Accurate prediction of hyaluronic acid concentration under temperature perturbations using near-infrared spectroscopy and deep learning.

Accurate prediction of the concentration of a large number of hyaluronic acid (HA) samples under temperature perturbations can facilitate the rapid determination of HA's appropriate applications. Near-infrared (NIR) spectroscopy analysis combined with deep learning presents an effective solution to this challenge, with current research in this area being scarce. Initially, we introduced a novel feature fusion method based on an intersection strategy and used two-dimensional correlation spectroscopy (2DCOS) and Aquaphotomics to interpret the interaction information in HA solutions reflected by the fused features. Subsequently, we created an innovative, multi-strategy improved Walrus Optimization Algorithm (MIWaOA) for parameter optimization of the deep extreme learning machine (DELM). The final constructed MIWaOA-DELM model demonstrated superior performance compared to partial least squares (PLS), extreme learning machine (ELM), DELM, and WaOA-DELM models. The results of this study can provide a reference for the quantitative analysis of biomacromolecules in complex systems.

Cu1-Fe Dual Sites for Superior Neutral Ammonia Electrosynthesis from Nitrate.

The electrochemical nitrate reduction reaction (NO3RR) is able to convert nitrate (NO3-) into reusable ammonia (NH3), offering a green treatment and resource utilization strategy of nitrate wastewater and ammonia synthesis. The conversion of NO3- to NH3 undergoes water dissociation to generate active hydrogen atoms and nitrogen-containing intermediates hydrogenation tandemly. The two relay processes compete for the same active sites, especially under pH-neutral condition, resulting in the suboptimal efficiency and selectivity in the electrosynthesis of NH3 from NO3-. Herein, we constructed a Cu1-Fe dual-site catalyst by anchoring Cu single atoms on amorphous iron oxide shell of nanoscale zero-valent iron (nZVI) for the electrochemical NO3RR, achieving an impressive NO3- removal efficiency of 94.8% and NH3 selectivity of 99.2% under neutral pH and nitrate concentration of 50 mg L-1 NO3--N conditions, greatly surpassing the performance of nZVI counterpart. This superior performance can be attributed to the synergistic effect of enhanced NO3- adsorption on Fe sites and strengthened water activation on single-atom Cu sites, decreasing the energy barrier for the rate-determining step of *NO-to-*NOH. This work develops a novel strategy of fabricating dual-site catalysts to enhance the electrosynthesis of NH3 from NO3-, and presents an environmentally sustainable approach for neutral nitrate wastewater treatment.

Emigration and fiscal gap in population-exporting region.

This paper analyzes how emigration impacts fiscal gap of population-exporting region in the long term. We construct a general equilibrium model of emigration and fiscal gap and make empirical verification using two-step system GMM model. Among the major lessons from this work, five general and striking results are worth highlighting: (1) the economic losses of emigration are the immediate cause of widening the fiscal gap. (2) in the short and long term, emigration can expand the fiscal revenue gap through the superimposed effect of tax rate and tax base. (3) the gap in fiscal expenditure is widened by the outflow of people in the short term. However, local governments would change the strategy to keep the spending gap from widening in the long run. (4) a positive impact of emigration on the fiscal gap. the more severe population emigration, the larger the fiscal gap. (5) when the trend of emigration becomes irreversible, the subsequent efforts of local governments to expand fiscal expenditure for attraction population would not only fail to revive the regional economy, but aggravate the expansion of fiscal gap. The contribution of research is twofold. On the one hand, it fills the theoretical gap between emigration and fiscal gap because previous studies have paid little attention to the fiscal problems of local government of population outflow. On the other hand, the selection of Northeast China that has been subject to long-term out-of-population migration is good evidence to verify this theory, which is tested very well using the 2S-GMM model. The comprehensive discussion on the relationship between emigration and fiscal gap is helpful to guide those continuous population-exporting regions that are facing a huge fiscal gap how to solve the fiscal gap and unsustainability from the perspective of fiscal revenue and expenditure.

