Long-term follow-up of owned, free-roaming dogs in South Africa naturally exposed to Babesia rossi

Babesia rossi is an important, tick-borne intraerythrocytic protozoan parasite; however, its natural history and epidemiology is poorly understood. Babesia rossi is the most virulent Babesia sp. in domestic dogs and is generally considered to cause severe babesiosis, which is fatal if left untreated. However, subclinical infections and mild disease from B. rossi have been reported, although the clinical progression of these cases was not reported. Therefore, to better understand B. rossi under field conditions, we evaluated its clinical progression and seroprevalence in an owned, free-roaming dog population in Zenzele, South Africa, where the parasite is endemic and prevention is not routine. The entire dog population in Zenzele was monitored intensively at the individual level from March 2008 until April 2014, primarily for a longitudinal study on rabies control. Subsequent evaluation of B. rossi comprised analyses of clinical and laboratory data collected from the Zenzele dog population during the 6 year study period. A substantial proportion (31% (n = 34)) of 109 dogs (randomly selected from every available dog in February/March 2010 older than ~6-8 weeks (n = 246)) tested by Indirect Fluorescent Antibody Test had seroconverted strongly to B. rossi. All 34 dogs were generally consistently healthy adults, determined from regular clinical examinations between March 2008 and April 2014. Blood smear examinations at multiple time points between July 2009 and February 2011 were also undertaken for almost all of these (34) seropositive dogs and all those tested were consistently negative for Babesia spp. Subclinical infections and mild disease were also the main findings for a separate group of 18 dogs positive for Babesia spp. on blood smear examination and confirmed to be infected with B. rossi by Polymerase Chain Reaction - Reverse Line Blot. Almost all of these dogs were positive at only one time point from repeat blood smear examinations between July 2009 and February 2011. We suggest that these observations are consistent with immunity acquired from repeated, low-level exposure to the parasite, generating transient subclinical infections or mild disease. Should this be the case, the use of tick control, particularly in adult dogs in free-roaming populations in B. rossi endemic regions, should be carefully considered.

Randomized clinical trial of intraoperative dexmedetomidine to prevent delirium in the elderly undergoing major non-cardiac surgery

Background

Delirium is common in elderly patients after surgery and is associated with poor outcomes. This study aimed to investigate the impact of intraoperative dexmedetomidine on the incidence of delirium in elderly patients undergoing major surgery.

Methods

This was a randomized double-blind placebo-controlled trial. Elderly patients (aged 60 years or more) scheduled to undergo major non-cardiac surgery were randomized into two groups. Patients in the intervention group received a loading dose of dexmedetomidine 0·6 μg/kg 10 min before induction of anaesthesia followed by a continuous infusion (0·5 μg per kg per h) until 1 h before the end of surgery. Patients in the control group received volume-matched normal saline in the same schedule. The primary outcome was the incidence of delirium during the first 5 days after surgery. Delirium was assessed with the Confusion Assessment Method (CAM) for non-ventilated patients and CAM for the Intensive Care Unit for ventilated patients.

Results

In total, 309 patients who received dexmedetomidine and 310 control patients were included in the intention-to-treat analysis. The incidence of delirium within 5 days of surgery was lower with dexmedetomidine treatment: 5·5 per cent (17 of 309) versus 10·3 per cent (32 of 310) in the control group (relative risk (RR) 0·53, 95 per cent c.i. 0·30 to 0·94; P = 0·026). The overall incidence of complications at 30 days was also lower after dexmedetomidine (19·4 per cent (60 of 309) versus 26·1 per cent (81 of 310) for controls; RR 0·74, 0·55 to 0·99, P = 0·047).

Conclusion

Intraoperative dexmedetomidine halved the risk of delirium in the elderly after major non-cardiac surgery. Registration number: ChiCTR-IPR-15007654 (www.chictr.org.cn).

Electron transfer in a semiconductor heterostructure interface through electrophoretic deposition and a linker-assisted method

Modulating the heterostructured interface of semiconductor nanocrystals is being widely explored to enhance the charge transfer rate in photoelectrochemical cells.

Beneficial effects of xenon inhalation on behavioral changes in a valproic acid-induced model of autism in rats

BACKGROUND

Xenon (Xe) is a noble gas that has been used for the last several decades as an anesthetic during surgery. Its antagonistic effect on glutamate subtype of NMDA (N-methyl-D-aspartate) receptors resulted in evaluation of this gas for treatment of CNS pathologies, including psychoemotional disorders. The aim of this study was to assess the behavioral effects of acute inhalation of subanesthetic concentrations of Xe and to study the outcomes of Xe exposure in valproic acid (VPA)-induced rodent model of autism.

METHODS

We have conducted two series of experiments with a battery of behavioral tests aimed to evaluate locomotion, anxiety- and depression-like behavior, and social behavior in healthy, VPA-treated and Xe-exposed young rats.

RESULTS

We have shown that in healthy animals Xe exposure resulted in acute and delayed decrease of exploratory motivation, partial decrease in risk-taking and depressive-like behavior as well as improved sensorimotor integration during the negative geotaxis test. Acute inhalations of Xe in VPA-exposed animals led to improvement in social behavior, decrease in exploratory motivation, and normalization of behavior in forced-swim test.

CONCLUSION

Behavioral modulatory effects of Xe are probably related to its generalized action on excitatory/inhibitory balance within the CNS. Our data suggest that subanesthetic short-term exposures to Xe have beneficial effect on several behavioral modalities and deserves further investigation.

