Development of a haematological indices-based nomogram for prognostic prediction and immunotherapy response assessment in primary pulmonary lymphoepithelioma-like carcinoma patients.

Background: Primary pulmonary lymphoepithelioma-like carcinoma (PPLELC) is a rare yet aggressive malignancy. This study aims to investigate a deep learning model based on hematological indices, referred to as haematological indices-based signature (HIBS), and propose multivariable predictive models for accurate prognosis prediction and assessment of therapeutic response to immunotherapy in PPLELC. Methods: This retrospective study included 117 patients with PPLELC who received immunotherapy and were randomly divided into a training (n=82) and a validation (n=35) cohort. A total of 41 hematological features were extracted from routine laboratory tests and the least absolute shrinkage and selection operator (LASSO) algorithm were utilized to establish the HIBS. Additionally, we developed a nomogram using the HIBS and clinical characteristics through multivariate Cox regression analysis. To evaluate the nomogram's predictive performance, we used calibration curves and calculated the time-dependent area under the curve (AUC). Kaplan-Meier survival analysis was performed to estimate progression-free survival (PFS) in both cohorts. Results: The proposed HIBS comprised 14 hematological features and showed that patients who experienced disease progression had significantly higher HIBS scores compared to those who did not progress (P<0.001). Five prognostic factors, including HIBS, tumor-node-metastasis (TNM) stage, presence of bone metastasis and the specific immunotherapy regimen, were found to be independent factors and were used to construct a nomogram, which effectively categorized PPLELC patients into a high-risk and a low-risk group, with patients in the high-risk patients demonstrating worse PFS (7.0 vs. 18.0 months, P<0.001) and lower overall response rates (22.2% vs. 52.7%, P<0.001). The nomogram showed satisfactory discrimination for PFS, with AUC values of 0.837 and 0.855 in the training and validation cohorts, respectively. Conclusions: The HIBS-based nomogram could effectively predict the PFS and response of patients with PPLELC regarding immunotherapy and serve as a valuable tool for clinical decision making.

Nitrogen dynamics of alpine swamp meadows are less responsive to climate warming than that of alpine meadows.

The freeze-thaw cycle mediates permafrost soil hydrothermal status, nitrogen (N) mineralization, and loss. Furthermore, it affects root development and competition among nitrophilic and other species, shaping the pattern of N distribution in alpine ecosystems. However, the specific N dynamics during the growing season and N loss during the non-growing season in response to climate warming under low- and high-moisture conditions are not well documented. Therefore, we added 15N tracers to trace the fate of N in warmed and ambient alpine meadows and alpine swamp meadows in the permafrost region of the Qinghai-Tibet Plateau. During the growing season, warming increased 15N recovery (15Nrec) in shoots of K. humilis, litters, 0-5 and 5-20 cm roots in the alpine meadow by 149.94 % ± 52.87 %, 114.58 % ± 24.43 %, 61.11 % ± 32.27 %, and 97.12 % ± 42.92 %, respectively, while increased 15Nrec of litters by 151.55 % ± 27.06 % in the alpine swamp meadow. During the non-growing season, warming reduced 15N stored in roots by 486.77 % ± 57.90 %, though increased the 15N recovery in 5-20 cm soil depth by 76.68 % ± 39.42 % in the alpine meadow, whereas it did not affect N loss during the non-growing season in the alpine swamp meadow. Overall, warming promoted N utilization by increasing the plant N pool during the growing season, and enhanced root N loss and downward migration during the non-growing season due to the freeze-thaw process, which may result in fine root turnover and cell destruction releasing N in the alpine meadow. Conversely, the N dynamics of alpine swamp meadows were less responsive to climate warming.

The seasonal variability of future evapotranspiration over China during the 21st century.

