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1.
Front Genet ; 15: 1377434, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38756450

RESUMO

Background: Gastric cancer (GC) continues to be one of the leading causes of cancer-related deaths globally. Diet significantly influences the incidence and progression of GC. However, the relationship between dietary intake and GC is inconsistent. Methods: A study was conducted with adults who participated in the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2016 to investigate possible associations between 32 dietary factors and GC. To further detect potential causal relationships between these dietary factors and the risk of GC, a two-sample Mendelian randomization (MR) analysis was conducted. The primary method employed was the inverse variance weighted (IVW) analysis, and its results were further validated by four other methods. Results: Of the 35,098 participants surveyed, 20 had a history of GC. Based on the results of weighted logistic multivariate analysis, it was observed that there was a positive correlation between total fat intake [odds ratio (OR) = 1.09, 95% confidence interval (CI): (1.01-1.17), p = 0.03] and GC as well as negative association of dietary monounsaturated fatty acids (MUFAs) intake [OR = 0.83, 95% CI: (0.76-0.92), p < 0.001]. Further evaluations of the odds of GC across the quartiles of dietary MUFAs showed that the top quartile of total MUFA intake was associated with a lower likelihood of GC in three different models [model1: OR = 0.03, 95% CI: (0.00-0.25), p < 0.01; model2: OR = 0.04, 95% CI: (0.00-0.38), p = 0.01; model3: OR = 0.04, 95% CI: (0.00-0.40), p = 0.01]. For the MR analyses, genetic instruments were selected from the IEU Open GWAS project; IVW analysis showed that GC risk was not associated with MUFAs [OR = 0.82, 95% CI: (0.59-1.14), p = 0.23] or the ratio of MUFAs to total fatty acids [OR = 1.00, 95% CI: (0.75-1.35), p = 0.98]. Similar results were observed when using the other MR methods. Conclusion: The NHANES study revealed that consuming MUFAs was linked to a lower risk of GC, although the results of MR analyses do not provide evidence of a causal relationship. Additional research is therefore necessary to clarify these findings.

2.
ACS Nano ; 18(19): 12468-12476, 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38699893

RESUMO

Na super ionic conductor (NASICON)-type polyanionic vanadium fluorophosphate Na3V2O2(PO4)2F (NVOPF) is a promising cathode material for high-energy sodium-ion batteries. The dynamic diffusion and exchange of sodium ions in the lattice of NVOPF are crucial for its electrochemical performance. However, standard characterizations are mostly focused on the as-synthesized material without cycling, which is different from the actual battery operation conditions. In this work, we investigated the hopping processes of sodium in NVOPF at the intermediate charging state with 23Na solid-state nuclear magnetic resonance (ssNMR) and density functional theory (DFT) calculations. Our experimental characterizations revealed six distinct sodium coordination sites in the intermediate structure and determined the exchange rates among these sites at variable temperatures. The theoretical calculations showed that these dynamic processes correspond to different ion transport pathways in the crystalline lattice. Our combined experimental and theoretical study uncovered the underlying mechanisms of the ion transport in cycled NVOPF and these understandings may help the optimization of cathode materials for sodium-ion batteries.

3.
Cancer Lett ; 592: 216926, 2024 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-38714291

RESUMO

Gastric cancer (GC) is one of the most common cancer worldwide. Neural invasion (NI) is considered as the symbiotic interaction between nerves and cancers, which strongly affects the prognosis of GC patients. Small extracellular vesicles (sEVs) play a key role in intercellular communication. However, whether sEVs mediate GC-NI remains unexplored. In this study, sEVs release inhibitor reduces the NI potential of GC cells. Muscarinic receptor M3 on GC-derived sEVs regulates their absorption by neuronal cells. The enrichment of sEV-circVAPA in NI-positive patients' serum is validated by serum high throughput sEV-circRNA sequencing and clinical samples. sEV-circVAPA promotes GC-NI in vitro and in vivo. Mechanistically, sEV-circVAPA decreases SLIT2 transcription by miR-548p/TGIF2 and inhibits SLIT2 translation via binding to eIF4G1, thereby downregulates SLIT2 expression in neuronal cells and finally induces GC-NI. Together, this work identifies the preferential absorption mechanism of GC-derived sEVs by neuronal cells and demonstrates a previously undefined role of GC-derived sEV-circRNA in GC-NI, which provides new insight into sEV-circRNA based diagnostic and therapeutic strategies for NI-positive GC patients.

