Search

In this study, we have undertaken the development of two fluorescent sensors based on calixarene compounds for the purpose of detecting cesium in water. By introducing the sulfonate functional groups, we have considerably improved the water solubility of sensors, enabling complete dissolution of products in aqueous media and direct analysis of polluted water samples. Through rigorous experiments, we have demonstrated that the complexation of Cs+ ions with sensors 1 and 2 in water leads to a remarkable enhancement of fluorescence. This fluorescence enhancement serves as a reliable indication of cesium presence and allows for sensitive detection. To further advance the practical application of our sensors, we have successfully integrated calixarene sensors 1 and 2 into a microfluidic sensor chip. This integration has enabled real-time, on-line measurements and has resulted in the development of a portable detection device capable of detecting cesium ions in water samples at parts per billion (ppb) levels. This device holds great promise for environmental monitoring and assessment, providing a convenient and efficient solution for cesium detection. Our work represents a significant advancement in the field of cesium detection, displaying the efficacy of calixarene-based fluorescent sensors and their integration into microfluidic systems. The enhanced water solubility, fluorescence response, and portability of our detection device offers tremendous potential for applications in environmental monitoring, water quality assessment, and emergency response scenarios where rapid and accurate cesium detection is crucial. [ABSTRACT FROM AUTHOR]

A new class of photoswitches and the corresponding elementary photoinduced reaction, the so-called Excited-State Cation Transfer (ESCT), are investigated. This reaction relies on an intramolecular photo-release/photo-complexation of cation: after irradiation, the cation is translocated from a complexation site 1 to a site 2 during the excited state lifetime. Our purpose is thus to develop a computational strategy based on Density Functional theory (DFT) and its time-dependent counterpart (TD-DFT) to improve the different properties of the ESCT photoswitches, namely (i) the ground state complexation constant K , (ii) the excited state complexation constant K *, (iii) the photoejection properties and (iv) the population of the triplet states from a singlet state via intersystem crossing to increase the lifetime of the excited state. In this work, we are interested in optimizing the ESCT properties of a betaine pyridinium chromophore substituted by a 15-aza-5-crown, that was previously shown to efficiently photoeject a Ca 2+ cation from the site 1 but no photo-recapture was observed in the site 2 [Aloïse et al. , Phys. Chem. Chem. Phys ., 2016, 22 , 15384]. To this purpose, we have investigated the impact of the modification of the site 1 on the ESCT properties by introducing different substituents (EDG groups, halogen atoms) at different positions. So far, promising systems have been identified but a simultaneous improvement of all the ESCT photoswitches properties has yet not been achieved.

Presynaptic glutamate replenishment is fundamental to brain function. In high activity regimes, such as epileptic episodes, this process is thought to rely on the glutamate-glutamine cycle between neurons and astrocytes. However the presence of an astroglial glutamine supply, as well as its functional relevance in vivo in the healthy brain remain controversial, partly due to a lack of tools that can directly examine glutamine transfer. Here, we generated a fluorescent probe that tracks glutamine in live cells, which provides direct visual evidence of an activity-dependent glutamine supply from astroglial networks to presynaptic structures under physiological conditions. This mobilization is mediated by connexin43, an astroglial protein with both gap-junction and hemichannel functions, and is essential for synaptic transmission and object recognition memory. Our findings uncover an indispensable recruitment of astroglial glutamine in physiological synaptic activity and memory via an unconventional pathway, thus providing an astrocyte basis for cognitive processes., (© 2022. The Author(s).)