Phonon Pseudoangular Momentum in α-MoO3.

In recent studies, it has been discovered that phonons can carry angular momentum, leading to a series of investigations into systems with three-fold rotation symmetry. However, for systems with two-fold screw rotational symmetry, such as α-MoO3, there has been no relevant discussion. In this paper, we investigated the pseudoangular momentum of phonons in crystals with two-fold screw rotational symmetry. Taking α-MoO3 as an example, we explain the selection rules in circularly polarized Raman experiments resulting from pseudoangular momentum conservation, providing important guidance for experiments. This study of pseudoangular momentum in α-MoO3 opens up a new degree of freedom for its potential applications, expanding into new application domains.

E2F transcription factor 5, a new regulator in adipogenesis to mediate the role of Krüppel-like factor 7 in chicken preadipocyte differentiation and proliferation.

E2F transcription factor 5 (E2F5) gene is a transcription factor, plays an important role in the development of a variety of cells. E2F5 is expressed in human and mouse adipocytes, but its specific function in adipogenesis is unclear. Krüppel-like factor 7 (KLF7) facilitates proliferation and inhibits differentiation in chicken preadipocytes. Our previous KLF7 chromatin immunoprecipitation-sequencing analysis revealed a KLF7-binding peak in the 3' flanking region of the E2F5, indicating a regulatory role of KLF7 in this region. In the present study, we investigated E2F5 potential role, the overexpression and knockdown analyses revealed that E2F5 inhibited the differentiation and promoted the proliferation of chicken preadipocytes. Moreover, we identified enhancer activity in the 3' flanking region (nucleotides +22661/+22900) of E2F5 and found that KLF7 overexpression increased E2F5 expression and luciferase activity in this region. Deleting the putative KLF7-binding site eliminated the promoting effect of KLF7 overexpression on E2F5 expression. Further, E2F5 reversed the KLF7-induced decrease in preadipocyte differentiation and increase in preadipocyte proliferation. Taken together, our findings demonstrate that KLF7 inhibits differentiation and promotes proliferation in preadipocytes by enhancing E2F5 transcription.

High-altitude hypoxia exposure inhibits erythrophagocytosis by inducing macrophage ferroptosis in the spleen.

High-altitude polycythemia (HAPC) affects individuals living at high altitudes, characterized by increased red blood cells (RBCs) production in response to hypoxic conditions. The exact mechanisms behind HAPC are not fully understood. We utilized a mouse model exposed to hypobaric hypoxia (HH), replicating the environmental conditions experienced at 6000 m above sea level, coupled with in vitro analysis of primary splenic macrophages under 1% O2 to investigate these mechanisms. Our findings indicate that HH significantly boosts erythropoiesis, leading to erythrocytosis and splenic changes, including initial contraction to splenomegaly over 14 days. A notable decrease in red pulp macrophages (RPMs) in the spleen, essential for RBCs processing, was observed, correlating with increased iron release and signs of ferroptosis. Prolonged exposure to hypoxia further exacerbated these effects, mirrored in human peripheral blood mononuclear cells. Single-cell sequencing showed a marked reduction in macrophage populations, affecting the spleen's ability to clear RBCs and contributing to splenomegaly. Our findings suggest splenic ferroptosis contributes to decreased RPMs, affecting erythrophagocytosis and potentially fostering continuous RBCs production in HAPC. These insights could guide the development of targeted therapies for HAPC, emphasizing the importance of splenic macrophages in disease pathology.

Ginger exosome-like nanoparticle-derived miRNA therapeutics: A strategic inhibitor of intestinal inflammation.