4.
J Chem Theory Comput ; 20(6): 2349-2361, 2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-38490993

RESUMO

Proper construction of the density matrix based on surface hopping trajectories remains a difficult problem. Due to the well-known overcoherence in traditional surface hopping simulations, the electronic wave function cannot be used directly. In this work, we propose a consistent density matrix construction method, which takes the advantage of occupation of active states to rescale the coherence calculated by wave functions and ensures the intrinsic consistency of the density matrix. This new trajectory analysis method can be used for both Tully's fewest switches surface hopping (FSSH) and our recently proposed branching corrected surface hopping (BCSH). As benchmarked in both one- and two-dimensional standard scattering models, the new approach combined with BCSH trajectories achieves highly accurate time-dependent spatial distributions of adiabatic populations and coherence compared to exact quantum results.

5.
J Phys Chem Lett ; 15(12): 3345-3353, 2024 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-38498301

RESUMO

It is well-known that the widely utilized fewest switches surface hopping method suffers from the severe overcoherence problem, and thus adiabatic populations calculated by wave functions are generally inferior to those based on active states. More importantly, to achieve a complete description of nonadiabatic dynamics, the density matrix is essential. In this paper, we present an auxiliary branching corrected surface hopping (A-BCSH) method that introduces auxiliary wave packets (WPs) on the adiabatic potential energy surfaces for trajectory branching. Both rapid and gradual separation of WP components on different surfaces are characterized, and thus the correct decoherence time along each trajectory is captured. As demonstrated in the three standard Tully models, A-BCSH exhibits excellent internal consistency. Namely, close adiabatic populations are obtained based on both wave functions and active states. In particular, A-BCSH successfully obtains a reliable time-dependent spatial distribution of the density matrix, which relies only on electronic wave functions. Due to its high performance, our A-BCSH method provides a new and highly promising perspective on further development of more consistent surface hopping with reliable wave function.

6.
J Phys Chem Lett ; 15(4): 1006-1018, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38298156

RESUMO

Metal halide perovskites exhibit remarkable properties for optoelectronic applications, yet their susceptibility to ion migration poses challenges for device stability. Previous research has predominantly focused on the migration of the halide ions. However, the migration of cations, which also has a significant influence on the device performance, is largely overlooked. In this Perspective, we review the migration of cations and their impacts on perovskite materials and devices. Special attention shall be devoted to recent insights into the migration of L-site organic cations in 2D/3D perovskites. We outline inspirations and directions for further research into the cation migration of perovskites, highlighting new possibilities in advancing perovskite optoelectronics.

7.
Heliyon ; 10(1): e23349, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38173527

RESUMO

Copper-doped Zinc Tellurium (ZnTe:Cu) films were deposited on borosilicate glass using magnetron co-sputtering technique. The influence of the substrate temperature on the structural, morphological, optical and electrical properties of ZnTe:Cu films was investigated by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), UV-Vis spectrophotometer and Hall effect measurement system. The results indicate that substrate temperature significantly affects the properties of the ZnTe:Cu films. When the substrate temperature increases from room temperature to 600 °C, the (111)-preferred orientation of ZnTe:Cu films is gradually replaced by the (220)-preferred orientation. At high substrate temperatures (≥500 °C), the CuxTe phase appears in the ZnTe:Cu films, resulting in higher carrier concentration (>1019 cm-3) and lower resistivity (<10-2 Ω cm) of the prepared films.

8.
Nat Commun ; 15(1): 288, 2024 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-38177094

RESUMO

The charge-transport properties of conjugated polymers have been studied extensively for opto-electronic device applications. Some polymer semiconductors not only support the ambipolar transport of electrons and holes, but do so with comparable carrier mobilities. This opens the possibility of gaining deeper insight into the charge-transport physics of these complex materials via comparison between electron and hole dynamics while keeping other factors, such as polymer microstructure, equal. Here, we use field-induced electron spin resonance spectroscopy to compare the spin relaxation behavior of electron and hole polarons in three ambipolar conjugated polymers. Our experiments show unique relaxation regimes as a function of temperature for electrons and holes, whereby at lower temperatures electrons relax slower than holes, but at higher temperatures, in the so-called spin-shuttling regime, the trend is reversed. On the basis of theoretical simulations, we attribute this to differences in the delocalization of electron and hole wavefunctions and show that spin relaxation in the spin shuttling regimes provides a sensitive probe of the intimate coupling between charge and structural dynamics.