Thermally activated photophysical processes are ubiquitous in numerous organic and metal-organic molecules, leading to chromophores with excited-state properties that can be considered an equilibrium mixture of the available low-lying states. Relative populations of the equilibrated states are governed by temperature. Such molecules have been devised as high quantum yield emitters in modern organic light-emitting diode technology and for deterministic excited-state lifetime control to enhance chemical reactivity in solar energy conversion and photocatalytic schemes. The recent discovery of thermally activated photophysics at CdSe nanocrystal-molecule interfaces enables a new paradigm wherein molecule-quantum dot constructs are used to systematically generate material with predetermined photophysical response and excited-state properties. Semiconductor nanomaterials feature size-tunable energy level engineering, which considerably expands the purview of thermally activated photophysics beyond what is possible using only molecules. This Perspective is intended to provide a nonexhaustive overview of the advances that led to the integration of semiconductor quantum dots in thermally activated delayed photoluminescence (TADPL) schemes and to identify important challenges moving into the future. The initial establishment of excited-state lifetime extension utilizing triplet-triplet excited-state equilibria is detailed. Next, advances involving the rational design of molecules composed of both metal-containing and organic-based chromophores that produce the desired TADPL are described. Finally, the recent introduction of semiconductor nanomaterials into hybrid TADPL constructs is discussed, paving the way toward the realization of fine-tuned deterministic control of excited-state decay. It is envisioned that libraries of synthetically facile composites will be broadly deployed as photosensitizers and light emitters for numerous synthetic and optoelectronic applications in the near future.

Molecular cages 1a and 2a incorporating a 9,10-diphenylanthracene (DPA) chromophore were synthesized through a templated ring-closure metathesis approach that allows variation in cavity size through the introduction of up to three different pillars. Reversible Diels-Alder reaction between the DPA moiety and photogenerated singlet oxygen smoothly converted 1a and 2a to the corresponding endoperoxide cages 1b and 2b , which are converted back to 1a and 2a upon heating. Endoperoxide formation constitutes a reversible covalent signal that combines structural changes in the interior of the cage with introduction of two additional coordination sites. This results in a large modulation of the binding ability of the receptors attributed to a change in the location of the preferred binding site owing to the added coordination by the endoperoxide oxygen lone pairs. Cages 1a and 2a form complexes with sodium and cesium whose association constants are modified by 4-20 fold for Na + and 200-450 fold for Cs + upon conversion to 1b and 2b . DFT calculations show that in the anthracene form, cages 1a and 2a can bind 2 metal cations in their periphery so that each cation is coordinated by 4 oxygens and one amine nitrogen, whereas the endoperoxide cages 1b and 2b bind cations centrally in a geometry that favors coordination to the endoperoxide oxygens., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The generation and transfer of triplet excitons across semiconductor nanomaterial-molecular interfaces will play an important role in emerging photonic and optoelectronic technologies, and understanding the rules that govern such phenomena is essential. The ability to cooperatively merge the photophysical properties of semiconductor quantum dots with those of well-understood and inexpensive molecular chromophores is therefore paramount. Here we show that 1-pyrenecarboxylic acid-functionalized CdSe quantum dots undergo thermally activated delayed photoluminescence. This phenomenon results from a near quantitative triplet-triplet energy transfer from the nanocrystals to 1-pyrenecarboxylic acid, producing a molecular triplet-state 'reservoir' that thermally repopulates the photoluminescent state of CdSe through endothermic reverse triplet-triplet energy transfer. The photoluminescence properties are systematically and predictably tuned through variation of the quantum dot-molecule energy gap, temperature and the triplet-excited-state lifetime of the molecular adsorbate. The concepts developed are likely to be applicable to semiconductor nanocrystals interfaced with molecular chromophores, enabling potential applications of their combined excited states.

Background: Prolonged postoperative ileus (PPOI) is a common complication after colorectal resection but data regarding PPOI risk factors after laparoscopic rectal cancer surgery is lacking. This study aimed to identify risk factors for PPOI after laparoscopic sphincter-saving total mesorectal excision (TME) for cancer., Methods: All patients who underwent a laparoscopic sphincter-saving TME for cancer from 2005 to 2014 were identified from our prospective database. PPOI was defined as abdominal distension, nausea, and/or vomiting, requiring a nasogastric tube insertion, during the postoperative period., Results: Among 428 consecutive patients, 65 patients (15%) presented with POI. In multivariate analysis, male gender (Odds Ratio (OR) 2.3 [1.1-4.5]; p = 0.026, age >70 years (OR: 2.0 [1.1-4.0]; p = 0.037)], conversion to open approach (OR 4.9 [1.5-15.4]; p = 0.007), and intra-abdominal surgical site infection (OR 3.8 [1.9-7.5]; p < 0.001) were identified as independent risk factor for PPOI. PPOI risk was 5% in patients without any risk factor but raised to 11, 28, and 54% in patients with 1, 2, or ≥3 risk factors, respectively (p < 0.001)., Conclusion: PPOI is observed in 15% of the patients after laparoscopic sphincter-saving surgery for rectal cancer. We identified four independent factors for PPOI in multivariate analysis: male, gender, age >70, conversion to open approach, and intra-abdominal surgical site infection, leading to the construction of a simple and pragmatic predictive score. This score might help the surgeon to assess patient at risk of PPOI.