The evapotranspiration (ET) plays a crucial role in shaping regional climate patterns and serves as a vital indicator of ecosystem function. However, there remains a limited understanding of the seasonal variability of future ET over China and its correlation with environmental drivers. This study evaluated the skills of 27 models from the Six Phase of Coupled Model Intercomparison Project in modeling ET and the Bayesian Model Averaging (BMA) method was employed to merge monthly simulated ET based on the top five best-performing models. The seasonal changes in ET under three climate scenarios from 2030 to 2099 were analyzed based on the BMA-merged ET, which was well validated with observed ET collected from fourteen flux sites across China. Significant increasing ET over China are projected under all seasons during 2030-2099, with 0.05-0.13 mm yr-1, 0.11-0.23 mm yr-1, and 0.20-0.41 mm yr-1 under SSP1-2.6, SSP2-4.5 and SSP5-8.5 scenarios, respectively. Relative to the historical period (1980-2014), the relative increase in ET over China is highest in winter and lowest in summer. Seasonal ET increases significantly in all seven climate sub-regions under high forcing scenario. Higher ET increase is generally found in southeastern humid regions, while lowest ET increase occurs in northwest China. At the country level, the primary factor driving ET increase during spring, summer, and autumn seasons is the increasing net radiation and warming. In contrast, ET increase during winter is influenced not only by energy factors but also by vegetation-related factors. Future seasonal ET increase is predominantly driven by increasing energy factors in the southeastern humid region and Tibetan Plateau, while seasonal ET changes in the northwest region prevailingly depend on soil moisture. Results indicate that China will experience a "wet season will get wetter, and dry season will become drier" in the 21st century with high radiation forcing scenario.

A Clinical Tool to Predict the Microvascular Invasion Risk in Patients with Hepatocellular Carcinoma.

BACKGROUND: Microvascular invasion (MVI) plays an important role in tumor progression. The aim of this study is to establish and validate an effective hematological nomogram for MVI prediction in hepatocellular carcinoma (HCC). METHODS: A retrospective study was performed in a primary cohort that includes 1306 patients clinicopathologically diagnosed with HCC, and a validation cohort contained 563 continuous patients. Univariate logistic regression was used to assess the association between variables included both clinicopathologic factors and coagulation parameters (prothrombin time, activated partial thromboplastin time, fibrinogen, and thrombin time [TT]) and MVI. Multiple logistic regression was used to construct a prediction nomogram. We tested the accuracy of the nomogram by discrimination and calibration, and then plotted decision curves to assess the benefits of the nomogram-assisted decisions in a clinical context. RESULTS: In the two cohorts, patients without MVI had the longest overall survival (OS), compared the OS with MVI. The multivariate analysis indicated that age, sex, tumor node metastasis (TNM) stage, aspartate aminotransferase, alpha fetoprotein, C-reactive protein, and TT were identified as significant independent predictors of MVI of HCC patients. The Hosmer-Lemeshow test showed good point estimate associated P value between predicted risk and observed risk across the deciles. Moreover, the calibration performance of the nomogram risk scores in each decile of the primary cohort was within 5 percentage points of the mean predicted risk score, and in the validation cohort, the observed risk in 90% decile was within 5 percentage points of the mean predicted risk score. CONCLUSIONS: A noninvasive and easy-to-use nomogram was established and may be used to predict preoperative MVI in HCC.

Prognostic effect of CD73 in pancreatic ductal adenocarcinoma for disease-free survival after radical surgery.

