Au Nanorods Activated the Zn/Ce Composites with Cancer Cell Specific Cytotoxicity for Enhanced Chemodynamic Therapy.

Chemodynamic therapy based on the Fenton reaction has been developed as an extremely promising modality for cancer therapeutics. In this study, a core-shell structure nanoplatform was constructed by a Au nanorod externally encapsulating Ce/Zn-based composites (ACZO). The nanoparticles can catalyze the generation of reactive oxygen species (ROS) under acidic conditions and effectively consume existing glutathione (GSH) to destroy the redox balance within the tumor. Moreover, the decomposition of the nanocomplexes under acidic conditions releases large amounts of zinc ions, leading to zinc overload in cancer cells. The photothermal effect generated by the Au nanorods not only provides photothermal therapy (PTT) but also augments the catalytic reaction and ions action mentioned above. This facile strategy to improve the efficacy of chemodynamic therapy by the photothermal enhancement of catalytic activity and zinc ion release provides a promising perspective for potential tumor treatment.

Endoscopic Submucosal Dissection Criteria for Differentiated-type Early Gastric Cancer Are Applicable to Mixed-type Differentiated Predominant.

BACKGROUND: There is a lack of sufficient evidence on whether mixed-type differentiated predominant early gastric cancer (MD-EGC) can be treated endoscopically by referring to the criteria for differentiated-type early gastric cancer (EGC). This study aims to evaluate the efficacy of endoscopic submucosal dissection (ESD) in MD-EGC. METHODS: Patients with differentiated-type EGC treated with ESD first from January 2015 to June 2021 were reviewed, including MD-EGC and pure differentiated-type EGC (PD-EGC). Clinical data, including the clinicopathological characteristics, resection outcomes of ESD, and recurrence and survival time, were collected, and the difference between MD-EGC and PD-EGC was tested. RESULTS: A total of 48 patients (48 lesions) with MD-EGC and 850 patients (890 lesions) with PD-EGC were included. Compared with PD-EGC, MD-EGC had a higher submucosal invasion rate (37.5% vs. 13.7%, P<0.001) and lymphatic invasion rate (10.4% vs. 0.4%, P<0.001). The rates of complete resection (70.8% vs. 92.5%, P<0.001) and curative resection (54.2% vs. 87.4%, P<0.001) in MD-EGC were lower than those of PD-EGC. Multivariate analysis revealed that MD-EGC (OR 4.26, 95% CI, 2.22-8.17, P<0.001) was an independent risk factor for noncurative resection. However, when curative resection was achieved, there was no significant difference in the rates of recurrence (P=0.424) between the 2 groups, whether local or metachronous recurrence. Similarly, the rates of survival(P=0.168) were no significant difference. CONCLUSIONS: Despite the greater malignancy and lower endoscopic curative resection rate of MD-EGC, patients who met curative resection had a favorable long-term prognosis.

Long-term efficacy of peroral endoscopic myotomy for achalasia under different criteria.

BACKGROUND: Peroral endoscopic myotomy (POEM) has emerged as a widely accepted treatment for achalasia, with limited studies for over 2 years. Additionally, traditional measurements of achalasia after POEM have deficiencies. The study aimed to analyze the long-term outcomes of POEM under different criteria. METHODS: Patients with achalasia who received POEM between November 2012 and March 2021 were recruited. Patients and characteristics were shown, and risk factors related to two novel definitions of recurrence, symptomatic reflux, and reflux esophagitis were analyzed. RESULTS: Three hundred and twenty-one patients were included. At a median follow-up of 52 months, twenty-three failures happened (7.17%) under the modified criterion, and forty-seven failures occurred (14.64%) under the normal standard. Hospitalization (P = 0.027) and esophageal myotomy length (P = 0.039) were significantly associated with long-term efficacy under the modified and normal criteria, respectively. Fifty-two patients (16.20%) reported reflux symptoms and endoscopy performed in 88 patients revealed reflux esophagitis in 22 cases (25.00%). There were no predictors in the analysis of symptomatic reflux and gender (P = 0.010), LESP (P = 0.013), IRP (P = 0.015), and the esophageal myotomy length (P = 0.032) were statistically related to reflux esophagitis. CONCLUSION: POEM is an extremely safe and effective treatment for achalasia with long-term follow-up. Shorter hospitalization and shorter esophageal myotomy length may decrease the incidence of recurrence under the modified and normal criteria, respectively. Long-term outcomes of POEM are unpredictable. No risk factors were related to symptomatic reflux, and male patients with low preoperative LESP and IRP needed relatively shorter esophageal myotomy to prevent reflux esophagitis.

