130553 research outputs found
Sort by
Solvent effect on the self-assembly of polyisobutylene-based glycopolymers.
No full textInvestigation of polymeric conformations in different solvents is critical because block copolymer solution morphology is not only associated with the architecture but also with its characteristic features which depend upon the solvent polarity. A series of double hydrophobic diblock copolymers comprising polyisobutylene (PIB) segment and varying sugar pendant units have been prepared by a combination of living cationic and reversible addition-fragmentation chain transfer (RAFT) polymerizations. After the deprotection of the acetate from sugar pendants, the synthesized water-soluble amphiphilic block copolymers showed morphological transformations in both aqueous and organic media. A conformational transition due to a change in solvent polarity from polar protic to nonpolar was supported by 1H NMR spectroscopy. The dynamic light scattering (DLS) experiments demonstrated that the hydrodynamic diameters of aggregates varied with solvent polarity. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) evidenced the morphological changes from micellar to tubular orientation. Finally, the self-assembly behavior of PIB-based glycopolymers due to changes in solvent polarity is proposed
Asymmetric aldol reactions catalyzed by polymeric self-assembly with side-chain dipeptide pendants.
No full textTo explore the role of proline amide moieties in polymer-supported organocatalysts, side-chain l-proline–l-alanine (Pro-Ala) dipeptide-containing block copolymers were synthesized, and their catalytic potential for the aldol reaction was explored. The dipeptide monomer (Boc-Pro-Ala-HEMA) was polymerized to prepare block copolymers in the presence of hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA) and hydrophobic poly(methyl methacrylate) (PMMA) macro-chain transfer agents. Boc group expulsion from the block copolymers produced double hydrophilic PPEGMA-b-P(Pro-Ala-HEMA) (1b) and amphiphilic PMMA-b-P(Pro-Ala-HEMA) (1c) polymers. The solution behaviors of the polymers were studied by various physical techniques, which showed the formation of self-assembled aggregates of 1c in water and N,N-dimethylformamide (DMF)/water solvent mixtures. These polymers are used as organocatalysts during the aldol reaction of cyclohexanone and 4-nitrobenzaldehyde in different solvent polarities, catalyst loadings, temperatures, and reaction times. This work emphasizes superior catalytic activity of 1c at lower catalyst loadings (5%) while maintaining high conversion (95%) and enantioselectivity (94%) across multiple recycling cycles in DMF/water at a 3:1 ratio (v/v)
Unraveling mechanism and enhancing selectivity of a ruii‐bis‐bipyridyl‐morphocumin complex with raft‐generated glycopolymer exploiting warburg effect in cancer.
No full textThe Warburg effect, which generates increased demand of glucose in cancer cells is a relatively underexplored phenomenon in existing commercial drugs to enhance uptake in cancer cells. Here, we present a chemotherapeutic strategy employing a Ru(II)-bis-bipyridyl-morphocumin complex (2) encapsulated in a self-assembling glucose-functionalized copolymer P(G-EMA-co-MMA) (where G=glucose; MMA=methyl methacrylate; EMA=ethyl methacrylate), designed to exploit this effect for enhanced selectivity in cancer treatment. The P(G-EMA-co-MMA) polymer, synthesized via reversible-addition fragmentation chain transfer (RAFT) polymerization, has a number average molecular weight (Mn,NMR) of 8000 g/mol. Complex 2, stable in aqueous media, selectively releases a cytotoxic, lysosome-targeting compound, morphocumin, in the presence of excess hydrogen peroxide (H₂O₂), a reactive oxygen species (ROS) prevalent in tumor microenvironments. Additionally, complex 2 promotes ROS accumulation, which may further enhance morphocumin release through a synergistic domino effect. Comparative studies reveal that 2 outperforms its curcumin Ru(II) complex (1) analog in solution stability, organelle specificity, and cellular mechanisms. Both 1 and 2 exhibit