The generation and transfer of triplet excitons across the molecular-semiconductor interface represents an important technological breakthrough featuring numerous fundamental scientific questions. This contribution demonstrates curious delayed formation of TIPS-pentacene molecular triplet excitons bound on the surface of PbS nanocrystals mediated through the initial production of a proposed charge transfer intermediate following selective excitation of the PbS quantum dots. Ultrafast UV-vis and near-IR transient absorption spectroscopy was used to track the dynamics of the initial PbS exciton quenching as well as time scale of the formation of molecular triplet excited states that persisted for 10 μs on the PbS surface, enabling subsequent energy and electron transfer reactivity. These results provide the pivotal proof-of-concept that PbS nanocrystals absorbing near-IR radiation can ultimately generate molecular triplets on their surfaces through processes distinct from direct Dexter triplet energy transfer. More broadly, this work establishes that small metal chalcogenide semiconductor nanocrystals interfaced with molecular chromophores exhibit behavior reminiscent of supramolecular chemical systems, a potentially impactful concept for nanoscience.

Background: After sphincter-saving operation for rectal cancer, the impact of anastomotic leakage on function has been well studied. The purpose of the present work was to assess the influence of symptomatic and asymptomatic anastomotic leakage on bowel function and health-related quality of life using the Low Anterior Resection Syndrome score and the disease-specific questionnaire European Organization for Research and Treatment of Quality of Life Questionnaire for Colorectal Cancer., Methods: The study was a case-matched study with multiple controls per case in a variable ratio from a prospectively maintained database conducted at a tertiary, colorectal operation referral center. A total of 46 patients with postoperative anastomotic leakage (symptomatic, n = 23, asymptomatic, n = 23) after laparoscopic, sphincter-saving operative intervention for rectal cancer were matched with all available patients without anastomotic leakage (control group, n = 89) using the following criteria: age, sex, type of neoadjuvant treatment, and type of anastomosis. The Low Anterior Resection Syndrome score and European Organization for Research and Treatment of Quality of Life Questionnaire for Colorectal Cancer were submitted to all included patients. The Low Anterior Resection Syndrome scores were categorized into 3 categories (no Low Anterior Resection Syndrome, minor Low Anterior Resection Syndrome, and major Low Anterior Resection Syndrome)., Results: Mean follow-up after stoma closure was 46 ± 26 months. Median (interquartile range) Low Anterior Resection Syndrome score for all included patients was 27 (16-36). Patients with symptomatic anastomotic leakage had impaired Low Anterior Resection Syndrome score: median 30 (23-39) vs 27 (15-34) in the control group (P = .02), with no Low Anterior Resection Syndrome in 4% (vs 31%), minor Low Anterior Resection Syndrome in 52% (vs 52%), and major Low Anterior Resection Syndrome in 44% (vs 17%) (P = .004). No difference was noted between the asymptomatic anastomotic leakage group and control group for median Low Anterior Resection Syndrome score (P = .70) and Low Anterior Resection Syndrome categories (no Low Anterior Resection Syndrome, minor LARS, and major Low Anterior Resection Syndrome; P = .58). Patients with symptomatic anastomotic leakage had significantly more anorectal and urinary symptoms compared with patients with no or asymptomatic anastomotic leakage., Conclusion: Symptomatic anastomotic leakage impairs function and quality of life after laparoscopic, sphincter-saving operative intervention for rectal cancer., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Triplet excitons form in quasi-2D hybrid inorganic-organic perovskites and diffuse over 100 nm before radiating with >11% photoluminescence quantum efficiency (PLQE) at low temperatures., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: Several studies showed that age is significantly associated with impaired outcomes after open colorectal surgery. However, very few data exist on laparoscopic rectal cancer surgery in elderly patients. The aim of this study was to assess operative results of laparoscopic rectal cancer surgery according to age., Methods: From 2005 to 2014, 446 consecutive patients who underwent laparoscopic rectal cancer resection were identified from a prospective database. Five groups were defined: age <45 (n = 44), 45-54 (n = 80), 55-64 (n = 166), 65-74 (n = 95) and ≥75 years (n = 61)., Results: Elderly patients presented significantly higher ASA score (p = 0.004), higher Charlson comorbidity index (p < 0.0001) and more frequent cardiovascular, pulmonary (p < 0.0001) and neurological (p = 0.03) comorbidities. Overall postoperative morbidity rate was similar between groups (34-35-37-43-43 %, p = 0.70). Medical morbidity slightly increased with age (14-9-14-19-26 %, p = 0.06), but there was no significant difference regarding clinical anastomotic leakage, surgical morbidity, major morbidity (Dindo ≥3), cardiopulmonary complications and length of hospital stay. In multivariate analysis, age was not an independent factor for postoperative morbidity, unlike ASA score ≥3 (p = 0.039), neoadjuvant radiotherapy/chemoradiotherapy (p = 0.034) and operative time ≥240 min (p = 0.013)., Conclusions: This study showed that laparoscopic rectal cancer resection might safely be performed irrespective of age.

