Development and validation of a nomogram for oral mucosal membrane pressure injuries in ICU patients: A prospective cohort study.

AIMS: Establishing a nomogram to estimate the probability of oral mucosal membrane pressure injury of endotracheal tube-intubated hospitalized patients in intensive care unit. DESIGN: Multicentre prospective cohort study. METHODS: Using Lasso regression and COX regression, variable selection was performed on demographic, clinical and laboratory data of 1037 ICU endotracheal tube-intubated hospitalized patients from West China Hospital, to construct a nomogram. External validation was conducted on 484 ICU endotracheal tube-intubated patients from People's Hospital of Zhongjiang County. RESULTS: Among 38 potential predictors, five variables emerged as independent predictors, integrated into the nomogram: administration of antibiotics, nutritional therapy duration, agitation, hypotension and albumin levels. CONCLUSIONS: We established a nomogram based on the hospital characteristics of ICU endotracheal tube-intubated patients, aiding in the prediction of the occurrence of oral mucosal membrane pressure injury. REPORTING METHOD: The study followed TRIPOD guidelines. RELEVANCE TO CLINICAL PRACTICE: The nomogram we developed can assist clinical worker in better identifying at-risk patients and risk factors. It enables the implementation of evidence-based nursing interventions in care to prevent the development of oral mucosal membrane pressure injury. TRIAL REGISTRATION: The study has been registered with the Chinese Clinical Trial Registry (http://www.chictr.org.cn) under registration number ChiCTR2200056615.

Effects of multicomponent exercise on quality of life, depression and anxiety among stroke survivors: A systematic review and meta-analysis.

BACKGROUND: Current guidelines stress the importance of exercise, especially multicomponent exercise to older adults with chronic conditions. AIM: To critically synthesise evidence that evaluates the effects of multicomponent exercise on quality of life, depression and anxiety after stroke. DESIGN: Systematic review and meta-analysis followed the PRISMA 2020 statement. METHODS: A systematic search of PubMed, Embase, Web of Science, Cochrane Library, CINAHL and PsycINFO from inception to 12 June 2023 was performed. Risk of bias was assessed using the Revised Cochrane risk-of-bias tool for randomised trials (RoB 2). Meta-analyses were conducted using Review Manager 5.4 and narrative syntheses were adopted whenever meta-analysis was inappropriate. The overall certainty of the evidence was rated using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. RESULTS: Of 15,351 records identified, nine were eligible and data were available for seven randomised controlled trials, three of which were identified as having a high risk of bias, one as low risk, and five as having some concerns. Subgroup pooled analyses indicated that multicomponent exercise engaged in longer exercise sessions (>60 min) was effective in improving quality of life immediately post-intervention and through 3-6 months post-intervention. However, multicomponent exercise did not significantly affect depression and anxiety. CONCLUSIONS: Multicomponent exercise with longer duration of exercise sessions has promising effects on both short- to medium-term quality of life among stroke survivors. PATIENT OR PUBLIC CONTRIBUTION: This does not apply to our work as it is a review paper. RELEVANCE TO CLINICAL PRACTICE: Healthcare providers could consider encouraging the patients to participate in multicomponent exercise sessions for more than 60 min. It is important to note that stroke survivors should be supervised by trained personnel at the beginning of the training. REGISTRATION: The protocol was registered on PROSPERO.

Early mobilisation practice in intensive care units: A large-scale cross-sectional survey in China.