phototherapeutic effects under low-intensity visible light, but their chemotoxicity significantly increases with incubation time in the dark, highlighting the superior chemotherapeutic efficacy of the O,O-coordinating Ru(II) ternary polypyridyl complexes. Complex 2 induces apoptosis via the intrinsic pathway and shows a 9-fold increase in selectivity for pancreatic cancer cells (MIA PaCa-2) over non-cancerous HEK293 cells when encapsulated in the glucose-conjugated polymer (DP@2). Glucose deprivation in the culture medium further enhances drug efficacy by an additional 5-fold. This work underscores the potential of glucose-functionalized polymers and ROS-responsive Ru(II) complexes in targeted cancer therapy
Water-soluble polymeric probe with tryptophan pendants for formaldehyde sensing
No full textFormaldehyde (FA) is a grade-I carcinogen and the most reactive aldehyde in the carbonyl family, posing substantial health hazards. Herein, a water-soluble polymeric probe with side-chain tryptophan pendants is proposed that relies on an FA-induced Pictet-Spengler reaction for FA sensing in an aqueous medium. The polymeric probe shows cyan fluorescence in an aqueous medium after the interaction with FA due to the formation of a β-carboline derivative, confirmed by high-resolution mass spectrum analysis of the product from the model reaction between tryptophan methyl ester and FA. The copolymer’s sensitivity to FA in aqueous solutions at the nanomolar level is estimated using the fluorescence titration method, where ∼20-fold enhancement in fluorescence intensity is observed within 2 min when 200 µM FA is added to the aqueous solution of the copolymer. The probe can selectively detect FA using colorimetric and fluorometric methods with a detection limit as low as 25 nM. The FA-sensing mechanism is studied from the model reaction of tryptophan methyl ester (TME) with FA, and density functional theory (DFT)
ALL-248 Measurable Residual Disease Assessment by Flow Cytometry in T-Cell Acute Lymphoblastic Leukemia
No full textBackground
Minimal/measurable residual disease (MRD) assessed by multicolor flow cytometry (FCM) is a powerful prognostic indicator for risk stratification in acute leukemia, including T-cell acute lymphoblastic leukemia (T-ALL). MRD-positive status in T-ALL is significantly associated with inferior relapse-free survival and overall survival.
Methods
A retrospective study was conducted in 68 newly diagnosed cases of T-ALL from January 2022 to December 2022. Diagnosis of T-ALL was made based on morphology, cytochemistry, and flow cytometric immunophenotyping. Based on the diagnostic phenotype, we subclassified the patients into 3 categories: early thymic precursor T-cell ALL (ETP-ALL), near-ETP-ALL or ETP-like ALL, and non–ETP-ALL.
Results
Patients were immunophenotypically subclassified as ETP-ALL (9, 13.2%), near-ETP-ALL (14, 20.6%), and non–ETP-ALL (45, 66.2%). Median age was12 years (range: 2-62), M:F ratio was 4.2:1. Median hemoglobin was 85 g/L (range: 4.1-14.2 g/L), TLC was 31.48x10/L (range: 0.54-1500x10/L), platelets were 58x10/L (range: 5-665x10/L), LDH was 1079 IU/L (range: 144-12835 IU/L) with peripheral blood and bone marrow blast percentage 76% (0-98%) and 90% (70-98%), respectively. In diagnostic samples, dim to moderate expression of sCD3 was noted only in 4.4%, CD4 in 52.9%, CD8 in 45.6%; 35.3% samples were dual-positive for CD4/CD8, and 33.8% were dual-negative for CD4/CD8 expression. Markers of immaturity like CD1a, CD10, and CD34 were positive in 36.8%, 33.8%, and 44.1%, respectively. One or more myeloid markers were positive in 25.0% of cases. We also noted the expression of B-cell markers like CD19 and cCD79a in a small subset of samples (4.4% and 11.8%, respectively). End-ofinduction (EOI) MRD was available for 73.5% of patients (n=50). MRD was detectable in 28% of patients, with a median MRD level of 0.49% and a range of 0.02–90.0%, including 3 patients who were not in remission and had ≥5% residual blasts in MRD evaluation. In MRD evaluation, dual CD4/CD8 negativity followed by bright expression of CD7 was the common abnormality.