Apoptotic and Proteolytic Attributes and Metabolomic Changes in Postmortem Muscles from Pigs Subjected to Post-Weaning Transport at Different Seasons

ObjectivesPost-weaning transport of pigs was commonly practiced in the swine industry, however, adversely impact animal growth and well-being due to concurrent stress from weaning and transport. Further, our recent study found that post-weaning transport may have long-term effects on final pork quality attributes in terms of inferior texture and water-holding capacity. Heat shock proteins (HSPs) are anti-apoptotic chaperone proteins, protecting against apoptosis under a variety of cell death stimuli including postmortem muscle conversion process. While a potential role of apoptosis in meat tenderization has been proposed, how early life stress influences apoptotic/proteolytic process and metabolism of postmortem muscles is largely unknown. Thus, the study objective was to evaluate apoptotic and proteolytic attributes and metabolomic changes in postmortem muscles of market weight pigs exposed to early life transport/weaning stress at two seasons.Materials and MethodsTwo repetitions of newly weaned pigs (N = 480) were transported for 12 h in a trailer truck during July 2016 (SUMMER) and April 2017 (SPRING) in north-central Indiana. Upon reaching market weight, 10 animals were randomly chosen from each season and slaughtered in January 2017 and September 2017, respectively. Pairs of longissimus dorsi and psoas major muscles from each carcass were separated at 1d and 7d postmortem. Proteolytic and apoptotic factors including desmin, troponin T, calpain 1, HSP27, and aβ-crystallin were quantified using Western-blot assays, and mitochondria membrane permeability (MMP) was evaluated. Metabolome profiles of 1d samples were analyzed using the GC-TOF-MS/MS platform. Multivariate analyses PCA and PLS-DA were used to determine changes of metabolites. Data were analyzed using PROC MIXED of SAS to compare the traits across season, muscle, and aging effects.ResultsPreviously, SUMMER pigs were reported showing decreased body weight, muscling, and fat deposition, as well as increased shear force and water loss during aging. In the present study, SPRING muscles exhibited increases in calpain 1 autolysis and structural protein degradation, coincided with accelerated apoptosis shown as higher MMP compared to the SUMMER counterparts (P < 0.05). Moreover, PCA and PLS-DA clustering indicated distinct metabolome profiles affected by season and muscle. Seasonal effect mainly altered lipid, glucose, and nitrogen metabolism. A group of 16C to 18C fatty acids were increased in SPRING, probably due to increased lipid anabolism during warm growing/finishing season. Changes of urea, ornithine, aspartic acid, and 5’methylthioadenosine suggested increased amino acid catabolism in SUMMER, corroborating the decreased lean and fat accretion. Seasonal changes of key metabolites related to stress response, including histidine, GABA, and ascorbic acid, suggested increased stress defense in SUMMER pigs, which implied the suppression of apoptotic and proteolytic activities.ConclusionTaken together, SUMMER pigs showed suppressed onset of apoptosis with compromised growth and meat quality, possibly due to alternations in seasonal metabolic response. This may in turn affect the proteolytic potential of early postmortem muscles. Further studies elucidating the involvement of apoptotic process in proteolytic activities in postmortem muscles should be warranted.

H19 promotes the proliferation of osteocytes by inhibiting p53 during fracture healing

OBJECTIVE

We explored the possible mechanism underlying the expression change of H19 during fracture healing.

MATERIALS AND METHODS

A total of 18 male SD mice aged from 6-8 weeks old (18.5-24.6 g) were selected to establish tibial fracture models. The left tibia undergoing sham surgery was considered as the control group, and the right tibia undergoing sawing treatment was considered as the experimental group. The control tibia and fracture tibia from three mice were harvested at six time points after operation, respectively. QRT-PCR was utilized to detect the changes of H19 and p53 mRNA expression.

RESULTS

Compared with the control group, the expression of H19 in the experimental group was significantly increased at 4, 8, and 12 d. However, there was no significant difference in the expression of H19 between the experimental group and the control group at 16, 20, and 24 d. The proliferation of chondrocytes and osteoblasts from mouse and human was significantly inhibited, and the apoptosis was significantly increased after interference of H19. As p19 plays important roles in diverse biological process, we detected the expression level of p19 after inference of H19. In addition, knockdown of H19 significantly up-regulated the expression of p53 in osteoblast cell lines, while the down-regulation of p53 expression reversed the proliferation of osteoblasts.

CONCLUSIONS

H19, as a molecular marker for promoting fracture healing, promote the proliferation of osteocytes by inhibiting the expression of p53.

Ageing affects the proliferation and mineralization of rat dental pulp stem cells under inflammatory conditions

AIM

To comparatively evaluate changes in the proliferation and mineralization abilities of dental pulp stem cells (DPSCs) from juvenile and adult rats in a lipopolysaccharide (LPS)-induced inflammatory microenvironment to provide a theoretical basis for the age-related differences observed in DPSCs during repair of inflammatory injuries.

METHODOLOGY

DPSCs were isolated from juvenile (JDPSCs) and adult rats (ADPSCs), and senescence-associated β-galactosidase staining was used to compare senescence between JDPSCs and ADPSCs. Effects of LPS on JDPSCs and ADPSCs proliferation were investigated by cell counting kit-8 assays and flow cytometry. Alizarin red staining, quantitative reverse transcription polymerase chain reaction and Western blot assay were used to examine the effects of LPS on mineralization-related genes and proteins in JDPSCs and ADPSCs. Immunohistochemistry was used to compare interleukin-1β (IL-1β) and osteocalcin (OCN) expression in the pulpitis model. Unpaired Student's t-tests and one-way anova were used for statistical analysis.

RESULTS

DPSCs were isolated from juvenile and adult rat dental pulp tissues. At low concentrations (0.1-1 μg mL^-1 ), LPS significantly promoted the proliferation of JDPSCs (P < 0.01) and ADPSCs (P < 0.01 or P < 0.05), with the effect being stronger in JDPSCs than in ADPSCs. In addition, mineralized nodules and the expression of mineralization-related genes (OCN, DSPP, ALP, BSP) increased significantly after stimulation with LPS (0.5 μg mL^-1 ) in JDPSCs and ADPSCs (P < 0.01 or P < 0.05), and JDPSCs displayed a more obvious increase than ADPSCs. Western blots revealed OCN and ALP expression levels in JDPSCs treated with LPS were significantly upregulated (P < 0.05); meanwhile, ALP expression in ADPSCs increased slightly but significantly (P < 0.05), and OCN expression was not affected. Finally, IL-1β expression was significantly higher (P < 0.05) and OCN expression was significantly lower (P < 0.05) in the inflamed dental pulp of adult rats than in juvenile rats.

CONCLUSIONS

A certain degree of inflammatory stimulation promoted the proliferation and mineralization of DPSCs; however, this effect declined with age. The DPSCs of adult donors in an inflammatory microenvironment have a weaker repair ability than that of juvenile donors, who are better candidates for tissues damage repair.

Abstract P2-01-13: The splicing factor PHD finger protein 5A inhibits apoptosis to promote breast cancer progression

Background: All the widely accepted hallmarks of cancer are known to be affected by aberrant splicing (AS), and splicing dysregulation itself is considered a valuable therapeutic target. Understanding the AS that promote cancer progression is crucial for the development of effective strategies for treating breast cancer.