BACKGROUND: The field of early rehabilitation has developed slowly in mainland China and there are limited data on the implementation of early mobilisation (EM) practice in intensive care unit (ICUs) in China. AIMS: To investigate the implementation of EM in ICUs in mainland China and to analyse its influencing factors. STUDY DESIGN: A cross-sectional electronic survey was conducted in 444 ICUs across 11 provinces in China. Head nurses provided data on institutional characteristics and EM practice in ICUs. Logistic regression models were used to identify factors associated with the implementation of EM. RESULTS: In all, 56.98% (253/444) of ICUs implemented EM with comprehensive or complete implementation in 86 ICUs. Of the 191 ICUs that did not use EM, 136 planned to implement EM in the near future. Of the 253 ICUs that used EM, 21.34% of ICUs implemented EM for all eligible patients, while 24.90% would evaluate and carry out EM within 48 h after ICU admission, 39.13% had collaborative EM teams, 34.39% reported the use of EM protocols, 14.63% reported multidisciplinary rounds and 17.39% had medical orders and charging standards for all EM activities. Only 18.18% of ICUs conducted frequent professional training for EM, and abnormal events occurred in 15.41% of ICUs during EM practice. Multivariate logistic regression analysis revealed that an economically strong province, the presence of a dedicated therapist team, more ICU beds and a higher staff-to-bed ratio favoured the implementation of EM. Furthermore, multidisciplinary rounds, well-established medical orders and charging standards, and a high frequency of professional training can lead to the comprehensive promotion and development of EM practice in ICUs. CONCLUSIONS: Both the implementation rate and quality of EM practice for critically ill patients require improvement. EM practice in Chinese ICUs is still nascent and requires development in a variety of domains. RELEVANCE TO CLINICAL PRACTICE: To facilitate the implementation of EM in ICUs, more human resources, especially the involvement of a professional therapist team, should be deployed. In addition, health providers should actively organize multidisciplinary rounds and professional training and formulate appropriate EM medical orders and charging standards.

The ability of critical care nurses to identify pressure injury and incontinence-associated dermatitis: A multicentre cross-sectional survey.

AIM: To investigate the ability of critical care nurses to identify pressure injury and incontinence-associated dermatitis and analyse the possible influencing factors. DESIGN: Cross-sectional survey. METHODS: This study was conducted at 24 hospitals across 12 provinces in China. A self-made electronic questionnaire was used. Nurses identified and judged injuries according to the information provided. RESULTS: The average identification score for pressure injury and incontinence-associated dermatitis was 9.00 ± 3.51 points, and only 2.16% of nurses scored ≥16 points. The average correct identification rate for pressure injury and incontinence-associated dermatitis was 45%. The correct identification rate for stage 1 pressure injury was the highest, while those for stage 3, stage 4, deep tissue pressure injury and unstageable pressure injury were all lower than 50%; incontinence-associated dermatitis was also easily misjudged. Nurses' educational backgrounds, professional titles, job positions, hospital levels and learning frequency were the factors that affected their ability to identify pressure injury and incontinence-associated dermatitis.

Sequential use of midazolam and dexmedetomidine for long-term sedation may reduce weaning time in selected critically ill, mechanically ventilated patients: a randomized controlled study.

BACKGROUND: Current sedatives have different side effects in long-term sedation. The sequential use of midazolam and dexmedetomidine for prolonged sedation may have distinct advantages. We aimed to evaluate the efficacy and safety of the sequential use of midazolam and either dexmedetomidine or propofol, and the use of midazolam alone in selected critically ill, mechanically ventilated patients. METHODS: This single-center, randomized controlled study was conducted in medical and surgical ICUs in a tertiary, academic medical center. Patients enrolled in this study were critically ill, mechanically ventilated adult patients receiving midazolam, with anticipated mechanical ventilation for ≥ 72 h. They passed the spontaneous breathing trial (SBT) safety screen, underwent a 30-min-SBT without indication for extubation and continued to require sedation. Patients were randomized into group M-D (midazolam was switched to dexmedetomidine), group M-P (midazolam was switched to propofol), and group M (sedation with midazolam alone), and sedatives were titrated to achieve the targeted sedation range (RASS - 2 to 0). RESULTS: Total 252 patients were enrolled. Patients in group M-D had an earlier recovery, faster extubation, and more percentage of time at the target sedation level than those in group M-P and group M (all P < 0.001). They also experienced less weaning time (25.0 h vs. 49.0 h; HR1.47, 95% CI 1.05 to 2.06; P = 0.025), and a lower incidence of delirium (19.5% vs. 43.8%, P = 0.002) than patients in group M. Recovery (P < 0.001), extubation (P < 0.001), and weaning time (P = 0.048) in group M-P were shorter than in group M, while the acquisition cost of sedative drug was more expensive than other groups (both P < 0.001). There was no significant difference in adverse events among these groups (all P > 0.05). CONCLUSIONS: The sequential use of midazolam and dexmedetomidine was an effective and safe sedation strategy for long-term sedation and could provide clinically relevant benefits for selected critically ill, mechanically ventilated patients. TRIAL REGISTRATION: NCT02528513 . Registered August 19, 2015.