Conclusions
The inclusion of CD4 and CD8, along with other T-cell markers, is highly useful in T-ALL MRD assessment. Baseline immunophenotyping is not required in all cases of T-ALL MRD evaluation. In MRD evaluation, dual CD4/CD8 negativity followed by bright expression of CD7 was the common abnormality
Exploring the structural attributes of yoda1 for the development of new-generation Piezo1 agonist yaddle1 as a vaccine adjuvant targeting optimal T cell activation.
No full textPiezo1, a mechano-activated ion channel, has wide-ranging physiological and therapeutic implications, with the ongoing development of specific agonists unveiling cellular responses to mechanical stimuli. In our study, we systematically analyzed the chemical subunits in Piezo1 protein agonist Yoda1 to comprehend the structure–activity relationship and push forward next-generation agonist development. Preliminary screening assays for Piezo1 agonism were performed using the Piezo1-mCherry-transfected HEK293A cell line, keeping Yoda1 as a positive control. We introduce a novel Piezo1 agonist Yaddle1 (34, 0.40 μM), featuring a trifluoromethyl group, with further exploration through in vitro studies and density functional theory calculations, emphasizing its tetrel interactions, to act as an ambidextrous wedge between the domains of Piezo1. In contrast to the poor solubility of the established agonist Yoda1, our results showed that the kinetic solubility of Yaddle1 (26.72 ± 1.8 μM at pH 7.4) is 10-fold better than that of Yoda1 (1.22 ± 0.11 μM at pH 7.4). Yaddle1 (34) induces Ca2+ influx in human CD4+ T cell, suggesting its potential as a vaccine adjuvant for enhanced T cell activation
Unfolding the significance of regenerative active species in nickel hydroxide-based systems for sustained urea electro-oxidation
No full textElectrochemical urea oxidation (UOR) has gained attention as an alternative to the oxygen evolution reaction (OER) because of its low thermodynamic energy barrier for hydrogen generation. The activity enhancement of the conventional Ni-based catalysts can be addressed by enhancing NiOOH active species, but ensuring stability for a prolonged duration can be a challenging feat. The catalyst degradation is usually attributed to the lack of tolerance for COx released during UOR; however, in this study, we show that the catalyst activity and durability are also governed by the dynamics of the generated NiOOH species in Ni-hydroxides. We have studied the UOR activity and stability of Ni-based hydroxide systems, Ni(OH)2 and Ni3O2(OH)4, having Ni in different oxidation states. Ni3O2(OH)4 shows better UOR activity in 0.1 M KOH as compared to Ni(OH)2, but the activity trend is reversed in 1 M KOH. The time-dependent UOR indicates drastic degradation of activity for Ni3O2(OH)4 in both electrolytes compared to Ni(OH)2. The in situ X-ray absorption study reveals the regeneration of NiOOH active species in Ni(OH)2 during the urea electrooxidation, whereas in Ni3O2(OH)4, the active species gets reduced to Ni(OH)2 rather than getting regenerated. The Ni3O2(OH)4 catalyst seems to undergo fast degradation accompanied by an enhancement in the Ni–O and Ni–Ni coordination number as a function of KOH concentration derived from extended X-ray absorption fine structure analysis. The active species dynamics are further supported through in situ FT-infrared spectral studies. The variation in the contributions of direct and indirect mechanisms to UOR and their correlation with the regeneration of active species are analyzed through an electrochemical impedance study. The present study reveals that the regenerative active species of UOR catalysts have a profound effect on catalyst durability
A perspective on electrochemical point source utilization of CO<sub>2</sub> and other flue gas components to value added chemicals