Methods: An in vivo CRISPR screen targeting RNA-binding proteins (RBPs) was performed to reveal the key splicing modulator (PHD finger protein 5A, PHF5A) of breast tumor progression. Immunohistochemistry method and survival analysis were performed using a tissue microarray (TMA) containing 450 breast carcinoma. Proliferation, transwell migration and in vivo tumor formation assays were utilized to assess the biological role of PHF5A. RNA sequencing and RT-PCR assay were used to identify PHF5A-regulated AS events in breast cancer cells. Biological functions and molecular pathways of the affected genes were investigated through a gene ontology (GO) analysis. Flow cytometry and Western blot analysis were used for apoptotic assessments. The correlation between PHF5A expression and AS events was further analysed using mRNA-Seq data of 40 paired breast cancer and adjacent normal breast tissues. And the correlation between the levels of PHF5A and cleaved caspase-3 were evaluated in the TMA.

Results: According to RNA sequencing analysis of MCF10 cell series (MCF10A, MCF10AT, MCF10DCIS and MCF10CA1a), 159 RBPs were found to be up-regulated in cancer cells compared with non-cancer cells. And the CRISPR screen targeting these 159 RBPs systematically identified highest-ranking genes including PHF5A. In TMA cohort, high PHF5A expression was correlated with poor disease-free survival. PHF5A is frequently up-regulated in breast cancer and is essential for cancer cell proliferation, migration and tumor formation. Knockdown of PHF5A induces genome-wide AS events. The RT-PCR assay of MCF10CA1a cells showed that splicing changes of nine arbitrarily selected target genes were all modulated by PHF5A. GO analysis showed that PHF5A-regulated AS events were involved in apoptotic and anti-apoptotic pathways, among which FAS-activated serine/threonine kinase (FASTK) AS showed significant PSI (percent spliced in) difference. PHF5A knockdown appeared to switch full-length FASTK (FASTK-L) to an intron 5-retained variant (herein termed FASTK short, FASTK-S) in MCF10CA1a cells. The knockdown of PHF5A resulted in cleavage of caspase-3 and poly-ADP-ribose polymerase and conversion of the FASTK-L (61 kDa) and FASTK-S (42 kDa) proteins. Intriguingly, cells transduced with exogenous FASTK-S showed the most significant apoptotic effect, whereas the FASTK-L group presented a decreased apoptotic effect. The PHF5A ratios of paired non-tumor to tumor tissue were negatively correlated with the FASTK PSI differences between non-tumor and tumor tissues. A strong negative correlation was found between the PHF5A and cleaved caspase-3 levels in TMA.

Conclusions: PHF5A depletion sensitizes cancer cells to apoptotic signaling partially through AS-mediated FASTK isoform conversion. This apoptotic suppressor plays a key role in breast cancer progression and acts as a prognostic indicator, and should be critically considered for optimization of the current therapeutic strategy.

Citation Format: Zheng Y-Z, Xue M-Z, Shen H-J, Li X-G, Ma D, Gong Y, Hu X, Shao Z-M. The splicing factor PHD finger protein 5A inhibits apoptosis to promote breast cancer progression [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-01-13.

Abstract P3-08-11: Multi-omics profiling reveals distinct molecular features in young and elderly triple negative breast cancer

Purpose

Age at breast cancer diagnosis not only predicts clinical outcome, but also indicates distinct molecular features thus we can choose the most appropriate treatment strategies. Yet little is known about the molecular profile of young and elderly triple negative breast cancers (TNBCs).

Methods

Clinical, genomic and transcriptome features of young (&lt;40 year-olds) and elderly (≥65 year-olds) TNBC patients were studied in a cohort of 473 TNBCs from Fudan University Shanghai Cancer Center.

Results

In this study, 50, 354 and 69 patients were &lt;40, 40–64 and ≥65 years of age, respectively. Young TNBCs had more relapse or metastasis within the first 2 years after surgery (P=0.036) which was also significant in the basal-like subgroup (P=0.004), while elderly TNBCs were more likely to be luminal androgen receptor (LAR) subtype (46%) harboring frequent PIK3CA and KMT2C/KMT2D somatic mutations, with more fibrosis or mesenchymal-like (MES) subtype (in the basal-like subgroup) and featured by significantly lower Ki-67 index. Gene set enrichment analyses revealed that young TNBCs showed elevated expression of genes involved in cell cycle, nucleotide metabolism and DNA damage repair. In further discussion on nucleotide metabolism, TYMS, a crucial gene encoding thymidylate synthase while is also the target of fluorouracil and capecitabine, were identified to be enriched in young TNBCs independent of molecular subtype in both our cohort (adjusted P&lt;0.001) and METABRIC (adjusted P=0.027). We next studied DNA damage features and found that while TNBCs of different age groups had comparable somatic mutation load, their mutations had distinct generation mechanism that homologous recombination deficiency (HRD) related signature and Aging related signature tend to be enriched in younger and elder patients, respectively. We also observed higher germline BRCA1 mutation rate in young TNBCs (23%). Interestingly, while germline BRCA2 mutation rate was comparable among the groups, copy number (CN) loss of Chr13q13 (with BRCA2 in the 'peak') was almost exclusively found in young patients (adjusted P&lt;0.05). We also found enriched CN loss at Chr15q13 (with FAN1 in the 'peak') and CN amplification at Chr1p34 (with KDM4A in the 'peak') in young patients. These two events significantly affected the expression levels of FAN1 and KDM4A, respectively, and were both corrected with genomic based HRD indexes.

Conclusions

TNBCs of different age had distinct clinical and molecular features. We should pay attention to that nearly half of the TNBCs diagnosed at 65 years-old or later were not basal-like cancers but a special group with positive AR staining. Taking together with the higher fibrosis/MES proportion in elderly TNBC, we should reconsider the benefit of specific treatment strategies (like neoadjuvant chemotherapy) in these patients. The young TNBCs were characterized by activated cell cycle, elevated nucleotide metabolism (especially TYMS expression and corresponding pyrimidine metabolism) and enhanced DNA damage (especially HRD). These molecular features supported the aggressive phenotypes of young TNBC, while also provide us with potential therapeutic strategies.