Comparison of different insulin resistance surrogates to predict hyperuricemia among U.S. non-diabetic adults.

Purpose: Although it has been well-acknowledged that insulin resistance (IR) plays a critical role in the development of hyperuricemia (HU), specific relationship between IR and HU in non-diabetic patients remains rarely studied, and there is still no large-scale research regarding this issue. This study aims to explore the association between triglyceride glucose (TyG), TyG with body mass index (TyG-BMI), the ratio of triglycerides divided by high-density lipoprotein cholesterol (TG/HDL-C), metabolic score for insulin resistance (METS-IR), and the risk of HU in non-diabetic patients in The United States of America. Patients and methods: Data from the National Health and Nutrition Examination Survey (NHANES) enrolling a representative population aged ≥18-year-old were included to calculate these four indexes. Logistic regression analysis was applied to describe their associations and calculate odds ratios (OR) while the Receiver Operating Characteristic curve was utilized to assess the prediction ability of these four indexes. Results: A total of 7,743 people (3,806 males and 3,937 females, mean age: 45.17 ± 17.10 years old) were included in this study, among whom 32.18% suffered from HU. After adjustment for sex, age, ethnicity, education background, smoking status, drinking status, systolic blood pressure (SBP), diastolic blood pressure (DBP), metabolic equivalent values (METs), total cholesterol, low-density lipoprotein cholesterol, and estimated glomerular filtration rate, it showed that all four indexes were closely related to HU. Compared with the lowest quartile, OR of the highest quartile of these four indicators for HU were as following respectively: TyG: 5.61 (95% CI: 4.29-7.32); TyG-BMI: 7.15 (95% CI: 5.56-9.20); TG/HDL-C: 4.42 (95% CI: 3.49-5.60); METS-IR: 7.84 (95% CI: 6.07-10.13). TyG, TyG-BMI, TG/HDL-C and METS-IR had moderate discrimination ability for HU, with an AUC value of 0.66 (95% CI: 0.65-0.68), 0.67 (95% CI: 0.65-0.68), 0.68 (95% CI: 0.67-0.69) and 0.68 (95% CI: 0.66-0.69) respectively. Each index showed better prediction ability for HU risk in females than in males. Conclusion: It was found that the risk of HU was positively associated with the elevation of TyG, TyG-BMI, TG/HDL-C and METS-IR in a large-scale population of U.S., and TyG-BMI and METS-IR have a better ability to identify HU in both genders.

Factors influencing nurses' behavioral intention toward caring for COVID-19 patients on mechanical ventilation: A cross-sectional study.