No full textElectrochemical CO2 reduction reaction (eCO2RR) has been explored extensively for mitigation of noxious CO2 gas generating C1 and C2+ hydrocarbons and oxygenates as value-added fuels and chemicals with remarkable selectivity. The source of CO2 being a pure CO2 feed, it does not fully satisfy the real-time digestion of industrial exhausts. Besides the detrimental effect of noxious gas mixture leading to global warming, there is a huge capital investment in purifying the flue gas mixtures from industries. The presence of other impurity gases affects the eCO2RR mechanism and its activity and selectivity toward C2+ products dwindle drastically. Impurities like NOx, SOx, O2, N2, and halide ions present in flue gas mixture reduce the conversion and selectivity of eCO2RR significantly. Instead of wiping out these impurities via separation processes, new strategies from material chemistry and electrochemistry can open new avenues for turning foes to friends! In this perspective, the co-electroreduction will vividly discussed and supporting role of different heteroatom-containing impurity gases with CO2, generating highly stable C—N, C—S, C—X bonds, and highlight the existing limitations and providing probable solutions for attaining further success in this field and translating this to industrial exhaust streams
Tuning the oxygen electrocatalytic performance of metal-doped graphitic carbon nitride for the development of zinc-air battery
No full textEfficient and durable non-precious cathode catalysts are needed at this hour for the development of fuel cells and metal-air batteries. The instability of one of the well-studied non-precious catalysts, Fe–N–C, in acidic electrolytes and its inferior bifunctional electrocatalytic activity in alkaline electrolytes, shifts the attention towards other electrocatalysts based on Ni and Co. Herein, we demonstrate the synthesis of nitrogen and transition metal (M=Co, Ni) co-doped mesoporous carbon (Co/Ni–N–mC) catalysts for bifunctional oxygen electrocatalysis. The synthetic approach involves the thermal annealing-induced transformation of the graphitic carbon nitride (g–C3N4) to nitrogen-doped graphitic mesoporous carbon (N–mC). The Co–N–mC catalyst has superior bifunctional oxygen electrocatalytic activity. It promotes the 4-electron pathway for the reduction of oxygen to water and is highly durable in alkaline electrolyte. The bifunctional activity is evaluated in terms of the potential gap (ΔE). The small ΔE for Co–N–mC makes it suitable for metal-air batteries. The rechargeable zinc-air battery is fabricated with Co–N–mC and it delivers a specific capacity of 718 mAh g−1Zn and a power density of 122.2 mW/cm2 with long-time charge-discharge cycling stability for 100 h. The synergistic effect between metal nanoparticles and nitrogen-doped carbon matrix, as well as the post-synthetic surface engineering-induced morphological changes, account for the enhanced activity
A Narrative Review on 3-Dimensional Visualization Techniques in Neurosurgical Education, Simulation, and Planning
No full textHigh-fidelity visualization of anatomical organs is crucial for neurosurgical education, simulation, and planning. This becomes much more important for minimally invasive neurosurgical procedures. Realistic anatomical visualization can allow resident surgeons to learn visual cues and orient themselves with the complex 3-dimensional (3D) anatomy. Achieving full fidelity in 3D medical visualization is an active area of research; however, the prior reviews focus on the application area and lack the underlying technical principles. Accordingly, the present study attempts to bridge this gap by providing a narrative review of the techniques used for 3D visualization.
Methods
We conducted a literature review on 3D medical visualization technology from 2018 to 2023 using the PubMed and Google Scholar search engines. The cross-referenced manuscripts were extensively studied to find literature that discusses technology relevant to 3D medical visualization. We also compiled and ran software applications that were accessible to us in order to better understand them.
Results
We present the underlying fundamental technology used in 3D medical visualization in the context of neurosurgical education, simulation, and planning. Further, we discuss and categorize a few important applications based on the 3D visualization techniques they use.
Conclusions
The visualization of virtual human organs has not yet achieved a level of realism close to reality. This gap is largely due to the interdisciplinary nature of this research, population diversity, and validation complexities. With the advancements in computational resources and automation of 3D visualization pipelines, next-gen applications may offer enhanced medical 3D visualization fidelity