs were composed of one autochthonous humus (C1) and two allochthonous humus (C2 and C3). C3, with the strongest fluorescence intensity, had the strongest capacity to generate RIs and accounted for approximately 22%, 11%, 9% and 38% of the total fluorescence intensity of SRHA, SRFA, SRNOM and JKHA, respectively, indicating the predominance of CDOM fluorescent components in the indirect photodegradation of SM2 and SP. These results demonstrated the photolysis mechanism: The photosensitization of CDOM occurred after its fluorescence intensity decreased, and a large number of RIs (3CDOM*, HO· and 1O2, etc.) were generated by energy and electron transfer, then these RIs reacted with SM2 and SP to cause photolysis. The increase in salinity stimulated the photolysis of SM2 and SP consecutively. The photodegradation rate of SM2 first increased and then decreased with increasing pH, whereas the photolysis of SP was remarkably promoted by high pH but remained stable at low pH. NO3− and HCO3− had little effect on the indirect photodegradation of SM2 and SP. This research may contribute to a better understanding of the fate of SM2 and SP in the ocean and provide new insights into the transformation of other sulfonamides (SAs) in marine ecological environments.

Geographical Classification of Saffron (Crocus Sativus L.) Using Total and Synchronous Fluorescence Combined with Chemometric Approaches.

There is an increasing interest in food science for high-quality natural products with a distinct geographical origin, such as saffron. In this work, the excitation-emission matrix (EEM) and synchronous fluorescence were used for the first time to geographically discriminate between Moroccan saffron from Taroudant, Ouarzazate, and Azilal. Moreover, to differentiate between Afghan, Iranian, and Moroccan saffron, a unique fingerprint was assigned to each sample by visualizing the EEM physiognomy. Moreover, principal component analysis (LDA) and linear discriminant analysis (LDA) were successfully applied to classify the synchronous spectra of samples. High fluorescence intensities were registered for Ouarzazate and Taroudant saffron. Yet, the Azilal saffron was distinguished by its low intensities. Furthermore, Moroccan, Afghan, and Iranian saffron were correctly assigned to their origins using PCA and LDA for different offsets (Δλ) (20-250 nm) such that the difference in the fluorescence composition of the three countries' saffron was registered in the following excitation/emission ranges: 250-325 nm/300-480 nm and 360-425 nm/500-550 nm. These regions are characterized by the high polyphenolic content of Moroccan saffron and the important composition of Afghan saffron, including vitamins and terpenoids. However, weak intensities of these compounds were found in Iranian saffron. Furthermore, a substantial explained variance (97-100% for PC1 and PC2) and an important classification rate (70-90%) were achieved. Thus, the non-destructive applied methodology of discrimination was rapid, straightforward, reliable, and accurate.

Synchrotron X-ray absorption spectroscopy and fluorescence spectroscopy studies of collagen type I-talc intercalated nanocomposites

We investigated the properties of collagen type I-talc intercalated nanocomposites using different techniques. Understanding the conformational changes of collagen induced by clay is noticeably lacking, which is pivotal for understanding the structure of collagen-clay hybrid nanocomposites. We aim to investigate the influence of talc clay minerals on the microstructure of collagen type I molecules. Our main goal is to understand the interaction between talc and collagen molecules and to elucidate the microstructure–property relation of intercalated hybrid nanocomposites. The FT-IR spectrum of collagen type I-talc confirmed the presence of collagen amide bands and talc silicate bonds. Also, the differential scanning calorimetry (DSC) result showed that the addition of talc to the matrix could increase the denaturation temperature (Td = 40.8 °C) compared to pure collagen (Td = 19 °C). The fluorescence intensity increased in collagen type I-talc nanocomposites, indicating that the interaction of talc with collagen chains in collagen type I-talc dispersion varies the micro-environment of the tyrosine amino acids in the collagen fibrils and its fluorescence. We also analyzed X-ray absorption spectroscopy (XAS) in total fluorescence yield (TFY) and total energy yield (TEY) modes of pure collagen and collagen type I-talc nanocomposites prepared at different concentrations of talc and at different temperatures (4 °C, 8 °C, and 14 °C). We have found that the synthesis conditions have a considerable effect on the local atomic environments of nitrogen, carbon, and oxygen atoms in collagen type I-talc nanocomposites. These results are of significance for developing new applications of talc and collagen-based biomaterials in different fields, such as cellular and molecular biology, and drug delivery that enhances the optical signals are needed.