Citation Format: Ma D, Jiang Y-Z, Xie M-D, Xiao Y, Zhao S, Shao Z-M. Multi-omics profiling reveals distinct molecular features in young and elderly triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-08-11.

Abstract P3-07-07: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Jiang Y-Z, Ma D, Suo C, Shi J, Xue M, Stover DG, Verschraegen C, Kaklamani V, Wang P, Shi L, Huang W, Shao Z-M. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-07-07.

Abstract P4-06-24: Microenvironment heterogeneity of triple-negative breast cancer reveals distinct immune escape mechanisms and potential driver events

Background The microenvironment phenotypes strongly affect the immunotherapeutic strategies for triple-negative breast cancer (TNBC). Although the multi-omics profile of TNBC has been comprehensively characterized, few studies have focused on the microenvironment phenotypes of TNBC.

Methods With multi-omics data for the largest single-center TNBC cohort (n=386), we first established a TNBC-specific microenvironment cell signature. We further used single sample gene set enrichment analysis to calculate the relative number of microenvironment cell subsets in each sample. Then, we performed k-means clustering to classify the TNBC microenvironment phenotypes into heterogeneous clusters. Furthermore, we systematically analyzed the extrinsic and intrinsic immune escape mechanisms of different TNBC microenvironment clusters. In addition, we explored genomic alterations that might decrease immune infiltration in certain TNBC microenvironment clusters.

Results We classified the TNBC microenvironment phenotypes into three heterogeneous clusters. Cluster 1 (type 1 “cold tumor”) had low microenvironment cells infiltration. Cluster 2 (type 2 “cold tumor”) was characterized by resting innate immune cells, fibroblasts and endothelial cells infiltration. Cluster 3 (“hot tumor”) was featured by adaptive immune cells infiltration. Analysis of immune escape mechanism revealed that an incapability to attract innate immune cells (resulting in failure of adaptive immunity) led to immune escape of cluster 1. The chemotaxis but inactivation of innate immunity (also leading to failure of adaptive immunity) and low tumor antigen burden resulted in immune escape of cluster 2. High expression of immune checkpoint molecules contributed to immune escape of cluster 3. In addition, we found that tumor infiltrating lymphocytes (TILs) were positively correlated with immune checkpoint molecules expression, while mutation load was negatively correlated with those indicators in triple-negative breast cancer. Analysis of enrichment pathways, mutations and somatic copy number variations between the “cold tumor” and “hot tumor” clusters revealed that amplification of MYC and activation of MYC-related pathways might decrease the immune infiltration of cluster 1. Mutations in PI3K-AKT pathway members and activation of fibroblasts-related pathways might decrease the immune infiltration of cluster 2.

Conclusion Utilizing the largest single-center TNBC cohort with multi-omics data, our study first revealed the heterogeneity of the TNBC microenvironment, with translational significance both clinically and biologically. First, we identified a subtype of “hot tumor” in TNBC (cluster 3), for which immune checkpoint blockers (ICBs) might be effective. TILs and immune checkpoint molecules expression but not mutation load might predict the efficacy of ICBs. Second, we presumed some genomic alterations that might drive “cold tumor” formation in TNBC. Our study represents a step toward personalized immunotherapy for TNBC patients.

Key Words triple-negative breast cancer, multi-omics, microenvironment heterogeneity, immune escape

Citation Format: Xiao Y, Ma D, Zhao S, Jiang Y-Z, Shao Z-M. Microenvironment heterogeneity of triple-negative breast cancer reveals distinct immune escape mechanisms and potential driver events [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-06-24.

Abstract P2-08-33: A novel seven-gene signature predicts prognosis in early-stage triple-negative breast cancer

Purpose:

Chemotherapy remains the only systemic treatment option for patients with triple-negative breast cancer (TNBC). However, due to the heterogeneity of TNBC, not all patients benefit from chemotherapy, especially those with early-stage disease. In order to improve prognostic assessment and reduce unnecessary adjuvant systemic therapy in these patients, we have developed a novel seven-gene signature.

Experimental Design:

With the ComBat method, we integrated the results from 150 transcriptome microarrays samples and 246 RNA-seq samples of early-stage TNBC patients, and identified mRNAs associated with recurrence-free survival (RFS) using Lasso-Cox model, We further analyzed these TNBC samples and compared them with 60 paired normal breast tissues (40 samples from RNA-seq and 20 samples from microarrays) to identify tumor-specific mRNAs. Twenty-one overlapped mRNAs of the RFS-associated mRNAs and the tumor-specific mRNAs are selected as candidate mRNAs. An additional 371 samples of frozen primary tumors were then collected from early-stage TNBC patients (mean follow-up of 45 months) and randomly divided into two sets: a training set (n = 186) and a validation (n = 185) set. Expression level of candidate mRNAs in these samples were measured using RT-qPCR assays, and a seven-gene signature was built through all subset regression in the training set. The prognostic and predictive accuracy of our signature was tested in the validation set and other public databases (GSE5327, GSE2034 and METABRIC).

Results:

Twenty-one candidate mRNAs were identified in early-stage TNBC patients, from which we developed a novel seven-gene signature (recurrence risk score [mRNA signature] = 1.108*TMEM101 - 0.213*KRT5 - 0.315*ACAN - 0.464*LCA5 + 0.446*RPP40 - 0.373*LAGE3 - 0.257*CDKL2). Patients in the training set were classified into high- or low-risk group based on our seven-gene signature and an optimum cut-off score derived from x-tile. The patients in high-risk group were more likely to suffer from recurrence (HR, 2.718; 95% confidence interval [CI], 1.928–3.726, P= 0.001), and a time-dependent receiver operating curve showed that the seven-gene mRNA signature had a better prognostic value than the clinicopathologic risk factors in both training set and validation set. The prognostic and predictive accuracy of the signature was also validated in the METABRIC and two other public GEO databases (GSE5327 and GSE2034). The time-dependent receiver operating curve showed that this signature had an area under the curve (AUC) of 0.742 (95% CI, 0.705-0.773) in METABRIC, 0.716 (95% CI, 0.682-0.739) and 0.723 (95% CI, 0.683-0.756) in GSE5327 and GSE2034 respectively.

Conclusion:

In this study, we developed a novel seven-gene signature which can provide additional prognostic information and may guidance in identifying early-stage TNBC patients eligible for adjuvant therapy or reduction of chemotherapy. To our knowledge, this is the first study investigating the prognostic potential of mRNA signature in early-stage triple-negative breast cancer. Our novel signature may provide an opportunity for de-escalating treatment in early-stage TNBC patients in the future.