INTRODUCTION: MicroRNAs (miRNAs) involve in destabilising messenger RNA or repressing translation of target molecules. Ginger-derived exosome-like nanoparticles (GELNs) play a crucial role in modulating intestinal inflammation. Moreover, GELNs contain highly heterogeneous miRNA. However, the role of miRNAs derived from GELNs in immunomodulation remains unclear. OBJECTIVES: This study aimed to elucidate the molecular basis of the unique biological effects mediated by miRNA derived from GELNs on macrophages. METHODS: GELNs were isolated using a combination of commercial exosome isolation kits and the differential centrifugation method, and the lipid composition of GELNs was determined using liquid chromatography-mass spectrometry. Subsequently, PKH26 labelled GELNs were taken up by macrophages. Furthermore, the modulation of inflammatory and immune responses by GELNs or osa-miR164d was assessed through the RNA-seq, RT-qPCR, online databases, and dual luciferase reporter assays to explore the underlying mechanisms of osa-miR164d. Biomimetic exosomes loaded with osa-miR164d were prepared using a microfluidic mixing device and systematically characterized. The therapeutic effects of osa-miR164d on relieving colitis were evaluated. RESULTS: We report for the first time that GELNs-derived osa-miR164d is a regulatory factor of reprogramming macrophage polarization, thereby inhibiting the intestinal inflammatory response. Mechanistically, osa-miR164d directly targets the 3'-UTRs of TAB1, which regulates macrophage polarization through the downregulation of NF-κB expression. In addition, We have designed a biomimetic exosome mimicking GELNs to deliver osa-miR164d (osa-miR164d-MGELNs). Notably, the osa-miR164d-MGELNs can efficiently reprogram macrophages to alleviate colitis-related symptoms. CONCLUSION: Our findings enhance the systematic understanding of how GELNs-derived osa-miR164d mediates cross-kingdom communication and provide an original engineering paradigm for mimicking GELNs to transfer miRNA.

Broccoli extracellular vesicles enhance the therapeutic effects and restore the chemosensitivity of 5-fluorouracil on colon cancer.

Broccoli contains an amount of biologically active substances, which bring beneficial effects on human health. Plant extracellular vesicles have been shown to be novel key factors in cancer diagnosis and tumor therapy. To date, the challenge of overcoming chemoresistance to 5-fluorouracil (5-FU) to facilitate the clinical management of colorectal cancer (CRC) has not been successful. Nevertheless, the functions of broccoli extracellular vesicles (BEVs) in the progression of CRC and 5-FU resistance are predominantly unclear. Herein, we showed that BEVs isolated from broccoli juice were effectively taken up by colorectal cancer HT-29 cells. The co-administration of BEVs and 5-FU significantly inhibited the proliferation and migration of colorectal cancer HT-29 cells, effectively blocking cell cycle progression. Furthermore, the co-administration of BEVs and 5-FU induced apoptosis by stimulating ROS production and disrupting mitochondrial function. Importantly, we found that BEVs reversed 5-FU resistance in HT-29 cells by suppressing the abnormal activation of the PI3K/Akt/mTOR signaling pathway. Collectively, our findings represent a novel strategy for utilizing BEVs to improve the efficacy of colorectal cancer treatment and enhance 5-FU chemosensitivity.

Improved therapeutic consistency and efficacy of CD317+ MSCs through stabilizing TSG6 by PTX3.

BACKGROUND: Previously, we have demonstrated that the batch variations of human platelet lysate (conventional MSC expansion medium) induce MSC heterogeneity and therapeutic inconsistency. On the other hand, the MSCs expanded with chemical defined medium have improved therapeutic consistency. METHODS: In the current study, we studied the MSC subpopulation composition and variation in different types and batches of MSC expansion medium with scRNA-seq analysis. RESULTS: MSCs expanded with different batches of media have higher levels of heterogeneity from the perspective of cell subpopulation composition at transcriptome levels and therapeutic inconsistency. The CD317+ subpopulation has enhanced immune suppression activities. And the percentage of CD317+ MSCs within MSCs is tightly correlated with its immune suppression activities, and also contributes to the heterogeneity and therapeutic inconsistency of MSCs. the CD317+ MSCs have increased expression levels of PTX3, which might stabilize the TSG6 protein and improve the therapeutic effects CONCLUSIONS: Thus, purifying CD317+ MSCs is one efficient strategy to reduce MSC heterogeneity and increase the therapeutic consistency of MSCs.