The progression of inorganic nanoparticles and natural products for inflammatory bowel disease.

There is a growing body of evidence indicating a close association between inflammatory bowel disease (IBD) and disrupted intestinal homeostasis. Excessive production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), along with an increase in M1 proinflammatory macrophage infiltration during the activation of intestinal inflammation, plays a pivotal role in disrupting intestinal homeostasis in IBD. The overabundance of ROS/RNS can cause intestinal tissue damage and the disruption of crucial gut proteins, which ultimately compromises the integrity of the intestinal barrier. The proliferation of M1 macrophages contributes to an exaggerated immune response, further compromising the intestinal immune barrier. Currently, intestinal nanomaterials have gained widespread attention in the context of IBD due to their notable characteristics, including the ability to specifically target regions of interest, clear excess ROS/RNS, and mimic biological enzymes. In this review, we initially elucidated the gut microenvironment in IBD. Subsequently, we delineate therapeutic strategies involving two distinct types of nanomedicine, namely inorganic nanoparticles and natural product nanomaterials. Finally, we present a comprehensive overview of the promising prospects associated with the application of nanomedicine in future clinical settings for the treatment of IBD (graphic abstract). Different classes of nanomedicine are used to treat IBD. This review primarily elucidates the current etiology of inflammatory bowel disease and explores two prominent nanomaterial-based therapeutic approaches. First, it aims to eliminate excessive reactive oxygen species and reactive nitrogen species. Second, they focus on modulating the polarization of inflammatory macrophages and reducing the proportion of pro-inflammatory macrophages. Additionally, this article delves into the treatment of inflammatory bowel disease using inorganic metal nanomaterials and natural product nanomaterials.

Ten-Day Vonoprazan-Amoxicillin Dual Therapy as a First-Line Treatment of Helicobacter pylori Infection Compared With Bismuth-Containing Quadruple Therapy.

INTRODUCTION: No study has investigated the efficacy and safety of vonoprazan-amoxicillin dual therapy compared with bismuth quadruple therapy (B-quadruple). This study aimed to evaluate the efficacy and safety of 10-day vonoprazan-amoxicillin dual therapy as a first-line treatment of Helicobacter pylori infection compared with B-quadruple and to explore the optimal dosage of amoxicillin in the dual therapy. METHODS: A total of 375 treatment-naive, H. pylori -infected subjects were randomly assigned in a 1:1:1 ratio into 3 regimen groups including VHA-dual (vonoprazan 20 mg twice/day + amoxicillin 750 mg 4 times/day), VA-dual (vonoprazan 20 mg + amoxicillin 1,000 mg twice/day), and B-quadruple (esomeprazole 20 mg + bismuth 200 mg + amoxicillin 1,000 mg + clarithromycin 500 mg twice/day). Eradication rates, adverse events (AEs), and compliance were compared between 3 groups. RESULTS: The eradication rates of B-quadruple, VHA-dual, and VA-dual were 90.9%, 93.4%, and 85.1%, respectively, by per-protocol analysis; 89.4%, 92.7%, and 84.4%, respectively, by modified intention-to-treat analysis; 88.0%, 91.2%, and 82.4%, respectively, by intention-to-treat analysis. The efficacy of the VHA-dual group was not inferior to the B-quadruple group ( P < 0.001), but VA-dual did not reach a noninferiority margin of -10%. The AEs rates of the B-quadruple group were significantly higher than those of the VHA-dual ( P = 0.012) and VA-dual ( P = 0.001) groups. There was no significant difference in medication compliance among 3 treatment groups ( P = 0.995). CONCLUSIONS: The 10-day VHA-dual therapy provided satisfactory eradication rates of >90%, lower AEs rates, and similar adherence compared with B-quadruple therapy as a first-line therapy for H. pylori infection. However, the efficacy of VA-dual therapy was not acceptable.