The determination and prediction of the apparent reaction rates between excited triplet-state DOM and selected PPCPs

To determine and predict the reaction rate between 3DOM* and PPCPs in various water bodies, this study defines a reaction rate coefficient (α3DOM∗) to describe the reaction between 3DOM* and PPCPs. As the values also included the inhibition effect of DOM's antioxidant moieties, the calculation of α3DOM∗ is inconsistent with that of a bimolecular rate constant via the steady-state kinetic method. The α3DOM∗ values of 12 selected PPCPs were determined in two DOM solutions and ten DOM-containing water samples collected from typical surface water bodies in Beijing. The Pearson coefficients between nine predictors including the absorbance ratio (E2/E3), specific absorption coefficient at 254 nm (SUVA254), fluorescence index (FI), biological index (BIX), humification index (HIX), pH, total organic carbon (TOC), total fluorescence intensity (TFI) and TOC normalized TFI (TFI/TOC) and α3DOM∗ were examined. Correlation patterns for sulfonamides, β-blockers and diclofenac supported the electron transfer pathway, and was distinctly different from those appeared for FQs where quenching effect played a main part. TFI and TFI/TOC were recognized as the most useful surrogates in empirically predicting α3DOM∗. For PPCPs that went through the electron transfer pathway, α3DOM∗ could be well fit to the Rehm-Weller model assuming a proportional relationship between TFI and △Get. For FQs, α3DOM∗ was found to linearly correlated with TFI/TOC. The α3DOM∗ values determined in this study enrich the database of PPCPs photolysis parameters, and the correlation analysis provides reference for forecasting PPCPs fate in the aquatic environment.

Mild nitridation of perovskite manganite: Synthesis, structure and magnetism

The nitrogen lightly doped perovskite manganite La0.5Ba0.5MnO(3-δ)-xNx was synthesized following a mild nitridation strategy by optimizing annealing temperature, annealing time and NH3/Ar flow rate ratio. Neutron powder diffraction (NPD) characterization evidences an N-doping triggered structural phase transition from pseudo-cubic Pm-3m to tetragonal P4/mmm and further confirms a preferable substitution at O1 and O2 sites closing to the Ba-rich layers. N 1s K-edge X-ray absorption near edge spectrum (XANES) with total fluorescence yield (TFY) mode, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy collectively convince the Mn–N bonded state. The O/N atomic ratio is determined to be 2.26/0.22 by XPS analysis closing to the value of 2.25/0.18 from NPD refinement. Magnetic property characterization reveals that both long-range Mn3+-O-Mn4+ ferromagnetic coupling and high Curie temperature (TC) are maintained upon N-doping. Besides, significant spin frozen with robust domain pinning is identified below TC which can be ascribed to the short-range Mn–N–Mn clusters and/or oxygen defects. This work expands the connotation of transition-metal based perovskite oxynitride and may inspire the development of photosensitive semiconductor device with magnetic response.

Abstract 819: Investigating the impacts of membrane potential on nano-electroporation efficacy