9.
J Biosci Bioeng ; 137(3): 165-172, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38212152

RESUMO

6,7-Bis-(2-methoxyethoxy)-4(3H)-quinazolinone (BMEQ) was selected from quinazolinones for its strong tyrosinase inhibitory activity (IC50 = 160 ± 6 µM). It suppressed tyrosinase activity in a competitive way and quenched the fluorescence of the enzyme through a static mechanism. The binding of BMEQ to tyrosinase increased the hydrophobicity of the latter and facilitated non-radiative energy transfer between them. The formation of BMEQ-tyrosinase complex was driven by hydrogen bonds and hydrophobic interactions, and it loosened the basic framework structure of tyrosinase, affecting the conformation of the enzyme, and leading to a decrease in tyrosinase activity. In addition, the BMEQ postponed the oxidation of phenolics and flavonoids by inhibiting polyphenol oxidase (PPO) and peroxidase (POD), which resulted in the inhibition of the browning of fresh-cut apples. This study identified a novel tyrosinase inhibitor BMEQ and verified its potential application for improving the preservation of postharvest fruits.


Assuntos
Malus , Monofenol Mono-Oxigenase , Quinazolinonas/farmacologia , Frutas
10.
Angew Chem Int Ed Engl ; 63(15): e202400467, 2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38273162

RESUMO

How Nature synthesizes enantiomerically pure substances from achiral or racemic resources remains a mystery. In this study, we aimed to emulate this natural phenomenon by constructing chiral tetrahedral cages through self-assembly, achieved by condensing two achiral compounds-a trisamine and a trisaldehyde. The occurrence of intercomponent CH⋅⋅⋅π interactions among the phenyl building blocks within the cage frameworks results in twisted conformations, imparting planar chirality to the tetrahedrons. In instances where the trisaldehyde precursor features electron-withdrawing ester side chains, we observed that the intermolecular CH⋅⋅⋅π forces are strong enough to prevent racemization. To attain enantioselective self-assembly, a chiral amine was introduced during the imine formation process. The addition of three equivalents of chiral amino mediator to one equivalent of the achiral trisaldehyde precursor formed a trisimino intermediate. This chiral compound was subsequently combined with the achiral trisamino precursor, leading to an imine exchange reaction that releasing the chiral amino mediator and formation of the tetrahedral cage with an enantiomeric excess (ee) of up to 75 %, exclusively composed of achiral building blocks. This experimental observation aligns with theoretical calculations based on the free energies of related cage structures. Moreover, since the chiral amine was not consumed during the imine exchange cycle, it enabled the enantioselective self-assembly of the tetrahedral cage for multiple cycles when new batches of the achiral trisaldehyde and trisamino precursors were successively added.

11.
Int Wound J ; 21(1): e14392, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37722871

RESUMO

The meta-analysis aimed to assess and compare the effect of closed-incision negative pressure wound (NPW) treatment in vascular surgery. Using dichotomous or contentious random or fixed effect models, the outcomes of this meta-analysis were examined, and the odds Ratio (OR) and the mean difference (MD) with 95% confidence intervals (CIs) were computed. Ten examinations from 2017 to 2022 were enrolled for the present meta-analysis, including 2082 personals with vascular surgery. Closed-incision NPW treatment had significantly lower infection rates (OR, 0.39; 95% CI, 0.30-0.51, p < 0.001), grade I infection rates (OR, 0.33; 95% CI, 0.20-0.52, p < 0.001), grade II infection rates (OR, 0.39; 95% CI, 0.21-0.71, p = 0.002), and grade III infection rates (OR, 0.31; 95% CI, 0.13-0.73, p = 0.007), and surgical re-intervention (OR, 0.49; 95% CI, 0.25-0.97, p = 0.04) compared to control in personal with vascular surgery. However, no significant differences were found between closed-incision NPW treatment and control in the 30-day mortality (OR, 0.54; 95% CI, 0.29-1.00, p = 0.05), antibiotic treatment (OR, 0.53; 95% CI, 0.24-1.19, p = 0.12), and length of hospital stay (MD, -0.02; 95% CI, -0.24-0.19, p = 0.83) in personnel with vascular surgery. The examined data revealed that closed-incision NPW treatment had significantly lower infection rates, grade I infection rates, grade II infection rates, and grade III infection rates, surgical re-intervention, however, there were no significant differences in 30-day mortality, antibiotic treatment, or length of hospital stay compared to control group with vascular surgery. Yet, attention should be paid to its values since some comparisons had a low number of selected studies.