PURPOSE: Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease with a high potency of metastasis or recurrence after radical resection. Effective predictors for metastasis and recurrence postoperatively were dominant for the development of systemic adjuvant treatment regimens. The ATP hydrolase correlated gene CD73 was described as a promoter in tumor growth and immune escape of PDAC. However, there lacked research focused on the role of CD73 in PDAC metastasis. This study aimed to investigate the expression of CD73 in PDAC patients with different outcomes as well as the prognostic effect of CD73 for disease-free survival (DFS). METHODS: The expression level of CD73 in cancerous samples from 301 PDAC patients was evaluated by immunohistochemistry (IHC) and translated into a histochemistry score (H-score) by the HALO analysis system. Then, the CD73 H-score was involved in multivariate Cox regression along with other clinicopathological characteristics to find independent prognostic factors for DFS. Finally, a nomogram was constructed based on those independent prognostic factors for DFS prediction. RESULTS: Higher CD73 expression was found in PDAC patients with tumor metastasis postoperatively. Meanwhile, higher CD73 expressions were also investigated in PDAC patients diagnosed with advanced N stage and T stage. Furthermore, CD73 H-score along with tumor margin status, CA19-9, 8th N stage, and adjuvant chemotherapy was indicated as independent prognostic factors for DFS in PDAC patients. The nomogram based on these factors predicted DFS in a good manner. CONCLUSION: CD73 was associated with PDAC metastasis and served as an effective prognostic factor for DFS in PDAC patients after radical surgery.

Significance of Dynamic Changes of VCA-IgA Levels in Pre- and Post-treatment Plasma of Patients with Nasopharyngeal Carcinoma: Development of a Clinically-Oriented Model.

INTRODUCTION: Nasopharyngeal carcinoma (NPC) responds well to radiotherapy but recurrence and metastasis are common. Currently, there is no widely used biomarker for accurately predicting the recurrence and metastasis of NPC. In this study, we aimed to evaluate the prognostic ability of Epstein-Barr virus (EBV) capsid antigen (VCA-IgA) kinetics by assessing the dynamic changes of VCA-IgA levels in the pre- and post-treatment plasma of patients with NPC and have proposed a prognostic model for clinical use. METHODS: The clinical records of patients with NPC diagnosed at Sun Yat-sen University Cancer Center were retrieved and classified into a respondent (n = 83) or non-respondent (n = 25) cohort based on their response to antitumor therapy. Factors associated with the outcomes of the patients were assessed and incorporated in a nomogram. For internal validation, bootstrapping with 1000 resamples was used. The prediction accuracy and discriminative ability of the nomogram were investigated by calibration and concordance index (C-index) and plotted decision curves to assess the benefits of nomogram-assisted decisions in a clinical context. RESULTS: Plasma VCA-IgA level of the non-respondent cohort at the 6th month after treatment was found significantly higher than the respondent cohort. Post-treatment VCA-IgA level, smoking, and distant metastases were identified as independent risk factors for disease-free survival (DFS), and were used to stratify patients with NPC into three risk groups. The median DFS of the low-, middle- and high-risk groups were 48.5, 35.0, and 15.5 months, respectively. The C-index of the nomogram was 0.848 (95% CI 0.769-0.926), demonstrating good clinical accuracy for predicting the DFS of patients with NPC. The decision curve showed that the nomogram in predicting DFS was better than VCA-IgA level, smoking, and distant metastases. CONCLUSION: The proposed VCA-IgA-based nomogram demonstrated a promising ability to predict the DFS of patients with NPC after antitumor therapy. It could be used as a clinical guidance to improve the therapeutic/surveillance strategies of these patients.

Recurrence risk stratification based on Epstein-Barr virus DNA to identify enlarged retropharyngeal lymph nodes of nasopharyngeal carcinoma: A model-histopathologic correlation study.