Citation Format: Ren Y, Jiang Y, Zuo W, Xu X, Jin X, Ma D, Shao Z. A novel seven-gene signature predicts prognosis in early-stage triple-negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-33.

Air-Processed, Stable Organic Solar Cells with High Power Conversion Efficiency of 7.41

High efficiency, excellent stability, and air processability are all important factors to consider in endeavoring to push forward the real-world application of organic solar cells. Herein, an air-processed inverted photovoltaic device built upon a low-bandgap, air-stable, phenanthridinone-based ter-polymer (C₁₅₀ H₂₁₈ N₆ O₆ S₄ )_n (PDPPPTD) and [6,6]-phenyl-C₆₁ -butyric acid methyl ester (PC₆₁ BM) without involving any additive engineering processes yields a high efficiency of 6.34%. The PDPPPTD/PC₆₁ BM devices also exhibit superior thermal stability and photo-stability as well as long-term stability in ambient atmosphere without any device encapsulation, which show less performance decay as compared to most of the reported organic solar cells. In view of their great potential, solvent additive engineering via adding p-anisaldehyde (AA) is attempted, leading to a further improved efficiency of 7.41%, one of the highest efficiencies for all air-processed and stable organic photovoltaic devices. Moreover, the device stability under different ambient conditions is also further improved with the AA additive engineering. Various characterizations are conducted to probe the structural, morphology, and chemical information in order to correlate the structure with photovoltaic performance. This work paves a way for developing a new generation of air-processable organic solar cells for possible commercial application.

Ce4+ as a facile and versatile surface modification reagent for templated synthesis in electrical applications

Surface modification for templated synthesis is crucial to achieving three-dimensional (3D) architectured materials for catalysis, photonics, energy storage, etc. However, the existing facile and versatile modification methods (e.g. with dopamine and catechol) generate modification layers that are unstable in harsh environments. These methods are thus unsuitable for electrical applications. Here we report that Ce4+ can act as an effective surface modification reagent for a broad range of substrates (chitinous butterfly wings, carbon paper, nickel foam, and polyethylene terephthalate planks) with various structural features owing to its strong oxidizing ability and Lewis acid nature. The modification yields discrete CeO2 seed layers on substrate surfaces in ca. 0.25-2 h, important for the subsequent conformal growth of CeO2 nanoparticles, Ni(OH)2 nanowires, FeOOH nanosheets, and WO3 nanosheets into 3D architectured materials. The conformally synthesized FeOOH on nickel foam (NF) yields an overpotential of 241 mV at 10 mA cm-1 for an oxygen evolution reaction. This value is comparable to a typical catalyst Ni(Fe)OOH-NF for which the Ni/Fe ratio must be well-optimized. This facile and versatile strategy might have broad applications in the conformal fabrication and application of 3D architectured materials, especially when applied in electrical applications of architectured materials (e.g. Li-ion battery).

Multifunctional Self-Assembled Supernanoparticles for Deep-Tissue Bimodal Imaging and Amplified Dual-Mode Heating Treatment

Developing multifunctional therapeutic and diagnostic (theranostic) nanoplatforms is critical for addressing challenging issues associated with cancers. Here, self-assembled supernanoparticles consisting of superparamagnetic Fe₃O₄ nanoparticles and photoluminescent PbS/CdS quantum dots whose emission lies within the second biological window (II-BW) are developed. The proposed self-assembled Fe₃O₄ and PbS/CdS (II-BW) supernanoparticles [SASNs (II-BW)] exhibit outstanding photoluminescence detectable through a tissue as thick as 14 mm, by overcoming severe light extinction and concomitant autofluorescence in II-BW, and significantly enhanced T₂ relaxivity (282 mM^-1 s^-1, ca. 4 times higher than free Fe₃O₄ nanoparticles) due to largely enhanced magnetic field inhomogeneity. On the other hand, SASNs (II-BW) possess the dual capacity to act as both magnetothermal and photothermal agents, overcoming the main drawbacks of each type of heating separately. When SASNs (II-BW) are exposed to the dual-mode (magnetothermal and photothermal) heating, the thermal energy transfer efficiency is amplified 7-fold compared with magnetic heating alone. These results, in hand with the excellent photo- and colloidal stability, and negligible cytotoxicity, demonstrate the potential use of SASNs (II-BW) for deep-tissue bimodal (magnetic resonance and photoluminescence) in vivo imaging, while simultaneously providing the possibility of SASNs (II-BW)-mediated amplified dual-mode heating treatment for cancer therapy.

Dexmedetomidine enhances ropivacaine-induced sciatic nerve injury in diabetic rats

BACKGROUND

Previous studies suggest that dexmedetomidine has a protective effect against local anaesthetic-induced nerve injury in regional nerve blocks. Whether this potentially protective effect exists in the context of diabetes mellitus is unknown.

METHODS

A diabetic state was established in adult male Sprague-Dawley rats with intraperitoneal injection of streptozotocin. Injections of ropivacaine 0.5%, dexmedetomidine 20 μg kg^-1 (alone and in combination), or normal saline (all in 0.2 ml) were made around the sciatic nerve in control and diabetic rats (n=8 per group). The duration of sensory and motor nerve block and the motor nerve conduction velocity (MNCV) were determined. Sciatic nerves were harvested at post-injection day 7 and assessed with light and electron microscopy or used for pro-inflammatory cytokine measurements.

RESULTS

Ropivacaine and dexmedetomidine alone or in combination did not produce nerve fibre damage in control non-diabetic rats. In diabetic rats, ropivacaine induced significant nerve fibre damage, which was enhanced by dexmedetomidine. This manifested with slowed MNCV, decreased axon density, and decreased ratio of inner to outer diameter of the myelin sheath (G ratio). Demyelination, axon disappearance, and empty vacuoles were also found using electron microscopy. An associated increase in nerve interleukin-1β and tumour necrosis factor-α was also seen.

CONCLUSIONS

Ropivacaine 0.5% causes significant sciatic nerve injury in diabetic rats that is greatly potentiated by high-dose dexmedetomidine. Although the dose of dexmedetomidine used in this study is considerably higher than that used in clinical practice, our data suggest that further studies to assess ropivacaine (alone and in combination with dexmedetomidine) use for peripheral nerve blockade in diabetic patients are warranted.