Assuntos
Tratamento de Ferimentos com Pressão Negativa , Ferida Cirúrgica , Humanos , Infecção da Ferida Cirúrgica/epidemiologia , Infecção da Ferida Cirúrgica/terapia , Ferida Cirúrgica/terapia , Procedimentos Cirúrgicos Vasculares , Antibacterianos
12.
Cancer Lett ; 581: 216510, 2024 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-38029830

RESUMO

Tripartite motif-containing protein 29 (TRIM29) is a member of TRIM family protein which has been reported to play a role in the progress of inflammatory and cancer diseases. However, its specific role in gastric cancer (GC) has yet to be fully understood. Here, we investigated the expression of TRIM29 in gastric cancer and its functions in the antitumor immunity. TRIM29 expression was lower in tumor tissues than that in paired normal tissues. Lower expression of TRIM29 was related to aberrant hypermethylation of CpG islands in TRIM29 gene. Comprehensive proteomics and immunoprecipitation analyses identified IGF2BP1 as TRIM29 interactors. TRIM29 interacted with IGF2BP1 and induced its ubiquitination at Lys440 and Lys450 site by K48-mediated linkage for protein degradation. IGF2BP1 promoted PD-L1 mRNA stability and expression in a 3'UTR and m6A-dependent manner. Functionally, TRIM29 enhanced antitumor T-cell immunity in gastric cancer dependent on the IGF2BP1/PD-L1 axis in vivo and in vitro. Clinical correlation analysis revealed that TRIM29 expression in patient samples was associated with CD8+ immune cell infiltration in the GC microenvironment and the overall survival rates of GC patients. Our findings revealed a crucial role of TRIM29 in regulating the antitumor T-cell immunity in GC. We also suggested that the TRIM29/IGF2BP1/PD-L1 axis could be used as a diagnostic and prognostic marker of gastric cancer and a promising target for GC immunotherapy.


Assuntos
Antígeno B7-H1 , Neoplasias Gástricas , Humanos , Antígeno B7-H1/genética , Antígeno B7-H1/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Regulação para Baixo , Neoplasias Gástricas/patologia , Linfócitos T/metabolismo , Fatores de Transcrição/genética , Microambiente Tumoral
13.
J Phys Chem Lett ; 14(44): 9855-9863, 2023 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-37890155

RESUMO

When the traditional Ehrenfest mean field approach is employed to simulate nonadiabatic dynamics, an effective wave packet (WP) on the average potential energy surface (PES) is utilized to describe the nuclear motion. In the fully quantum picture, however, the WP components on different adiabatic PESs gradually separate in space because they evolve under different velocities and forces. Due to trajectory branching of the WP components, proper decoherence needs to be taken into account, and the spatial distribution of population cannot be described by a single effective WP. Here, we propose an auxiliary branching corrected mean field (A-BCMF) method, where trajectories of auxiliary WPs on adiabatic PESs are introduced. As benchmarked in the three standard Tully models, A-BCMF not only gives correct channel populations but also captures an accurate time-dependent spatial distribution of population. Thereby, we reveal the important role of auxiliary WPs in solving intrinsic problems of the widely used mean field description of nonadiabatic dynamics.

14.
Adv Mater ; 35(49): e2306135, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37776317

RESUMO

Layered inorganic material, with large-area interlayer surface and interface, provides an essential material platform for constructing new configuration of functional materials. Herein, a layered material pillared with nanoclusters realizing high temperature thermal insulation performance is demonstrated for the first time. Specifically, systematic synchrotron radiation spectroscopy and finite element calculation analysis show that ZrOx nanoclusters served as "pillars" to effectively produce porous structures with enough boundary defect while maintaining the layered structure, thereby significantly reducing solid state thermal conductivity (≈0.32 W m-1  K-1 , 298-573 K). Moreover, the layered inorganic silicate material assembled aerogel also exhibits superior thermal insulation performance from room temperature (0.034 W m-1  K-1 , 298 K, air conditions) to high temperature (0.187 W m-1  K-1 , 1073 K, air conditions) and largely enhanced compressive strength (42 kPa at 80% compression), which is the best layered material-based aerogel that has achieved synergistic improvement in thermal and mechanical performance so far. Layered inorganic silicate aerogel pillared by nanoclusters will pave a new avenue for the design of advanced thermal insulation materials under extreme conditions.