Background: Accurate assessment of the nature of enlarged retropharyngeal lymph nodes (RLN) of nasopharyngeal carcinoma (NPC) patients after radiotherapy is related to selecting appropriate treatments and avoiding unnecessary therapy. This study aimed to develop a non-invasive and effective model for predicting the recurrence of RLN (RRLN) in NPC. Materials and methods: The data of post-radiotherapy NPC patients (N = 76) with abnormal enlargement of RLN who underwent endonasopharyngeal ultrasound-guided fine-needle aspirations (EPUS-FNA) were examined. They were randomly divided into a discovery (n = 53) and validation (n = 23) cohort. Univariate logistic regression was used to assess the association between variables (magnetic resonance imaging characteristics, EBV DNA) and RRLN. Multiple logistic regression was used to construct a prediction model. The accuracy of the model was assessed by discrimination and calibration, and decision curves were used to assess the clinical reliability of the model for the identification of high risk RLNs for possible recurrence. Results: Abnormal enhancement, minimum axis diameter (MAD) and EBV-DNA were identified as independent risk factors for RRLN and could stratify NPC patients into three risk groups. The probability of RRLN in the low-, medium-, and high-risk groups were 37.5, 82.4, and 100%, respectively. The AUC of the final predictive model was 0.882 (95% CI: 0.782-0.982) in the discovery cohort and 0.926 (95% CI, 0.827-1.000) in the validation cohort, demonstrating good clinical accuracy for predicting the RRLN of NPC patients. The favorable performance of the model was confirmed by the calibration plot and decision curve analysis. Conclusion: The nomogram model constructed in the study could be reliable in predicting the risk of RRLN after radiotherapy for NPC patients.

Experimental Study on Dynamic Compressive Behaviors of Sand under Passive Confining Pressure.

Dynamic compressive tests of sand under passive confining pressure were carried out using a Split Hopkinson Pressure Bar (SHPB) setup. The dynamic response, energy dissipation and particle-breaking behaviors of sand subjected to high-speed impact were investigated. Sand specimens with moisture contents of 0%, 2%, 4%, 8%, 10% and 12% and relative densities of 0.1, 0.5 and 0.9 were prepared. The variation in the strain rate was controlled between 90 s-1 and 500 s-1. The specimens were confined in a designed sleeve to create passive confining pressure. The experimental results show that the sand specimens were extremely sensitive to the strain rate. When the strain rate was less than 400 s-1, the stress and strain of the specimens increased with the increase in the strain rate but decreased when the strain rate exceeded 400 s-1. The peak strain and peak stress increased with the increase in the relative density. Particle breakage was aggravated with the strain-rate increase. Compared with the specimen without water, the relative breakage rate of the specimen with a moisture content of 12% decreased by 30.53% when the strain rate was about 95 s-1 and by 25.44% when the strain rate was about 460 s-1. The analysis of energy dissipation revealed the essential cause of sand destruction. The specific energy absorption rate increased with the increases in the initial relative density and moisture content.

Dual coupled effects of low concentration gold nanorods on energy transfer and luminescence enhancement in Eu/Tb co-doped films.

Eu/Tb co-doped films with low concentration gold nanorods have been prepared using the solution process. The luminescence spectra investigations indicate that the introduction of nanorods can effectively enhance the energy transfer from Tb to Eu under excitation of 292 nm, because of the plasmonic coupling with excited Tb complex. Under excitation of 360 nm, the emission at 612 nm is enhanced, the enhancement factor increases and then decreases as the molar ratio of Tb and Eu increases. The luminescence enhancement is attributed to the metal enhanced luminescence resulting from plasmonic coupling with excited Eu complex. The dual effects of LSPR on energy transfer and emission enhancement are both observed. More details on the luminescence of Eu/Tb co-doped films with nanorods are demonstrated, which gain a deeper understanding of the interactions luminescent-particle and luminescent-luminescent.

The Survival Advantage of Females at Premenopausal Age Is Race Dependent in Colorectal Cancer.

BACKGROUND: A female prognostic advantage in younger individuals has been demonstrated in various cancers. Several large-scale analyses based on different racial backgrounds have reported inconsistent results in colorectal cancer. The aim of the present study was to evaluate the prognostic value of sex and age in patients with colorectal cancer of different ethnic groups. METHODS: We identified 71,812 eligible patients from the Surveillance, Epidemiology and End Results database. According to age at diagnosis, the patients were categorized into premenopausal age (≤45 yrs), menopausal age (46-54 yrs), and postmenopausal age (≥55 yrs) subgroups for further analysis. RESULTS: Multivariate analysis identified the female survival advantage to be significant in the premenopausal age subgroup (P = 0.002, HR (95% CI): 0.73 (0.60-0.89)), diminished in the menopausal age subgroup (P = 0.09), and absent in the postmenopausal age subgroup (P = 0.96). Furthermore, the female survival advantage at premenopausal age was significant only in white patients (P = 0.001, HR (95% CI): 0.68 (0.54-0.87)) and not in either American Indian/Alaska Native or Asian or Pacific Islander patients. There was a trend of better survival of females in black patients (P = 0.07). CONCLUSIONS: Sex was a major prognostic factor in colorectal cancer patients, especially premenopausal women, and the difference was also associated with race.