Nanoparticles Mediated the Diagnosis and Therapy of Glioblastoma: Bypass or Cross the Blood-Brain Barrier.

Glioblastoma is one of the most aggressive central nervous system malignancies with high morbidity and mortality. Current clinical approaches, including surgical resection, radiotherapy, and chemotherapy, are limited by the difficulty of targeting brain lesions accurately, leading to disease recurrence and fatal outcomes. The lack of effective treatments has prompted researchers to continuously explore novel therapeutic strategies. In recent years, nanomedicine has made remarkable progress and expanded its application in brain drug delivery, providing a new treatment for brain tumors. Against this background, this article reviews the application and progress of nanomedicine delivery systems in brain tumors. In this paper, the mechanism of nanomaterials crossing the blood-brain barrier is summarized. Furthermore, the specific application of nanotechnology in glioblastoma is discussed in depth.

TMEM232 promotes the inflammatory response in atopic dermatitis via the nuclear factor-κB and signal transducer and activator of transcription 3 signalling pathways.

BACKGROUND: Our group previously found that the transmembrane protein 232 (TMEM232) gene was associated with atopic dermatitis (AD) by genome-wide association study and fine mapping study. However, its function is unclear so far. OBJECTIVES: To investigate the roles and mechanisms of TMEM232 in AD. METHODS: The expression of TMEM232 was investigated in skin lesions of patients with AD, the MC903-induced AD mouse model, human primary keratinocytes and immortalized human keratinocyte cell line (HaCaT) cells stimulated with different inflammatory factors. The role of TMEM232 in AD was analysed in HaCaT cells and Tmem232 knockout (Tmem232-/-) mice. Tmem232-specific small interfering RNA (siRNA) was used to evaluate its therapeutic potential in the AD mouse model. RESULTS: The expression of TMEM232 was significantly increased in skin lesions of patients with AD, the MC903-induced AD mouse model and human primary keratinocytes and HaCaT cells stimulated with different inflammatory factors compared with controls. In the presence of MC903, Tmem232-/- mice exhibited significantly reduced dermatitis severity, mast-cell infiltration in the back, and expression of T-helper (Th)1 and Th2-related inflammatory factors in skin tissue compared with wild-type mice. In vitro and in vivo experiments further showed that upregulation of TMEM232 in AD exacerbated the inflammation response through activating the pathway of nuclear factor-κB and signal transducer and activator of transcription (STAT) 3, and was regulated by the interleukin-4/STAT6 axis, which formed a self-amplifying loop. Finally, topical application of Tmem232 siRNA markedly ameliorated AD-like lesions in the AD model. CONCLUSIONS: This study is the first to outline the function of TMEM232. It is involved in regulating inflammation in AD and may be a potential target for AD treatment.

Endoscopic closure of refractory upper GI-tracheobronchial fistulas with a novel occluder: a prospective, single-arm, single-center study (with video).