15.
J Invest Surg ; 36(1): 2257785, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37731247

RESUMO

BACKGROUND: The prognostic significance of neural invasion (NI) in gastric cancer (GC) has not been established. This study is to investigate the characteristic and prognostic value of NI in GC. METHODS: 592 patients who had undergone gastrectomy for GC were retrospectively analyzed. NI was defined when cancer cells infiltrated into the perineurium or neural fascicles by hematoxylin and eosin staining of surgical specimens. NI and the other clinical factors were analyzed. RESULTS: NI was detected in 270 of the 592 patients. NI was associated with tumor size, site, depth of invasion, lymph node metastasis, TNM stage, D dissection, tumor differentiation, Lauren classification, and blood vessel invasion. NI was associated with the overall survival. Multivariate analysis indicated that NI was not an independent prognostic factor for total patients, while NI independently predicted prognosis for age < 60 and lymph node metastasis negative patients by subgroup analysis. Concomitant existence of NI with tumor size ≥3cm, TNM stage III, or diffused Lauren classification independently predicted prognosis. CONCLUSIONS: The frequency of NI is high in GC patients and increases with disease progression. NI is related to poor survival in GC patients who underwent curative gastrectomy and provides independent prognostic value for young and lymph node metastasis negative patients.


Assuntos
Neoplasias Gástricas , Humanos , Neoplasias Gástricas/cirurgia , Metástase Linfática , Prognóstico , Estudos Retrospectivos , Gastrectomia , Linfonodos
16.
J Phys Chem Lett ; 14(34): 7680-7689, 2023 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-37606199

RESUMO

Surface hopping simulations have achieved great success in many different fields, but their reliability has long been limited by the overcoherence problem. We here present a general machine learning assisted approach to identify optimal decoherence time formulas for surface hopping using exact quantum dynamics as references. In order to avoid computationally expensive force calculations, we use the nuclear kinetic energy and the adiabatic energy difference to iteratively generate the descriptor space. Through multilayer screening of the candidate descriptors and discrete optimization of the relevant parameters, we obtain new energy-based decoherence time formulas. As benchmarked in thousands of diverse multilevel systems and six standard scattering models, surface hopping with our new decoherence time formulas nearly reproduces the exact quantum dynamics while maintaining high efficiency. Thereby, our approach provides a promising avenue for systematically improving the accuracy of surface hopping simulations in complex systems from quantum dynamics data.

17.
Front Pharmacol ; 14: 1202676, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37637421

RESUMO

Pulmonary hypertension (PH) is a pathophysiological condition of increased pulmonary circulation vascular resistance due to various reasons, which mainly leads to right heart dysfunction and even death, especially in critically ill patients. Although drug interventions have shown some efficacy in improving the hemodynamics of PH patients, the mortality rate remains high. Hence, the identification of new targets and treatment strategies for PH is imperative. Heparanase (HPA) is an enzyme that specifically cleaves the heparan sulfate (HS) side chains in the extracellular matrix, playing critical roles in inflammation and tumorigenesis. Recent studies have indicated a close association between HPA and PH, suggesting HPA as a potential therapeutic target. This review examines the involvement of HPA in PH pathogenesis, including its effects on endothelial cells, inflammation, and coagulation. Furthermore, HPA may serve as a biomarker for diagnosing PH, and the development of HPA inhibitors holds promise as a targeted therapy for PH treatment.

18.
Nat Commun ; 14(1): 4627, 2023 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-37532710

RESUMO

It is considered a more formidable task to precisely control the self-assembled products containing purely covalent components, due to a lack of intrinsic templates such as transition metals to suppress entropy loss during self-assembly. Here, we attempt to tackle this challenge by using directing groups. That is, the self-assembly products of condensing a 1:2 mixture of a tetraformyl and a biamine can be precisely controlled by slightly changing the substituent groups in the aldehyde precursor. This is because different directing groups provide hydrogen bonds with different modes to the adjacent imine units, so that the building blocks are endowed with totally different conformations. Each conformation favors the formation of a specific product that is thus produced selectively, including chiral and achiral cages. These results of using a specific directing group to favor a target product pave the way for accomplishing atom economy in synthesizing purely covalent molecules without relying on toxic transition metal templates.