Chemiluminescent Conjugated Polymer Nanoparticles for Deep-Tissue Inflammation Imaging and Photodynamic Therapy of Cancer.

Deep-tissue optical imaging and photodynamic therapy (PDT) remain a big challenge for the diagnosis and treatment of cancer. Chemiluminescence (CL) has emerged as a promising tool for biological imaging and in vivo therapy. The development of covalent-binding chemiluminescence agents with high stability and high chemiluminescence resonance energy transfer (CRET) efficiency is urgent. Herein, we design and synthesize an unprecedented chemiluminescent conjugated polymer PFV-Luminol, which consists of conjugated polyfluorene vinylene (PFV) main chains and isoluminol-modified side chains. Notably, isoluminol groups with chemiluminescent ability are covalently linked to main chains by amide bonds, which dramatically narrow their distance, greatly improving the CRET efficiency. In the presence of pathologically high levels of various reactive oxygen species (ROS), especially singlet oxygen (1O2), PFV-Luminol emits strong fluorescence and produces more ROS. Furthermore, we construct the PFV-L@PEG-NPs and PFV-L@PEG-FA-NPs nanoparticles by self-assembly of PFV-Luminol and amphiphilic copolymer DSPE-PEG/DSPE-PEG-FA. The chemiluminescent PFV-L@PEG-NPs nanoparticles exhibit excellent capabilities for in vivo imaging in different inflammatory animal models with great tissue penetration and resolution. In addition, PFV-L@PEG-FA-NPs nanoparticles show both sensitive in vivo chemiluminescence imaging and efficient chemiluminescence-mediated PDT for antitumors. This study paves the way for the design of chemiluminescent probes and their applications in the diagnosis and therapy of diseases.

Targeting the Epigenetic Reader ENL Inhibits Super-Enhancer-Driven Oncogenic Transcription and Synergizes with BET Inhibition to Suppress Tumor Progression.

Epigenetic alterations at cis-regulatory elements (CRE) fine-tune transcriptional output. Epigenetic readers interact with CREs and can cooperate with other chromatin regulators to drive oncogene transcription. Here, we found that the YEATS domain-containing histone acetylation reader ENL (eleven-nineteen leukemia) acts as a key regulator of super-enhancers (SE), which are highly active distal CREs, across cancer types. ENL occupied the majority of SEs with substantially higher preference over typical enhancers, and the enrichment of ENL at SEs depended on its ability to bind acetylated histones. Rapid depletion of ENL by auxin-inducible degron tagging severely repressed the transcription of SE-controlled oncogenes, such as MYC, by inducing the decommissioning of their SEs, and restoring ENL protein expression largely reversed these effects. Additionally, ENL was indispensable for the rapid activation of SE-regulated immediate early genes in response to growth factor stimulation. Furthermore, ENL interacted with the histone chaperone FACT complex and was required for the deposition of FACT over CREs, which mediates nucleosome reorganization required for transcription initiation and elongation. Proper control of transcription by ENL and ENL-associated FACT was regulated by the histone reader BRD4. ENL was overexpressed in colorectal cancer and functionally contributed to colorectal cancer growth and metastasis. ENL degradation or inhibition synergized with BET inhibitors that target BRD4 in restraining colorectal cancer progression. These findings establish the essential role of epigenetic reader ENL in governing SE-driven oncogenic transcription and uncover the potential of ENL intervention to increase sensitivity to BET inhibition. SIGNIFICANCE: ENL plays a key role in decoding epigenetic marks at highly active oncogenic super-enhancers and can be targeted in combination with BET inhibition as a promising synergistic strategy for optimizing cancer treatment.