Efficient Photoelectrochemical Water Oxidation on Hematite with Fluorine-Doped FeOOH and FeNiOOH as Dual Cocatalysts

An effective cocatalyst is usually required to improve the performance of photoelectrochemical (PEC) water splitting catalysts. A fluorine-doped FeOOH (F:FeOOH) cocatalyst on a hematite photoanode was used to lower the onset potential by 140 mV and significantly improve the PEC performance. Moreover, a more effective dual cocatalytic system was prepared by subsequent loading of a FeNiOOH cocatalyst, which resulted in a further decrease of the onset potential by 270 mV. The final onset potential of the Fe₂ O₃ /F:FeOOH/FeNiOOH photoanode was lowered to 0.45 V versus the reversible hydrogen electrode (RHE), which is one of the lowest onset potential values ever reported for hematite photoanodes. The photocurrent also dramatically increased by a factor of approximately 3 to 0.9 mA cm^-2 at 1.0 V versus RHE. Based on the structural, chemical, and electrochemical impedance spectroscopy characterization, the enhanced performance was attributed to the F:FeOOH overlayer, which reduced the surface recombination and accelerated the oxygen evolution reaction activity, and the FeNiOOH cocatalyst, which further enhanced the reaction kinetics. The facile preparation of the F:FeOOH cocatalyst and the design of the dual cocatalytic system will allow the development of high-performance hematite photoanodes.

Plasmonic Au-Loaded Hierarchical Hollow Porous TiO2 Spheres: Synergistic Catalysts for Nitroaromatic Reduction

Plasmonic Au nanoparticle (NP)-loaded hierarchical hollow porous TiO₂ spheres are designed and synthesized with the purpose of enhancing the overall catalytic activity by introducing the Au plasmonic effect into the system, where Au NPs themselves are catalytically active. The constructed nanohybrid exhibits both high activity in 4-nitrophenol reduction, compared to all of the previously reported Au-based catalysts, and high selectivity. The synergy of the inherent catalytic property of Au NPs and the plasmonic effect (mainly via hot electron transfer) under irradiation is confirmed by a series of control experiments. The specifically designed, porous hollow structure also greatly contributes to the good catalytic activity because it provides a large surface area, facilitates reactant adsorption, and hinders charge recombination. In addition, theoretical calculations reveal that such a structure also leads to an increase in light absorption of about 21% in the range of 400-800 nm with respect to a uniform water-TiO₂ background featuring the same filling factor. This work provides insight into the rational design of plasmon-enhanced catalysts that will show their versatility in various electro-/photocatalysis.

Optoelectronic Properties in Near-Infrared Colloidal Heterostructured Pyramidal "Giant" Core/Shell Quantum Dots

Colloidal heterostructured quantum dots (QDs) are promising candidates for next-generation optoelectronic devices. In particular, "giant" core/shell QDs (g-QDs) can be engineered to exhibit outstanding optical properties and high chemical/photostability for the fabrication of high-performance optoelectronic devices. Here, the synthesis of heterostructured CuInSe x S2-x (CISeS)/CdSeS/CdS g-QDs with pyramidal shape by using a facile two-step method is reported. The CdSeS/CdS shell is demonstrated to have a pure zinc blend phase other than typical wurtzite phase. The as-obtained heterostructured g-QDs exhibit near-infrared photoluminescence (PL) emission (≈830 nm) and very long PL lifetime (in the microsecond range). The pyramidal g-QDs exhibit a quasi-type II band structure with spatial separation of electron-hole wave function, suggesting an efficient exciton extraction and transport, which is consistent with theoretical calculations. These heterostructured g-QDs are used as light harvesters to fabricate a photoelectrochemical cell, exhibiting a saturated photocurrent density as high as ≈5.5 mA cm-2 and good stability under 1 sun illumination (AM 1.5 G, 100 mW cm-2). These results are an important step toward using heterostructured pyramidal g-QDs for prospective applications in solar technologies.

Preoperative vitamin D deficiency increases the risk of postoperative cognitive dysfunction: a predefined exploratory sub-analysis

BACKGROUND

Vitamin D is important for maintaining physiological functions including cognition and its deficiency is associated with the occurrence of cognitive impairment. This study was to explore the association between preoperative vitamin D status and the occurrence of postoperative cognitive dysfunction (POCD) in elderly patients undergoing major surgery.

METHODS

This was a predefined exploratory sub-analysis of one-centre data from a randomized controlled trial. In all, 123 elderly (≥ 65 years) patients who were scheduled to undergo major cancer surgery were recruited. Serum 25-hydroxyvitamin D concentration was measured before surgery. In total, 59 nonsurgical control subjects with comparable age and education level were also enrolled. A battery of neuropsychological tests was administered the day before and the 7th day after surgery in patients or at the same time interval in control subjects. POCD was diagnosed according to the ISPOCD1 definition.

RESULTS

71.5% (88/123) of elderly patients had vitamin D deficiency (serum 25-hydroxyvitamin D concentration < 12 ng/ml) before surgery; 24.4% (30/123) of them developed cognitive dysfunction at 1 week after surgery. After adjusting for confounding factors, high preoperative serum 25-hydroxyvitamine D concentration was related to a decreased risk of POCD (odds ratio [OR]: 0.829, 95% confidence interval [CI]: 0.708-0.971; P = 0.020), whereas preoperative vitamin D deficiency was associated with an increased risk of POCD (OR: 8.427, 95% CI: 1.595-44.511; P = 0.012).

CONCLUSIONS

Vitamin D deficiency is prevalent in elderly patients undergoing major cancer surgery and increases the risk of early POCD development. Whether prophylactic vitamin D supplementation can reduce POCD in the elderly deserves further study.

Antioxidant effect of glutathione on promoting 2-keto-l-gulonic acid production in vitamin C fermentation system

AIMS

Oxidative stress limited the growth of cells and 2-keto-l-gulonic acid (2-KGA) production in vitamin C (Vc) fermentation system. The study aims to investigate the antioxidant effect of glutathione on promoting 2-KGA in Vc fermentation system using Ketogulonicigenium vulgare 25B-1 and Bacillus endophyticus ST-1 as the co-culturing microbes.