BACKGROUND AND AIMS: Upper GI-tracheobronchial fistula is a morbid condition with high mortality. It is a challenge for endoscopists because currently available treatments have severe limitations. In this study we assessed the efficacy and safety of an occluder we invented for endoscopic closure of refractory upper GI-tracheobronchial fistulas. METHODS: This was a prospective, single-arm, single-center trial conducted between September 2020 and March 2022. All patients undergoing occluder placement were eligible to enroll. The primary endpoints were clinical success rate (CSR) and complete closure rate (CCR) at 3 months and safety. Secondary efficacy endpoints were technical success rates, CSRs and CCRs at 1 and 6 months, near-complete closure rates, change from baseline in body mass index (BMI), and health-related quality of life (HRQoL) at 1, 3, and 6 months. RESULTS: Twenty-eight patients (mean age, 63.2 years; 23 men) were enrolled. Eighteen through-the-scope occluders (TTSOs) and 10 through-the-overtube occluders (TTOOs) were implanted, with a technical success rate of 100%. The mean procedure time for the TTSO and TTOO groups were 28.0 ± 8.0 minutes and 31.8 ± 7.7 minutes, respectively. The CSRs at 1, 3, and 6 months were 92.9%, 96.4%, and 92.0% and the CCRs were 60.7%, 60.7%, and 60.0%, respectively. The mean BMI at 3 and 6 months and HRQoL at 1, 3, and 6 months were significantly increased compared with baseline (P < .05). Two completely occluded fistulas had 1-sided or complete healing by coverage of granulation tissue and re-epithelialized mucosa at a follow-up of 6 and 12 months. All 14 adverse events were either mild and transient or easily corrected. CONCLUSIONS: Our clinical outcomes suggest that this novel GI occluder is a safe and effective salvage option for patients with refractory upper GI-tracheobronchial fistulas. (Clinical trial registration number: ChiCTR2000038566.).

Effect of Walking Exercise and Intestinal Cleansing Interval on Bowel Preparation Quality, a Single-Blind, Randomized Controlled Trial.

BACKGROUND AND AIMS: High-quality intestinal preparation could promote intestinal cleanliness and lead to more accurate diagnosis, which patients will benefit from. This study aimed to explore the effectiveness of walking exercise and intestinal cleansing interval in bowel preparation before colonoscopy. METHODS: A randomized controlled single blind study was conducted during August 2021 to February 2022. Patients requiring colonoscopy were randomly divided into three groups: 0 step, 5000 steps or 10,000 steps during the intestinal preparation. Participants took the same intestinal cleansing drugs 4-6 h prior to the procedure: 2L-dose polyethylene glycol (PEG). RESULTS: A total of 300 patients were enrolled in the experiment (100 patients per group), and the baseline information of the three groups was close. The BBPS of right (0-step group vs 5,000-step group vs 10,000-step group: 1.78 ± 0.65 vs 1.88 ± 0.54 vs 2.36 ± 0.69, p < 0.001), transverse (0-step group vs 5,000-step group vs 10,000-step group: 2.09 ± 0.78 vs 2.18 ± 0.61 vs 2.59 ± 0.71, p < 0.001) and left (0-step group vs 5,000-step group vs 10,000-step group: 2.01 ± 0.91 vs 2.24 ± 0.59 vs 2.51 ± 0.60, p < 0.001) colon in 10,000-step group were significantly higher than others, respectively. And we also drew the same conclusion in the aspect of ADR. The adverse events and patients' satisfaction had no differences between the two groups. Moreover, intestinal cleansing interval (< 5.12 h) was only effective in BBPS of right colon (p < 0.001) and left colon (p = 0.039). CONCLUSIONS: This study suggested that participants took 10,000-step walking exercise and took PEG 5.12 h prior to the procedure were effective in routine pre-procedure cleanout for standard colonoscopy. NAME OF REGISTRY: Effect of starting time of bowel cleansing and walking exercise after bowel cleansing on bowel preparation: A prospective randomized controlled study. REGISTRATION NUMBER: ChiCTR2100049214.

"M1/M2" Muscularis Macrophages Are Associated with Reduction of Interstitial Cells of Cajal and Glial Cells in Achalasia.