Importance of active layer freeze-thaw cycles on the riverine dissolved carbon export on the Qinghai-Tibet Plateau permafrost region.

The Qinghai-Tibet Plateau (QTP) is experiencing severe permafrost degradation, which can affect the hydrological and biogeochemical processes. Yet how the permafrost change affects riverine carbon export remains uncertain. Here, we investigated the seasonal variations of dissolved inorganic and organic carbon (DIC and DOC) during flow seasons in a watershed located in the central QTP permafrost region. The results showed that riverine DIC concentrations (27.81 ± 9.75 mg L-1) were much higher than DOC concentrations (6.57 ± 2.24 mg L-1). DIC and DOC fluxes were 3.95 and 0.94 g C m-2 year-1, respectively. DIC concentrations increased from initial thaw (May) to freeze period (October), while DOC concentrations remained relatively steady. Daily dissolved carbon concentrations were more closely correlated with baseflow than that with total runoff. Spatially, average DIC and DOC concentrations were positively correlated with vegetation coverage but negatively correlated with bare land coverage. DIC concentrations increased with the thawed and frozen depths due to increased soil interflow, more thaw-released carbon, more groundwater contribution, and possibly more carbonate weathering by soil CO2 formed carbonic acid. The DIC and DOC fluxes increased with thawed depth and decreased with frozen layer thickness. The seasonality of riverine dissolved carbon export was highly dependent on active layer thawing and freezing processes, which highlights the importance of changing permafrost for riverine carbon export. Future warming in the QTP permafrost region may alter the quantity and mechanisms of riverine carbon export.

Randomised phase III trial of concurrent chemoradiotherapy with extended nodal irradiation and erlotinib in patients with inoperable oesophageal squamous cell cancer.

BACKGROUND: This randomised phase III study was conducted to investigate the efficacy of extended nodal irradiation (ENI) and/or erlotinib in inoperable oesophageal squamous cell cancer (ESCC). PATIENTS AND METHODS: Patients with histologically confirmed locally advanced ESCC or medically inoperable disease were randomly assigned (ratio 1:1:1:1) to one of four treatment groups: group A, radiotherapy adoption of ENI with two cycles of concurrent TP chemotherapy (paclitaxel 135 mg/m2 day 1 and cisplatin 20 mg/m2 days 1-3, every 4 weeks) plus erlotinib (150 mg per day during chemoradiotherapy); group B, radiotherapy adoption of ENI with two cycles of concurrent TP; group C, radiotherapy adoption of conventional field irradiation (CFI) with two cycles of concurrent TP plus erlotinib; group D, radiotherapy adoption of CFI with two cycles of concurrent TP. RESULTS: A total of 352 patients (88 assigned to each treatment group) were enrolled. The 2-year overall survival rates of group A, B, C and D were 57.8%, 49.9%, 44.9% and 38.7%, respectively (P = 0.015). Group A significantly improved 2-year overall survival compared with group D. The ENI significantly improved overall survival in patients with inoperable ESCC (P = 0.014). The addition of erlotinib significantly decreased loco-regional recurrence (P = 0.042). Aside from rash and radiation oesophagitis, the incidence of grade 3 or greater toxicities did not differ among 4 groups. CONCLUSION: Chemoradiotherapy with ENI and erlotinib might represent a substantial improvement on the standard of care for inoperable ESCC. ENI alone should be adopted in concurrent chemoradiotherapy for ESCC patients.