19.
Int J Surg Case Rep ; 110: 108598, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37591193

RESUMO

INTRODUCTION AND IMPORTANCE: Neurofibromatosis Type 1 (NF1) is a rare autosomal dominant genetic disorder that affects multiple organs and systems, including the nervous system, integumentary system, and connective tissues. Spontaneous hemothorax occurs infrequently in patients with NF1 and is associated with high fatality rates. However, it is commonly overlooked or misdiagnosed. CASE PRESENTATION: We present the case of a 29-year-old woman with NF1 who complained of chest pain and was detected with hemothorax on radiographic examination. No bleeding sites were identified following thrombectomy. The patient's condition deteriorated with conservative treatment over nine days, posing a potentially life-threatening risk. After a diagnostic evaluation using computerized tomography angiography (CTA) and digital subtraction angiography (DSA) of the neck vasculature, the patient was diagnosed with spontaneous rupture of the vertebral artery (VA) and subclavian artery (SuA) aneurysm. Following a multidisciplinary discussion and extensive investigations, the patient underwent successful endovascular treatment. A VIABAHN covered stent was implanted in the left SuA to overlay the emergent orifice. The endovascular treatment challenge due to the inaccessible of the proximal of left VA. To prevent retrograde flow into the VA aneurysm, the coils were used to embolize the left VA via the right vertebral artery-basilar artery (VA-BA) passage. The patient was alive at the 5-year follow-up without further complications. CLINICAL DISCUSSION: The CTA examination led to the diagnosis of vascular rupture due to NF1, and endovascular treatment was performed to occlude the vascular lumen. There have been no recurrences during the five-year follow-up period. CONCLUSION: Vasculopathy is the second leading cause of death in patients with NF1 after malignancy. Early diagnosis of spontaneous hemothorax in patients with NF1 is crucial, as misdiagnosis can result in missed treatment opportunities. CTA plays a vital role in preliminarily diagnosing the cause of spontaneous hemothorax, while endovascular treatment offers a new therapeutic option for such patients.

20.
Acc Chem Res ; 56(14): 1966-1977, 2023 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-37413974

RESUMO

ConspectusProperties of colloidal semiconductor nanocrystals with a single-crystalline structure are largely dominated by their surface structure at an atomic-molecular level, which is not well understood and controlled, due to a lack of experimental tools. However, if viewing the nanocrystal surface as three relatively independent spatial zones (i.e., crystal facets, inorganic-ligands interface, and ligands monolayer), we may approach an atomic-molecular level by coupling advanced experimental techniques and theoretical calculations.Semiconductor nanocrystals of interest are mainly based on compound semiconductors and mostly in two (or related) crystal structures, namely zinc-blende and wurtzite, which results in a small group of common low-index crystal facets. These low-index facets, from a surface-chemistry perspective, can be further classified into polar and nonpolar ones. Albeit far from being successful, the controlled formation of either polar or nonpolar facets is available for cadmium chalcogenide nanocrystals. Such facet-controlled systems offer a reliable basis for studying the inorganic-ligands interface. For convenience, here facet-controlled nanocrystals refer to a special class of shape-controlled ones, in which shape control is at an atomic level, instead of those with poorly defined facets (e.g., typical spheroids, nanorods, etc).Experimental and theoretical results reveal that type and bonding mode of surface ligands on nanocrystals is facet-specific and often beyond Green's classification (X-type, Z-type, and L-type). For instance, alkylamines bond strongly to the anion-terminated (0001) wurtzite facet in the form of ammonium ions, with three hydrogens of an ammonium ion bonding to three adjacent surface anion sites. With theoretically assessable experimental data, facet-ligands pairing can be identified using density functional theory (DFT) calculations. To make the pairing meaningful, possible forms of all potential ligands in the system need to be examined systematically, revealing the advantage of simple solution systems.Unlike the other two spatial zones, the ligands monolayer is disordered and dynamic at an atomic level. Thus, an understanding of the ligands monolayer on a molecular scale is sufficient for many cases. For colloidal nanocrystals stably coordinated with surface ligands, their solution properties are dictated by the ligands monolayer. Experimental and theoretical results reveal that solubility of a nanocrystal-ligands complex is an interplay between the intramolecular entropy of the ligands monolayer and intermolecular interactions of the ligands/nanocrystals. By introducing entropic ligands, solubility of nanocrystal-ligands complexes can be universally boosted by several orders of magnitude, i.e., up to >1 g/mL in typical organic solvents. Molecular environment in the pseudophase surrounding each nanocrystal plays a critical role in its chemical, photochemical, and photophysical properties.For some cases, such as the synthesis of high-quality nanocrystals, all three spatial zones of the nanocrystal surface must be taken into account. By optimizing nanocrystal surface at an atomic-molecular level, semiconductor nanocrystals with monodisperse size and facet structure become available recently through either direct synthesis or afterward facet reconstruction, implying full realization of their size-dependent properties.

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