BACKGROUND AND AIMS: Several studies showed muscularis macrophages (MMφ) are associated with GI motility disorders. The purpose of this study was to preliminary explore the association between MMφ and achalasia. METHODS: Tissue samples of the lower esophageal sphincter (LES) high-pressure zone were obtained from 27 achalasia patients and 10 controls. Immunohistochemistry for MMφ, interstitial cells of Cajal (ICC), neuronal nitric oxide synthase (nNOS), and glial cells were conducted. Histological characteristics were compared between groups, and correlation analysis was performed. RESULTS: Fewer ICC was found in achalasia compared with controls (P = 0.018), and the level of M1 macrophages was higher than that in controls no matter in terms of the number or the proportion of M1(P = 0.026 for M1 and 0.037 for M1/MMφ). Statistical differences were found between two groups in terms of proportion of M2 and ratio of M1 to M2 (P = 0.048 for M2/ MMφ and < 0.001 for M1/M2). For the correlation analysis, significant correlations were detected between levels of nNOS, ICC, and glial cells in patients with achalasia (P = 0.026 for nNOS and ICC, 0.001 for nNOS and glial cells, 0.019 for ICC and glial cells). There were significant correlations between M2/MMφ and levels of ICC (P = 0.019), glial cells (P = 0.004), and nNOS (P = 0.135). CONCLUSION: Patients with achalasia had a higher level of M1/M2 ratio in LES and significant correlations were found between M2/MMφ and numbers of ICC and glial cells, which suggested that MMφ were probably associated with occurrence and development of achalasia.

Topical bismuth oxide-manganese composite nanospheres alleviate atopic dermatitis-like inflammation.

Atopic dermatitis (AD) is a common skin disease involving important immune mechanisms. There is an unmet need for a treatment for this condition. Herein, we focused on elucidating the role of Bi2-xMnxO3 nanospheres (BM) in alleviating skin inflammation in AD-like C57BL/6 mice. The BM was fabricated via sacrificial templates and its biosafety was systematically evaluated. The BM was applied topically to skin lesions of AD-like C57BL/6 mice. The phenotypic and histological changes in the skin were examined carefully. The responses of barrier proteins, inflammatory cytokines and cells to BM were evaluated in HaCaT cells and AD mouse models. The data demonstrated that BM treatment alleviated the AD phenotypes and decreased the level of inflammatory factors, while increasing the expression of the barrier proteins filaggrin/involucrin in the skin. BM effectively reduced the expression of phosphorylated STAT6, which in turn reduced the expression of GATA3, and further decreased the differentiation ratio of Th2 cells, thereby reducing the expression of IL-4. In conclusion, topical drug therapy with BM provides a safe and effective treatment modality for AD by reducing IL-4 and increasing barrier proteins.

Advances in the modulation of ROS and transdermal administration for anti-psoriatic nanotherapies.

Reactive oxygen species (ROS) at supraphysiological concentration have a determinate role in contributing to immuno-metabolic disorders in the epithelial immune microenvironment (EIME) of psoriatic lesions. With an exclusive focus on the gene-oxidative stress environment interaction in the EIME, a comprehensive strategy based on ROS-regulating nanomedicines is greatly anticipated to become the mainstay of anti-psoriasis treatment. This potential therapeutic modality could inhibit the acceleration of psoriasis via remodeling the redox equilibrium and reshaping the EIME. Herein, we present a marked overview of the current progress in the pathomechanisms of psoriasis, with particular concerns on the potential pathogenic role of ROS, which significantly dysregulates redox metabolism of keratinocytes (KCs) and skin-resident or -infiltrating cells. Meanwhile, the emergence of versatile nanomaterial-guided evolution for transdermal drug delivery has been attractive for the percutaneous administration of antipsoriatic therapies in recent years. We emphasize the underlying molecular mechanism of ROS-based nanoreactors for improved therapeutic outcomes against psoriasis and summarize up-to-date progress relating to the advantages and limitations of nanotherapeutic application for transdermal administration, as well as update an insight into potential future directions for nanotherapies in ROS-related skin diseases.

A multifunctional composite hydrogel as an intrinsic and extrinsic coregulator for enhanced therapeutic efficacy for psoriasis.