Emerging roles of circular RNA hsa_circ_0000064 in the proliferation and metastasis of lung cancer.

Circular RNAs (circRNAs), a novel class of widespread and diverse endogenous RNAs, can regulate gene expression in mammals. CircRNAs have recently been identified as microRNA sponges and involved in the development of some human diseases. However, the role of circRNAs in the process of tumorigenesis and development of lung cancer remains vague. The purpose of this study is to investigate the role of circRNAs in the lung cancer. In this study, we chose hsa_circ_0000064 as a targeted circRNA to investigate its clinical significances in lung cancer patients. The result indicated that hsa_circ_0000064 was up-regulated in lung cancer tissues and lung cancer cell lines (A549 and H1229). Moreover, its aberrant expression was correlated with several clinical characteristics, including T stage, lymphatic metastasis, and TNM stage. Fluorescence in situ hybridization detected that hsa_circ_0000064 was mostly located in the cytoplasm in A549 and H1229 cells. In addition, knockdown of hsa_circ_0000064 with siRNA dramatically attenuated the proliferation, blocked cell cycle progression, and promoted cell apoptosis. Western blot analysis showed that the protein levels of caspase-3, caspase-9, bax, p21, CDK6 and cyclin D1 significantly restrained by si-hsa_circ_0000064, while the expression of bcl-2 notably increased in A549 and H1229 cells. Further, si-hsa_circ_0000064 also abated migration and invasion activities of A549 and H1229 cells, which may be associated with reduced expressions of MMP-2 and MMP-9. In general, our data suggest that hsa_circ_0000064 represents a novel potential biomarker and therapeutic target of lung cancer.

Effects of warming and nitrogen fertilization on GHG flux in an alpine swamp meadow of a permafrost region.

Uncertainties in the seasonal changes of greenhouse gases (GHG) fluxes in wetlands limit our accurate understanding of the responses of permafrost ecosystems to future warming and increased nitrogen (N) deposition. Therefore, in an alpine swamp meadow in the hinterland of the Qinghai-Tibet Plateau, a simulated warming with N fertilization experiment was conducted to investigate the key GHG fluxes (ecosystem respiration [Re], CH4 and N2O) in the early (EG), mid (MG) and late (LG) growing seasons. Results showed that warming (6.2 °C) increased the average seasonal Re by 30.9% and transformed the alpine swamp meadow from a N2O sink to a source, whereas CH4 flux was not significantly affected. N fertilization (4 g N m-2 a-1) alone had no significant effect on the fluxes of GHGs. The interaction of warming and N fertilization increased CH4 uptake by 69.6% and N2O emissions by 26.2% compared with warming, whereas the Re was not significantly affected. During the EG, although the soil temperature sensitivity of the Re was the highest, the effect of warming on the Re was the weakest. The primary driving factor for Re was soil surface temperature, whereas soil moisture controlled CH4 flux, and the N2O flux was primarily affected by rain events. The results indicated: (i) increasing N deposition has both positive and negative feedbacks on GHG fluxes in response to climate warming; (ii) during soil thawing process at active layer, low temperature of deep frozen soils have a negative contribution to Re in alpine ecosystems; and (iii) although these alpine wetland ecosystems are buffers against increased temperature, their feedbacks on climate change cannot be ignored because of the large soil organic carbon pool and high temperature sensitivity of the Re.

Carbon nanotubes dispersed in aqueous solution by ruthenium(ii) polypyridyl complexes.