Three Stages of Dynamic Assembly Process of Dipeptide-Based Supramolecular Gel Revealed by In Situ Infrared Spectroscopy.

The exploration of short peptide-based assembly is vital for understanding protein-misfolding-associated diseases and seeking strategies to attenuate aggregate formation. While, the molecular mechanism of their structural evolution remains poorly studied in view of the dynamic and unpredictable assembly process. Herein, infrared (IR) spectroscopy, which serves as an in situ and real-time analytical technique, was intelligently employed to investigate the mechanism of phase transition and aggregate formation during the dynamic assembly process of diphenylalanine. Combined with other spectroscopy and electron microscopy technologies, three stages of gel formation and the main driving forces in different stages were revealed. A variety of stoichiometric methods such as continuous wavelet transform, principal component analysis, and two-dimensional correlation spectroscopy techniques were conducted to analyze the original time-dependent IR spectra to obtain detailed information on the changes in the amide bands and hydration layer. The microenvironment of hydrogen bonding among amide bands was significantly changed with the addition of pyridine derivatives, resulting in great differences in the properties of co-assembled gels. This work not only provides a universal analytical way to reveal the dynamic assembly process of dipeptide-based supramolecular gel but also expands their applications in supramolecular regulation and high-throughput screens in situ.

CRMP5 participates in oocyte meiosis by regulating spastin to correct microtubule-kinetochore misconnection.

Our previous studies have suggested that spastin, which aggregates on spindle microtubules in oocytes, may promote the assembly of mouse oocyte spindles by cutting microtubules. This action may be related to CRMP5, as knocking down CRMP5 results in reduced spindle microtubule density and maturation defects in oocytes. In this study, we found that, after knocking down CRMP5 in oocytes, spastin distribution shifted from the spindle to the spindle poles and errors in microtubule-kinetochore attachment appeared in oocyte spindles. However, CRMP5 did not interact with the other two microtubule-severing proteins, katanin-like-1 (KATNAL1) and fidgetin-like-1 (FIGNL1), which aggregate at the spindle poles. We speculate that, in oocytes, due to the reduction of spastin distribution on chromosomes after knocking down CRMP5, microtubule-kinetochore errors cannot be corrected through severing, resulting in meiotic division abnormalities and maturation defects in oocytes. This finding provides new insights into the regulatory mechanisms of spastin in oocytes and important opportunities for the study of meiotic division mechanisms.

Conjugated Polymer Composite Nanoparticles Augmenting Photosynthesis-Based Light-Triggered Hydrogel Promotes Chronic Wound Healing.

Diabetic chronic wounds are characterized by local hypoxia, impaired angiogenesis, and bacterial infection. In situ, self-supply of dissolved oxygen combined with the elimination of bacteria is urgent and challenging for chronic nonhealing wound treatment. Herein, an oxygen-generating system named HA-L-NB/PFE@cp involving biological photosynthetic chloroplasts (cp)/conjugated polymer composite nanoparticles (PFE-1-NPs@cp) and light-triggered hyaluronic acid-based (HA-L-NB) hydrogel for promoting diabetic wound healing is introduced. Briefly, conjugated polymer nanoparticles (PFE-1-NPs) possess unique light harvesting ability, which accelerates the electron transport rates in photosystem II (PS II) by energy transfer, elevating photosynthesis beyond natural chloroplasts. The enhanced release of oxygen can greatly relieve hypoxia, promote cell migration, and favor antibacterial photodynamic therapy. Additionally, the injectable hydrogel precursors are employed as a carrier to deliver PFE-1-NPs@cp into the wound. Under light irradiation, they quickly form a gel by S-nitrosylation coupling reaction and in situ anchor on tissues through amine-aldehyde condensation. Both in vitro and in vivo assays demonstrate that the oxygen-generating system can simultaneously relieve wound hypoxia, eliminate bacteria, and promote cell migration, leading to the acceleration of wound healing. This study provides a facile approach to develop an enhanced oxygen self-sufficient system for promoting hypoxic tissue, especially diabetic wound healing.