BACKGROUND: Psoriasis is a chronic relapsing immunological skin disease characterized by multiple cross-talk inflammatory circuits which are relevantly associated with abnormal cross-reactivity between immune cells and keratinocytes (KCs). It may be inadequate to eradicate complicated pathogenesis only via single-mode therapy. To provide optimal combinatory therapeutics, a nanocomposite-based hydrogel was constructed by loading methotrexate (MTX) into ZnO/Ag to realize combined multiple target therapy of psoriasis. RESULTS: In this composite hydrogel, ZnO hybrid mesoporous microspheres were utilized both as drug carriers and reactive oxygen species (ROS)-scavenging nanoparticles. A proper amount of Ag nanoparticle-anchored ZnO nanoparticles (ZnO/Ag) was functionalized with inherent immunoregulatory property. The experiments showed that ZnO/Ag nanoparticles could exhibit a self-therapeutic effect that was attributed to reducing innate cytokine profiles by inactivating p65 in proinflammatory macrophages and abrogating secretion of adaptive cytokines in KCs by downregulating ROS-mediated STAT3-cyclin D1 signaling. A preferable antipsoriatic efficacy was achieved via topical administration of this hydrogel on the imiquimod (IMQ)-induced psoriasis mice model, demonstrating the superior transdermal delivery and combined enhancement of therapeutic efficacy caused by intrinsic nanoparticles and extrinsic MTX. CONCLUSION: This composite hydrogel could serve as a multifunctional, nonirritating, noninvasive and effective transcutaneous nanoagent against psoriasis.

Highly Active Zinc Sulfide Composite Microspheres: A Versatile Template for Synthesis of a Family of Hollow Nanostructures of Sulfides.

Hollow nanostructures of metal sulfides have gained tremendous attention in catalysis, biomedicine, and energy storage and conversion owing to their intriguing structural features and fascinating physicochemical properties. Here, we reported a hard template-engaged cation exchange method to fabricate a family of binary or ternary metal sulfide (CuS, Ag2S, Bi2S3, CuxBi1-xS, ZnxCo1-xS, ZnxCd1-xS, ZnxNi1-xS, and ZnxMn1-xS) hollow microspheres via adjusting the reaction kinetic parameters including solvent and temperature in the presence of unique ZnS composite microspheres. Particularly, the shell layer thickness of metal sulfide hollow microspheres could be modulated by manipulating the reaction temperature during the cation exchanging procedure. Meanwhile, the desired elementary composition of ternary metal sulfide hollow microspheres could be achieved by varying the mole ratio and species of the metal source. This synthetic strategy could be extended to rationally design and construct other metal sulfide hollow nanostructures and provide a deep insight into the nucleation and growth process of the metal sulfide hollow microspheres with well-controlled composition and microstructures.

Recent Advances in Controlled Synthesis of Upconversion Nanoparticles and Semiconductor Heterostructures.

It's of great importance for construction of upconversion nanoparticles (UCNPs)/semiconductor heterostructures activated by near infrared light, which have gained worldwide research interests owing to important applications in photocatalysis, solar cells, nanomedicine, and etc. In this review, we highlight the synthetic strategies developed to fabricate upconversion nanoparticles based heterostructures, such as chemical epitaxial growth method, electrospinning technique, self-assembly method, hydrothermal method, and etc. Numerous examples are given concerning the use of the strategies to fabricate various microstructures/nanostructures incorporated with UCNPs and semiconductors materials. The latest advances and perspectives in the synthetic strategies and preparation of this kind of composite nanostructures are made.

Recent Development on Controlled Synthesis of Metal Sulfides Hollow Nanostructures via Hard Template Engaged Strategy: A Mini-Review.