Cationic ruthenium(ii) polypyridyl complexes with appended pyrene groups have been synthesized and used to disperse single-walled carbon nanotubes (SWCNT) in aqueous solutions. To this end, planar pyrene groups enable association by means of π-stacking onto carbon nanotubes and, in turn, the attachment of the cationic ruthenium complexes. Importantly, the ionic nature of the ruthenium complexes allows the formation of stable dispersions featuring individualized SWCNTs in water as confirmed in a number of spectroscopic and microscopic assays. In addition, steady-state photoluminescence spectroscopy was used to probe the excited state interactions between the ruthenium complexes and SWCNTs. These studies show that the photoluminescence of both, that is, of the ruthenium complexes and of SWCNTs, are quenched when they interact with each other. Pump-probe transient absorption experiments were performed to shed light onto the nature of the photoluminescence quenching, showing carbon nanotube-based bands with picosecond lifetimes, but no new bands which could be unambigously assigned to photoinduced charge transfer process. Thus, from the spectroscopic data, we conclude that quenching of the photoluminescence of the ruthenium complexes is due to energy transfer to proximal SWCNTs.

Luminescent Polymer Composite Films Containing Coal-Derived Graphene Quantum Dots.

Luminescent polymer composite materials, based on poly(vinyl alcohol) (PVA), as a matrix polymer and graphene quantum dots (GQDs) derived from coal, were prepared by casting from aqueous solutions. The coal-derived GQDs impart fluorescent properties to the polymer matrix, and the fabricated composite films exhibit solid state fluorescence. Optical, thermal, and fluorescent properties of the PVA/GQD nanocomposites have been studied. High optical transparency of the composite films (78 to 91%) and excellent dispersion of the nanoparticles are observed at GQD concentrations from 1 to 5 wt %. The maximum intensity of materials photoluminescence has been achieved at 10 wt % GQD content. These materials could be used in light emitting diodes (LEDs), flexible electronic displays, and other optoelectronic applications.

Luminogenic iridium azide complexes.

The synthesis and characterization of luminogenic, bioorthogonal iridium probes is described. These probes exhibit long photoluminescence lifetimes amenable to time-resolved applications. A simple, modular synthesis via 5-azidophenanthroline allows structural variation and allows optimization of cell labeling.

Bandgap engineering of coal-derived graphene quantum dots.

Bandgaps of photoluminescent graphene quantum dots (GQDs) synthesized from anthracite have been engineered by controlling the size of GQDs in two ways: either chemical oxidative treatment and separation by cross-flow ultrafiltration, or by a facile one-step chemical synthesis using successively higher temperatures to render smaller GQDs. Using these methods, GQDs were synthesized with tailored sizes and bandgaps. The GQDs emit light from blue-green (2.9 eV) to orange-red (2.05 eV), depending on size, functionalities and defects. These findings provide a deeper insight into the nature of coal-derived GQDs and demonstrate a scalable method for production of GQDs with the desired bandgaps.

Ascertaining free histidine from mixtures with histidine-containing proteins using time-resolved photoluminescence spectroscopy.

The use of photoluminescent probes for differentiating free amino acids from biomolecules containing the same amino acids is challenging. Photoluminescent probes generally present similar emission spectra when in the presence of either free-amino acids or protein containing those same amino acids. Probes based on cyclometalated iridium(III) complexes Ir(L)2(sol)2 (where L is 2-phenylpyridine, 2-(2,4-difluorophenyl)pyridine, or benzo[h]quinolone, and sol is a solvent molecule) present long-lived emission when bound to histidine. This emission is tuned by the microenvironment around the complex and therefore its lifetime is different for free histidine (487 ns) than from histidine-containing proteins such as bovine serum albumin (average lifetime > 700 ns). As a proof-of-concept we demonstrate that free histidine can be discerned from a mixture with histidine-containing proteins by using time-resolved photoluminescence decays. In the presence of multiple sources of histidine, iridium(III) probes display a multiexponential decay, which can be fitted by nonlinear least-squares methods to separate the different components. Because the pre-exponential factor of the 487 ns lifetime is proportional to the concentration of free histidine, we can use it to assess the amount of free histidine in solution even in the presence of proteins such as bovine serum albumin. We also show that iridium(III) probes displaying different photoluminescence maxima can be produced by modifying the ancillary ligands of the metal complex.