Bioactive Conjugated Polymer-Based Biodegradable 3D Bionic Scaffolds for Facilitating Bone Defect Repair.

Bone defect regeneration is one of the great clinical challenges. Suitable bioactive composite scaffolds with high biocompatibility, robust new-bone formation capability and degradability are still required. This work designs and synthesizes an unprecedented bioactive conjugated polymer PT-C3 -NH2 , demonstrating low cytotoxicity, cell proliferation/migration-promoting effect, as well as inducing cell differentiation, namely regulating angiogenesis and osteogenesis to MC3T3-E1 cells. PT-C3 -NH2 is incorporated into polylactic acid-glycolic acid (PLGA) scaffolds, which is decorated with caffeic acid (CA)-modified gelatin (Gel), aiming to improve the surface water-wettability of PLGA and also facilitate to the linkage of conjugated polymer through catechol chemistry. A 3D composite scaffold PLGA@GC-PT is then generated. This scaffold demonstrates excellent bionic structures with pore size of 50-300 µm and feasible biodegradation ability. Moreover, it also exhibites robust osteogenic effect to promote osteoblast proliferation and differentiation in vitro, thus enabling the rapid regeneration of bone defects in vivo. Overall, this study provides a new bioactive factor and feasible fabrication approach of biomimetic scaffold for bone regeneration.

Mood assessments of family caregivers of patients with severe brain injury in China.

OBJECTIVES: Long-term care of severe brain injury patients places a significant mental burden on family caregivers, yet few studies have reported the situation in China. We aimed to describe the mood states of family caregivers of patients with severe brain injury and examine the influencing factors that affect caregivers' moods. METHODS: Cross-sectional survey was used to assess the mood profiles of Chinese family caregivers between February 2019 and February 2020. Demographic data of caregivers and patients, the Patient Health Questionnaire (PHQ-9) and the Generalized Anxiety Disorder scale (GAD-7) were used to assess the level of depressive and anxiety symptoms. The quality of life score was also assessed by a visual analog scale, and the Coma Recovery Scale-Revised was used to assess the patient's consciousness. RESULT: One hundred and one patients with severe brain injury (57 unresponsive wakefulness syndrome, UWS) between the age of 14 and 70 and their main family caregivers were enrolled in the study. Most caregivers displayed depressive (n = 62) and anxiety symptoms (n = 65), with 17 and 20 of these family caregivers reporting (moderately) severe depressive symptom and severe anxiety symptom, respectively. The caregiver's depressive symptom level significantly decreased as the patient's injury lasted longer (r = - 0.208, P = 0.037). Moreover, the age of the patient negatively related to the levels of depressive (r = - 0.310, P = 0.002) and anxiety symptoms (r = - 0.289, P = 0.003) in caregivers. There was a significant positive correlation between anxiety and depressive symptoms scores in family caregivers (r = 0.838, P < 0.001). The higher the level of anxiety (r = - 0.273, P = 0.006) and depressive symptoms (r = - 0.265, P = 0.007), the worse the quality of life. CONCLUSION: Many family caregivers of patients with severe brain injury experience various levels of anxiety and depressive symptoms in China. Tailor-made psychological help seems imperative. Researchers and doctors can provide information about patient's conditions to assist family members in discussing rehabilitation options for patients in different states of consciousness will help to ease anxiety of family caregivers.

The positive effects of positive coping on mental health in college students during the COVID-19 campus lockdown.