METHODS AND RESULTS

The activities of antioxidant-related enzymes and qPCR were used to study the antioxidant effect of glutathione addition in Vc fermentation system. The addition of GSH and GSH/GSSG increased 2-KGA production and decreased fermentation time, and the highest 2-KGA production increased by 40·63% and the lowest fermentation time shortened to 60 h when the addition of optimal concentration ratio of GSH/GSSG was 50 : 1. Moreover, the increased production of 2-KGA was accompanied by up-regulated the activities of total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), catalase (CAT) and over-expressed oxidative stress-related genes sod, gst, gr, zwf, gp, which resulted in scavenging reactive oxygen species to reduce oxidative stress in Vc fermentation system.

CONCLUSIONS

Glutathione showed a significant effect on increasing 2-KGA production and decreasing fermentation time in Vc fermentation system. GSH/GSSG could maintain a dynamic balance with two forms of glutathione and the optimal concentration ratio of GSH/GSSG was 50 : 1.

SIGNIFICANCE AND IMPACT OF THE STUDY

Glutathione is proved to be effective to relieve oxidative stress. The promotion effects of GSSG and GSH on 2-KGA production could help to further explore the optimization of co-culture fermentation process for Vc industrial production.

Copy Number Variations with Isolated Fetal Ventriculomegaly

BACKGROUND

Copy Number Variations (CNVs) are an important genetic cause of a number of neurodevelopmental disorders (NDs). However, the association between CNVs and the development and prognosis of fetal isolated mild ventriculomegaly (IMV) is unclear.

OBJECTIVES

To investigate possible associations between CNVs and the development of fetal IMV.

METHODS

This retrospective study recruited 154 subjects with ultrasound-confirmed fetal IMV and 190 subjects in a control cohort who underwent a high-risk prenatal serum screening program. The exclusion criteria included fetus G-banding chromosomal abnormality or positive fetus TORCH infection. DNA samples from all 344 fetuses were examined by an SNP-array. Developmental outcomes were assessed during postnatal follow-up.

RESULTS

Fourteen pathogenic CNVs (pCNVs) were identified in 13 out of 154 IMV fetuses. Three pCNVs were found in 3 out of 190 subjects in the prenatal screening high-risk cohort, with a significant difference (P value=0.016, X2 test). Notably, the 14 pCNVs detected in the IMV cohort were all associated with neurodevelopmental disorders (NDs), including autism, intellectual disability. Among the 13 IMV fetuses carrying pCNVs, five subjects were found in the postnatal follow-up to manifest NDs, including two with autism and three with mild neurodevelopmental delay. The other 8 subjects consisted of three normal infants younger than 12-months old, two lost in the follow-up, and three with the termination of pregnancy. Out of 141 IMV subjects without detectable pCNVs, 123 subjects showed normal development, 16 were lost in the follow-up, 2 subjects terminated the pregnancy due to fetal hydrocephalus or congenital heart disease in the late fetus development.

CONCLUSIONS

This study suggests an association between pCNVs and fetal IMV. pCNVs may be involved in the pathological process of fetal IMV and postnatal NDs. Identifying specific genomic alterations may provide an insight into pathogenetic mechanism and aid better diagnosis and prognosis of neurodevelopmental outcomes in fetal IMV.

[Analysis of Arsenic Compounds in Blood and Urine by HPLC-ICP-MS]

OBJECTIVES

To establish an analysis method for the detection of 6 arsenic compounds [AsC, AsB, As（Ⅲ）, DMA, MMA and As（V）] in blood and urine by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry （HPLC-ICP-MS）, and apply it to real cases.

METHODS

Triton was used to damage cells, and then EDTA·2Na·2H2O was used to complex arsenic compounds in cells, and sonication and protein deposition by acetonitrile were performed for sample pretreatment. With the mobile phase consisted of ammonium carbonate and ultrapure water, gradient elution was performed for obtaining the arsenic compounds in samples, which were analysed by ICP-MS with Hamilton PRP-X100 column.

RESULTS

The limits of detection in blood were 1.66-10 ng/mL, while the lower limits of quantitation in blood ranged from 5 to 30 ng/mL. The limits of detection in urine were 0.5-10 ng/mL, while the lower limits of quantitation in urine were 5-30 ng/mL. The relative standard deviation of inter-day and intra-day precisions was less than 10%. This method had been successfully applied to 3 cases.

CONCLUSIONS

This study has established an analysis method for detecting 6 common arsenic compounds in blood and urine, which can be used to detect the arsenic compounds in the blood and urine from arsenic poisoning cases as well as the patients under arsenic treatment.

Toward Enhancing Solar Cell Performance: An Effective and "Green" Additive

Performance of bulk heterojunction polymer solar cells (PSCs) highly relies on the morphology of the photoactive layer involving conjugated polymers and fullerene derivatives as donors and acceptors, respectively. Herein, butylamine was found to be able to optimize the morphology of the donor/acceptor (D/A) film composed of a blend of poly(3-hexylthiophene-2,5-diyl) (P3HT) and phenyl-C₆₁-butyric acid methyl ester (PCBM). Compared to the commonly used alkane dithiols and halogenated additives with high boiling points, butylamine has a much lower boiling point between 77 and 79 °C, and it is also much "greener". A specific interaction between butylamine and PCBM was demonstrated to account for the morphology improvement. Essentially, butylamine can selectively dissolve PCBM in the P3HT:PCBM blend and facilitate the diffusion of PCBM in the film fabrication processes. Atomic force microscopy and X-ray photoelectron spectroscopy investigations confirmed the formation of the P3HT-enriched top surface and the abundance of PCBM at the bottom side, i.e., the formation of vertical phase segregation, as a consequence of the specific PCBM-butylamine interaction. The D/A film with inhomogeneously distributed D and A components in the vertical film direction, with more P3HT at the hole extraction side and more PCBM at the electron extraction side, enables more efficient charge extraction in the D/A film, reflected by the largely enhanced fill factor. The power conversion efficiency of devices reached 4.03 and 4.61%, respectively, depending on the thickness of the D/A film, and these are among the best values reported for P3HT:PCBM-based devices. As compared to the devices fabricated without the introduction of butylamine under otherwise the same processing conditions, they represented 19.6 and 21.6% improvement in the efficiency, respectively. The discovery of butylamine as a new, effective additive in enhancing the performance of PSCs strongly suggests that the differential affinity of additives toward donors and acceptors likely plays a more important role in morphology optimization than their boiling point, different from what was reported previously. The finding provides useful information for realizing large-area PSC fabrication, where a "greener" additive is always preferred.