Abstract Electroporation has been shown to be an effective method of intracellular drug delivery and tissue ablation, however it faces significant challenges not only in clinical application due to the risks associated with the necessity of high voltage electrodes, but also due to a lack of fundamental research into the electrical characteristics of cancer cells. In order to improve outcomes in the clinic when using irreversible electroporation(IRE), it will be crucial to create a deeper understanding of the mechanisms underlying electroporation, such as the impacts of resting membrane potential on IRE outcomes. Magnetoelectric-nanoparticles (MENPs)have proven their ability to generate electric fields when stimulated by an external magnetic field and thus may be an effective alternative to electrodes for in-vivo electroporation and electro-chemotherapy. The ability of MENPs to electroporate cells is limited by the strength of their magnetoelectric (ME)effect, as such it is important to optimize MENPs fabrication for future applications. Improving this technology will require a deeper understanding of the membrane potential and other electrical properties of cancer cells.We fabricated MENPs consisting of a magnetostrictive CoFe2O4 core coupled with a piezoelectric BaTiO3shell. SKOV-3 and HOMEC cells were seeded in culture plates and given a 50ul dose of particle suspension, and 10ul of propidium iodide(PI). The cell samples were then stimulated by a 10 minute exposure to an alternating magnetic field of 400Oe at 100Hz. Fluorescence-microscope images were taken at 5 minute intervals during, and for 10 minutes following, the magnetic stimulation. These images were processed in MATLAB to quantify total fluorescence, and thus PI uptake, over time for each cell culture-particle combination.MENPs coupled with magnetic field stimulation were able to cause PI uptake in both HOMEC and SKOV-3 cells, indicating electroporation had occurred. By adding PI at time intervals after stimulation, we were able to determine whether electroporation had been reversible or irreversible by showing dye uptake would stop soon after stimulation had ended in the case of reversible EP but not IRE. We found SKOV-3 to have been reversibly electroporated, and HOMEC to have undergone IRE. To understand these results we used Oxonol uptake in a flow cytometry measurement to estimate resting membrane potential (RMP). HOMEC cells were shown to have a RMP approximately 20mV smaller than SKOV-3, which corresponded to the occurrence of IRE in HOMEC compared to reversible electroporation in SKOV-3.These results demonstrate the efficacy of MENPs to electroporate mammalian cells in the presence of a magnetic field. They also indicate a link between RMP and reversibility of electroporation. Further research into the electrical properties of cancer cells will be needed to formulate a complete model of the interactions between the nanoparticles and mammalian cells. Citation Format: Max Shotbolt, Victoria Andre, Skye Conlan, Ping Liang, Sakhrat Khizroev. Investigating the impacts of membrane potential on nano-electroporation efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 819.

Abstract 2527: Investigation of doxorubicin interference in flow cytometry measurements of apoptosis and necrosis

Abstract Background: Doxorubicin (DOX) is frequently used for investigations of breast cancer using flow cytometry with fluorescent stains for apoptosis and necrosis. DOX interference, however, can occur with these fluorescent measurements which is not reported in many published reports. The objectives of this study were to identify such interference and to assess its extent. Methods: MDA-MB-231 and MCF-7 cells were incubated for 24 h with 0.1, 1, and 10 µM DOX. Cells were then stained for apoptosis and necrosis using two commercial assay kits. Fluorescence was measured with FL1 (apoptosis), FL2 (primary for DOX), and FL3 (necrosis) detectors in cells with DOX alone, with DOX plus stains, and in control cells without DOX. Measurements were repeated two to five times using replicates and trials. Statistics were evaluated by t-tests. Results: Overall, DOX fluorescence interference increased with concentration in both cell lines. After DOX incubation, cells stained with caspase 3/7 and SYTOX showed fluorescence in the FL1 detector indicating caspase 3/7 activation in apoptosis. But the DOX component of fluorescence with this detector ranged from 11 to 95%. Dox fluorescence in the FL3 detector for SYTOX measurements indicating necrosis ranged from 26 to 96% of total fluorescence. Cells stained with Annexin V (with the FITC label) and propidium iodide (PI) showed fluorescence in the FL1 detector for Annexin V indicating apoptosis. However, the DOX component of fluorescence ranged from 11 to 25%. DOX fluorescence in the FL3 detector for PI indicating necrosis ranged from 87 to 106%. Conclusions: Without correction for DOX interference, and even at low concentrations, substantial errors can occur for apoptosis and necrosis measurements using flow cytometry with these stains in breast cancer cells. At high DOX concentrations, the interference can erroneously indicate an extensive presence of these cell death processes. Corrections for DOX interference include background subtraction and flow cytometer compensation. Acknowledgments: The authors gratefully acknowledge financial support from the Agnes Varis Trust for Women in Science (REN), the Milton Lev Memorial Faculty Research Fund (CMO) as well as Saint Joseph’s University support for student research. The authors also thank Bin Chen, PhD, and Richard Howley for assistance with flow cytometry. Citation Format: Rachel E. Nicoletto, Richard Wilkes, Clyde M. Ofner. Investigation of doxorubicin interference in flow cytometry measurements of apoptosis and necrosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2527.