This article proposes the exploitation of widely available, inexpensive, innocuous "green" liquid polyethylene glycol (PEG) polymers containing the oxygen scavenger oleic acid (OA) as promising media for studying oxygen-sensitive photochemical processes. Here we report the successful application of this media to detailed investigations of triplet-sensitized photochemical upconversion, previously established as being readily poisoned by dissolved oxygen. Three different PEG materials were investigated with increasing molecular weight from 200 to 600 g/mol, coded as PEG-200, PEG-400, and PEG-600. These fluidic polymers facilitate an oxygen-depleted environment in comparison to commonly employed organic solvents while providing high solubility and diffusion for the dissolved chromophores. Moreover, the low oxygen permeation afforded by these PEG solvents allows them to remain deoxygenated in open containers under ambient conditions for extended time periods. OA, 9,10-dimethylanthracene (DMA), and 2,5-dimethylfuran (DMF) are shown to efficiently and quantitatively consume dissolved oxygen in the PEG environment in the presence of the photoactivated triplet sensitizer platinum(II) tetraphenyltetrabenzoporphyrin (PtTPBP). Oxygen consumption was directly correlated with systematically increasing sensitizer excited-state lifetimes that eventually reach the same plateau as achieved through extensive N2 sparging. Diffusion-controlled bimolecular triplet-triplet energy transfer quenching between PtTPBP and the acceptor/annihilator 9,10-bisphenylethynylanthracene (BPEA) was observed in all three PEG formulations investigated. Subsequent triplet-triplet annihilation, between triplet excited BPEA acceptors, achieves bright and stable upconverted singlet fluorescence from BPEA with no decrease in intensity over 20 h under ambient conditions. In the champion composition (PEG 200), the upconversion quantum efficiency reached 31% under conditions where triplet-triplet annihilation was maximized. This is in stark contrast for the same upconverting pair measured in toluene under ambient conditions, which rapidly decomposes upon exposure to visible light. To illustrate that these PEG compositions could be translated into a suitable solid-state format, these viscous solutions were embedded in a transparent polyurethane polymer shell yielding a flexible and long-term stable upconverting cell that can be manipulated for possible real-world applications. Although the current investigation focused on photochemical upconversion, the oxygen-depleted environments developed here can be utilized to study a plethora of oxygen-intolerant photochemical reactions.