CdS nanoparticles of different lengths induce differential responses in some of the liver functions of mice

Cadmium sulfide nanoparticles (CdS NPs) are one of important nanoparticle materials which are widely used in photoelectric production, but their potential health hazard to the liver is not clear. This study is aimed at exploring the possible mechanisms of liver injury induced by CdS NPs. Male mice were treated with nanoparticles of 110-130 nm and 80-100 nm cadmium sulfide. The main methods were based on detecting the vigor of superoxide dismutase (SOD) and glutathione (GSH), and content of malondialdehyde (MDA) in both blood and liver tissues as well as on observing the pathological changes in liver tissue. CdS NPs suppressed the activity of SOD and GSH, and increased the serum MDA content (p < 0.05); both effects were observed together in liver tissues of 80-100 nm group (p < 0.05) and were accompanied by an obviously inflammatory response. CdS NPs induced oxidative damage and inflammatory response in liver tissue, which may be an underlying mechanism for its pulmonary toxicity. Additionally, the toxicity of CdS NPs was closely related to the size of nanoparticles. Pathological results showed that the hepatotoxicity of shorter CdS NPs is greater than that of longer CdS NPs (Tab. 6, Fig. 3, Ref. 20).

Abstract P2-06-03: Clinicopathologic characteristics and genomic essence analyses revealed estrogen receptor positive, progesterone receptor negative and human epidermal growth factor receptor 2 negative breast cancer to be more basal-like and endocrine resistant

Background: Estrogen receptor positive/ progesterone receptor negative/ human epidermal growth factor receptor 2 negative (ER+/PR-/HER2-) tumors define a distinct subtype of ER+ breast cancer, characterized by poor response to endocrine therapy and poor prognosis. The genomic landscape of ER+/PR-/HER2- tumor has yet to be systematically studied,and driver events for tumor progression and endocrine resistance with loss of PR expression are yet to be identified. Methods: We assessed 13,410 ER+/PR-/HER2- patients from Surveillance, Epidemiology, and End Results (SEER), the Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) for clinicopathologic characteristics, survival and genomic analyses. Patients were divided into endocrine-resistant and endocrine-sensitive groups using an endocrine therapy sensitivity score [(0.8*ER+1.2*PGR+BCL2+SCUBE2)/4], and we further explored genomic events enriched in the endocrine-resistant group. Results: Clinicopathologic features and survival outcomes of ER+/PR-/HER2- patients were worse than ER+/PR+/HER2- in SEER and METABRIC cohort. The genomic landscape of ER+/PR-/HER2- tumors revealed them to have more aggressive properties, like a higher percentage of luminal B (29-35%) and basal-like (4-16%) subtypes; more intClust subtypes with high genomic instability (intClust1, 6); more TP53 mutation and less PIK3CA mutation; and more copy number variation events. ER+/PR-/HER2- tumors have more focal amplification events, including 8p11.23 (ZNF703) and 17q23.1 (RPS6KB1) and more focal deletion events, such as 17q21.31 (BRCA1) and 14q24.3 (MLH3). Pathifier pathway analyses showed that up-regulated pathways in ER+/PR-/HER2-tumors included those associated with biosynthesis, metabolism, drug resistance and DNA replications (FDR&lt;0.1). Endocrine sensitivity score for ER+/PR-/HER2- group was significantly lower than ER+/PR+/HER2- group. When split by 1st quartile of endocrine sensitivity score, up to 72.7% of ER+/PR-/HER2- tumors were grouped into the endocrine-resistant group. Mutant-allele tumor heterogeneity (MATH) score is significantly lower in the endocrine-resistant group. Several focal SCNA events were more common in the endocrine-resistant group (P&lt;0.05), including 8q24.21 amplification with only the MYC gene in the “peak” region. Pathways unregulated in the endocrine-resistant group of ER+/PR-/HER2- tumor included MYC pathway and mTORC1 signaling (FDR&lt;0.25). Conclusion: ER+/PR-/HER2- breast cancer was a heterogeneous tumor group and featured more basal-like and luminal B characteristics. The ER+/PR-/HER2- tumors are relatively resistant to endocrine therapy, and MYC pathway enrichment and corresponding 8q24.21 amplification might be one of the drug-resistance mechanisms. Our study provides an overall understanding of the distinct genomic landscape of ER+/PR-/HER2- breast cancer. Further investigations into the pathways activated with the loss of PR expression may provide clues for novel changes in the therapeutic regimens of ER+/PR-/HER2- breast cancer.

Citation Format: Liu X, Ma D, Jiang Y-Z, Liu Y-R, Yu K-D, Shao Z-M. Clinicopathologic characteristics and genomic essence analyses revealed estrogen receptor positive, progesterone receptor negative and human epidermal growth factor receptor 2 negative breast cancer to be more basal-like and endocrine resistant [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-06-03.

Towards understanding the unusual photoluminescence intensity variation of ultrasmall colloidal PbS quantum dots with the formation of a thin CdS shell

In this study, we report anomalous size-dependent photoluminescence (PL) intensity variation of PbS quantum dots (QDs) with the formation of a thin CdS shell via a microwave-assisted cation exchange approach. Thin shell formation has been established as an effective strategy for increasing the PL of QDs. Nonetheless, herein we observed an unusual PL decrease in ultrasmall QDs upon shell formation. We attempted to understand this abnormal phenomenon from the perspective of trap density variation and the probability of electrons and holes reaching surface defects. To this end, the quantum yield (QY) and PL lifetime (on the ns-μs time scales) of pristine PbS QDs and PbS/CdS core/shell QDs were measured and the radiative and non-radiative recombination rates were derived and compared. Moreover, transient absorption (TA) analysis (on the fs-ns time scale) was performed to better understand exciton dynamics at early times that lead to and affect longer time dynamics and optical properties such as PL. These experimental results, in conjunction with theoretical calculations of electron and hole wave functions, provide a complete picture of the photophysics governing the core/shell system. A model was proposed to explain the size-dependent optical and dynamic properties observed.

Harnessing the properties of colloidal quantum dots in luminescent solar concentrators

This review summarizes the recent progress, challenges and perspectives of luminescent solar concentrators based on colloidal quantum dots via harnessing their properties.