Origin and Quantitative Description of the NESSIAS Effect at Si Nanostructures

AbstractThe electronic structure of SiO2‐ versus Si3N4‐coated low nanoscale intrinsic silicon (Si) shifts away from versus toward the vacuum level Evac, originating from the Nanoscale Electronic Structure Shift Induced by Anions at Surfaces (NESSIAS). Using the quantum chemical properties of the elements involved to explain NESSIAS, an analytic parameter Λ is derived to predict the highest occupied energy level of Si nanocrystals (NCs) as verified by various hybrid‐density functional calculations and NC sizes. First experimental data of Si nanowells (NWells) embedded in SiO2 versus Si3N4 were measured by X‐ray absorption spectroscopy in total fluorescence yield mode (XAS‐TFY), complemented by ultraviolet photoelectron spectroscopy (UPS), characterizing their conduction band and valence band edge energies EC and EV, respectively. Scanning the valence band sub‐structure over NWell thickness yields an accurate estimate of EV shifted purely by spatial confinement, and thus the actual EV shift due to NESSIAS. Offsets of ΔEC = 0.56 eV and ΔEV = 0.89 eV were obtained for 1.9 nm thick NWells in SiO2 versus Si3N4, demonstrating an intrinsic Si type II homojunction. This p/n junction generated by NESSIAS eliminates any deteriorating impact of impurity dopants, offering undoped ultrasmall Si electronic devices with much reduced physical gate lengths and CMOS‐compatible materials.

Comparison of two hybrid sentinel node tracers: indocyanine green (ICG)-99mTc-nanocolloid vs. ICG-99mTc-nanoscan from a nuclear medicine and surgical perspective

BackgroundLymph node (LN) metastasis is a relevant predictor for survival in patients with a.o. penile cancer (PeCa), malignant melanoma. The sentinel node (SN) procedure comprises targeted resection of the first tumour-draining SNs. Here, the hybrid tracer indocyanine green (ICG)-99mTc-nanocolloid has been used for several years to combine optical and nuclear detection. Recently, the resource of the nanocolloid precursor stopped production and the precursor was replaced by a different but chemically comparable colloid, nanoscan. Our aim was to study the performance of ICG-99mTc-nanoscan compared to ICG-99mTc-nanocolloid from a nuclear and surgical perspective.MethodsTwenty-four patients with either PeCa or head-and-neck (H&N) melanoma and scheduled for a SN procedure were included. The initial group (n = 11) received ICG-99mTc-nanocolloid until no longer available; the second group (n = 13) received ICG-99mTc-nanoscan. Tracer uptake was assessed on lymphoscintigraphy and single-photon emission (SPECT). Intraoperatively, SNs were identified using gamma tracing and fluorescence imaging. Ex vivo (back-table) measurements were conducted to quantify the fluorescence emissions. Chemical analysis was performed to compare the ICG assembly on both precursors.ResultsThe mean tracer uptake in the SNs was similar for ICG-99mTc-nanocolloid (2.2 ± 4.3%ID) and ICG-99mTc-nanoscan (1.8 ± 2.6%ID; p = 0.68). 3 SNs (interquartile range (IQR) 3–4) were detected on lymphoscintigraphy in PeCa patients receiving ICG-99mTc-nanoscan compared to 2 SNs (IQR 2–3) in PeCa patients receiving ICG-99mTc-nanocolloid (p = 0.045), no differences were observed in H&N patients. Back-table measurements of resected SNs revealed a lower total fluorescence intensity in the ICG-99mTc-nanoscan group (24*109 arbitrary units (A.U) IQR 1.6*109–14*109 in the ICG-99mTc-nanocolloid group versus 4.6*109 A.U. IQR 2.4*109–42*109 in the ICG-99mTc-nanoscan group, p = 0.0054). This was consistent with a larger degree of “stacked” ICG observed in the nanoscan formulation. No tracer-related adverse events were reported.ConclusionsBased on this retrospective analysis, we can conclude that ICG-99mTc-nanoscan has similar capacity for SN identification as ICG-99mTc-nanocolloid and can safely be implemented in SN procedures.