Triplet excitons are pervasive in both organic and inorganic semiconductors but generally remain confined to the material in which they originate. We demonstrated by transient absorption spectroscopy that cadmium selenide semiconductor nanoparticles, selectively excited by green light, engage in interfacial Dexter-like triplet-triplet energy transfer with surface-anchored polyaromatic carboxylic acid acceptors, extending the excited-state lifetime by six orders of magnitude. Net triplet energy transfer also occurs from surface acceptors to freely diffusing molecular solutes, further extending the lifetime while sensitizing singlet oxygen in an aerated solution. The successful translation of triplet excitons from semiconductor nanoparticles to the bulk solution implies that such materials are generally effective surrogates for molecular triplets. The nanoparticles could thereby potentially sensitize a range of chemical transformations that are relevant for fields as diverse as optoelectronics, solar energy conversion, and photobiology., (Copyright © 2016, American Association for the Advancement of Science.)

Background: This case-matched study aimed to assess the feasibility and the potential benefits of placement of a prophylactic bioprosthetic collagen porcine mesh during closure of the temporary ileostomy after total mesorectal excision (TME) for rectal cancer., Methods: From September 2012 to March 2013, 30 consecutive patients underwent placement of a retromuscular bioprosthetic mesh in the abdominal wall during closure of a diverting ileostomy after sphincter-saving laparoscopic TME for rectal cancer (mesh group). These 30 patients were matched individually to all identical patients who underwent a closure of the ileostomy without mesh after laparoscopic TME extracted from our prospective database (control group). The matching process was performed according to sex, age, body mass index, medically treated diabetes mellitus, neoadjuvant radiotherapy, and the delay between TME and closure of the ileostomy. The primary endpoint was stoma site incisional hernia, assessed in a blinded fashion by CT 1 year later., Results: Mesh placement was feasible in all mesh group patients. There was no postoperative mortality. Overall postoperative morbidity rates were similar between mesh and control groups (n = 5 [17%] vs n = 7 [11%], respectively; P = .512). On the 1-year CT, incisional hernia at the site of stomal closure was less in the mesh group (n = 1) compared with the control group (n = 12; P = .043). Reoperation for incisional hernia at the site of stomal closure was performed in 8 patients (13%) in the control group, whereas no patient from the mesh group required repair of the hernia (P = .052)., Conclusion: Placement of a bioprosthetic collagen porcine mesh during closure of the temporary ileostomy after laparoscopic TME for rectal cancer seems to decrease the chance of hernia formation at the stoma site, at least at the 1-year follow-up., (Copyright © 2015 Elsevier Inc. All rights reserved.)

A review of supramolecular and template effects on photochemical reactions in solution is presented. Photoinduced [2+2] and [4+4] cycloaddition reactions, isomerization, electron transfer and radical processes are covered, as well as examples of DNA photoligation.

Purpose: Anastomotic leakage (AL) after total mesorectal excision (TME) for rectal cancer is suspected to alter function. However, very few reports have been devoted to this problem. The aim of this study was to assess the influence of AL on function and quality of life (QoL) after laparoscopic TME for cancer., Methods: A total of 170 patients who underwent laparoscopic TME and sphincter-saving surgery for mid and low rectal cancer were included (67 % after neoadjuvant chemoradiotherapy). Twenty-one patients with AL were assessed for function and QoL (Short Form 36 (SF-36), Fecal Incontinence Quality of Life (FIQL), CR-29, and Wexner's score) at the most recent follow-up. These patients were matched to 42 patients without AL according to sex, body mass index, ypTNM, radiotherapy, and type of anastomosis., Results: After a median follow-up of 30 months, AL significantly impaired physical activity (SF-36) (p = 0.004), self-respect (FIQL) (p = 0.029), wear pad's score (Wexner's score) (p = 0.043), and blood and mucus in stool score (CR-29) (p = 0.001). Overall Wexner's score did not show any significant difference in the two groups, 8.9 in AL patients vs. 11.6 in patients without AL (p = 0.1)., Conclusion: AL significantly impairs both functional results and quality of life after laparoscopic sphincter-saving TME for rectal cancer. However, the observed difference was only limited, leading to similar outcomes on most of the tested scores. Patients with AL should be warned that if they initially experience severely impaired results, outcomes tend with time to become similar to those observed in noncomplicated patients.