In this mini-review, we highlighted the recent progresses in the controlled synthesis of metal sulfides hollow nanostructures via hard template technique. After a brief introduction about the formation mechanism of the inorganic hollow nanostructures via hard template technique, the discussions primarily focused on the emerging development of metal sulfides hollow nanostructures. Various synthetic strategies were summarized concerning the use of the hard template engaged strategies to fabricate various metal sulfides hollow nanostructures, such as hydrothermal method, solvothermal method, ion-exchange, sulfidation or calcination etc. Finally, the perspectives and summaries have been presented to demonstrate that a facile synthetic technique would be widely used to fabricate metal sulfides hollow nanostructures with multi-shells and components.

Autophagic blockage by bismuth sulfide nanoparticles inhibits migration and invasion of HepG2 cells.

The biological effects of nanoparticles are of great importance for the in-depth understanding of safety issues in biomedical applications. Induction of autophagy is a cellular response after nanoparticle exposure. Bismuth sulfide nanoparticles (Bi2S3 NPs) are often used as a CT contrast agent because of their excellent photoelectric conversion ability. Yet there has been no previous detailed study other than a cell toxicity assessment. In this study, three types of Bi2S3 NPs with different shapes (Bi2S3 nano rods (BSNR), hollow microsphere Bi2S3 NPs (BSHS) and urchin-like hollow microsphere Bi2S3 NPs (ULBSHS)) were used to evaluatecytotoxicity, autophagy induction, cell migration and invasion in human hepatocellular carcinoma cells (HepG2). Results showed that all three Bi2S3 NPs lead to blockage in autophagic flux, causing p62 protein accumulation. The cell death caused by these Bi2S3 NPs is proved to be autophagy related, rather than related to apoptosis. Moreover, Bi2S3 NPs can reduce the migration and invasion in HepG2 cells in an autophagy-dependent manner. ULBSHS is the most cytotoxic among three Bi2S3 NPs and has the best tumor metastasis suppression. These results demonstrated that, even with relatively low toxicity of Bi2S3 NPs, autophagy blockage may still substantially influence cell fate and thus significantly impact their biomedical applications, and that surface topography is a key factor regulating their biological response.

Sequential Growth of High Quality Sub-10 nm Core-Shell Nanocrystals: Understanding the Nucleation and Growth Process Using Dynamic Light Scattering.

Monodisperse sub-10 nm core-shell nanocrystals have been extensively studied owing to their important applications in catalysis, bioimaging, nanomedicine, and so on. In this work, an amorphous shell component crystallization strategy has been proposed to prepare high quality sub-10 nm NaYF4:Yb/Er@NaGdF4 core-shell nanocrystals successfully via a sequential growth process. The dynamic light scattering technique has been used to investigate the secondary nucleation and growth process forming the core-shell nanocrystals. The size and morphology evolution of the core-shell nanocrystals reveals that the secondary nucleation of the shell component is unavoidable after hot-injecting the shell precursor at high temperatures, which was followed by dissolution and recrystallization (an Ostwald ripening process) to partially produce the core-shell nanocrystals. The present study demonstrates that the size of seed nanocrystals and the injection temperature of the shell component precursor play a vital role in the formation of core-shell nanostructures completely. This work will provide an alternative strategy for precisely controlling the fabrication of sub-10 nm core-shell nanostructures for various applications.

Large-Scale Ligand-Free Synthesis of Homogeneous Core-Shell Quantum-Dot-Modified Cs4PbBr6 Microcrystals.

An organic ligand-free solution method is developed for preparing homogeneous core-shell quantum-dot (QD)-modified pure Cs4PbBr6 microcrystals on a large scale (∼12 g) at room temperature. The ligand-free Cs4PbBr6 microcrystals show a high green photoluminescence quantum yield of 76% with 360 nm of excitation light, which is attributed to their unique microarchitecture, with several features including quantum confinement of the outer QDs, stability of the inner Cs4PbBr6 microcrystals, improved light trapping, and interfacial recombination. UV-vis-near-IR and photoluminescence analyses provide valued evidence to support the ligand-free Cs4PbBr6 with synergy between the QDs and microcrystals.