Objectives: Isolation has been an effective method to control the spread of COVID-19 over the past 3 years. However, lifestyle changes may have a negative impact on mental health. To examine the effects of positive coping on mental health in college students during the COVID-19 campus lockdown, this study conducted an online cross-sectional survey. Methods: In October 2022, following a prolonged campus lockdown of nearly 3 years, 313 university students from a university in Shandong Province, China, were invited to complete an online questionnaire. The questionnaire comprised a self-administered general situation questionnaire, the Simple Coping Style Scale, and the Hospital Depression and Anxiety Scale. Results: (1) The analysis of variance revealed a significant main effect of coping Style on depression [F(4,300) = 2.446, p = 0.047] during the COVID-19 campus lockdown. A post-hoc test indicated that college students who engaged in study (p = 0.012) or sports (p = 0.027) during their free time had significantly lower depression scores than those who used the Internet. (2) Independent sample t-tests showed significant differences in positive and negative coping styles among college students in terms of depression (t = 6.891, p < 0.001) and anxiety scores (t = 7.745, p < 0.001). (3) Pearson correlation analysis demonstrated a negative correlation between positive coping style and anxiety (r = -0.378, p < 0.001), and between positive coping style and depression (r = 0.427, p < 0.001). Positive correlations were also found between the negative coping style and anxiety (r = 0.155, p = 0.007), and between the negative coping style and depression (r = 0.190, p < 0.001). Discussion: The study suggested that fostering positive coping in students can mitigate mental health issues during crises, providing a blueprint for university mental health initiatives during epidemics.

Tunable Chirality of Self-Assembled Dipeptides Mediated by Bipyridine Derivative.

Supramolecular peptide assemblies have been widely used for the development of biomedical, catalytical, and optical materials with chiral nanostructures in view of the intrinsic chirality of peptides. However, the assembly pathway and chiral transformation behavior of various peptides remain largely elusive especially for the transient assemblies under out-of-equilibrium conditions. Herein, the N-fluorenylmethoxycarbonyl-protected phenylalanine-tyrosine dipeptide (Fmoc-FY) was used as a peptide assembly platform, which showed that the assembly proceeds multistep evolution. The original spheres caused by liquid-liquid phase separation (LLPS) can nucleate and elongate into the formation of right-handed helices which were metastable and easily converted into microribbons. Interestingly, a bipyridine derivative can be introduced to effectively control the assembly pathway and induce the formation of thermodynamically stable right-handed or left-handed helices at different stoichiometric ratios. In addition, the chiral assembly can also be regulated by ultrasound or enzyme catalysis. This minimalistic system not only broadens the nucleation-elongation mechanisms of protein aggregates but also promotes the controllable design and development of chiral biomaterials.

Construction of an OCP-ATR-FTIR Spectroscopy Device to In Situ Monitor the Interfacial Reaction of Contaminants: Competitive Adsorption of Cr(VI) and Oxalate on Hematite.

The comprehensive understanding of contaminant interfacial behavior strongly depends on the in situ characterization technique, which is still a great challenge. In this study, we constructed a device integrated with open-circuit potentialand attenuated total reflectance Fourier transform infrared (OCP-ATR-FTIR) spectroscopy to simultaneously monitor the electrochemical and infrared spectral information on the interfacial reaction for the process analysis, taking the competitive adsorption of hexavalent chromium (Cr(VI)) and oxalate on hematite nanocubes (HNC) as an example. The synchronous OCP and infrared results revealed that Cr(VI) interacted with HNC via bidentate binuclear inner-sphere coordination, accompanied by electron transfer from HNC to Cr(VI), while oxalate was adsorbed on HNC through bidentate mononuclear side-on inner-sphere coordination with electron transfer from HNC to oxalate, and also outer-sphere coordination with negative charge accumulation. When oxalate was added to HNC with preadsorbed Cr(VI), oxalate would occupy the inner-sphere adsorption sites and thus cause the detaching of preadsorbed Cr(VI) from HNC. This study provides a promising in situ characterization technique for real-time interfacial reaction monitoring and also sheds light on the competitive adsorption mechanism of oxalate and Cr(VI) on the mineral surface.