OBJECTIVES: To investigate nurses' behavioral intention toward caring for COVID-19 patients on mechanical ventilation, as well as the factors affecting their intention. BACKGROUND: COVID-19 patients undergoing mechanical ventilation have many care needs and pose more challenges for nurses, which might adversely affect nurses' intention toward caring behavior. METHODS: A cross-sectional study was conducted by using simple random sampling to recruit 598 nurses from five tertiary hospitals in Sichuan Province, China. The participants responded to an online questionnaire that included questions on demographic characteristics; the Attitude, Subjective Norms, and Behavioral Intention of Nurses toward Mechanically Ventilated Patients (ASIMP) questionnaire; the Nursing Professional Identity Scale (NPIS); and the Compassion Fatigue-Short Scale (CF-Short Scale). ANOVA, Spearman correlation analysis, and multiple linear regression were performed to analyze the data. RESULTS: The mean total behavioral intention score was 179.46 (± 14.83) out of a total score of 189.00, which represented a high level of intention toward caring for patients on mechanical ventilation. Multiple linear regression revealed that subjective norms (ß = 0.390, P<0.001), perceived behavioral control (ß = 0.149, P<0.001), professional identity (ß = 0.101, P = 0.009), and compassion fatigue (ß = 0.088 P = 0.024) were significant predictors of nurses' behavioral intention. CONCLUSIONS: Most nurses have a positive behavioral intention to care for COVID-19 patients undergoing mechanical ventilation. The findings in this study provide some insight for developing effective and tailored strategies to promote nurses' behavioral intention toward caring for ventilated patients under the pandemic situation.

Well-orientation strategy for direct binding of antibodies: Development of the immunochromatographic test using the antigen modified Fe2O3 nanoprobes for sensitive detection of aflatoxin B1.

One of the major concerns in the application of nanocarriers in biosensing is the impair of the recognition molecules bioactivity loaded on their surfaces due to harsh and laborious cross-linking and random orientation, resulting in unsatisfactory sensitivity. Herein, we proposed a novel immunochromatographic test strip (FNS-ag-DICTS) by taking advantage of the antigen (ag) modified Fe2O3 nanostructures (FNSs) as new signal tags and goat anti-mouse IgG labeling on the detection line instead of ag, which was used for sensitive detection of aflatoxin B1 (AFB1). The fabricated FNS-ag can orientate the Fab region of monoclonal antibodies (mAbs), waiving the intrinsic limitations of traditional nanomaterials labeled mAbs. Under optimal conditions, FNS-ag-DICTS possessed excellent specificity and a wide detection range, with a visual limit of detection (vLOD) of 0.0125 ng mL-1. In addition, the biosensor successfully detected AFB1 in peanut, green bean and corn, with an average recovery rate of 82.8-124.9%.

Diverse Dyes-Embedded Staphylococcus aureus as Potential Biocarriers for Enhancing Sensitivity in Biosensing.

Nanomaterials-based immunochromatographic assays (ICAs) have gained great commercial success in real-life point-of-care testing (POCT). Exploring novel carriers of ICAs with improved signaling and sustained activity favors the development of sensitive POCT. Herein a potent signal biotag, colored Staphylococcus aureus (SA), was created for ICA carriers through a mild self-assembly strategy, providing high luminance and abundant specific binding sites for immobilization of monoclonal antibodies (mAbs). The biocompatible SA-dyes (SADs) retained both an intact surface structure for mAbs labeling (Fc portion) and the superior bioactivity of immobilized mAbs (affinity constant was about 109 M-1), thus waiving the intrinsic limitations of traditional nanomaterials and endowing high sensitivity. Proof-of-concept was demonstrated by employing Congo red- or/and fluorescein isothiocyanate-embedded SA (SACR, SAFITC, and SACR-SAFITC) as ICA carriers to detect zearalenone (ZEN) through colorimetric or/and fluorimetric signals. Furthermore, the ICAs satisfied the clinical requirement perfectly, including limit of detection (0.013 ng/mL, which was at least an 85-fold improvement over that of traditional gold nanoparticles-based ICA), linearity (R2 > 0.98), reproducibility (RSD < 8%), selectivity, and stability. Importantly, the proposed biosensors could be well-applied in four real samples for ZEN monitoring with satisfactory recoveries, correlating well with the results from liquid chromatography-tandem mass spectrometry (LC-MS). This work also proved a universal design for tailoring coloration bands for SAD-ICA detection of multiple analytes.

Metal-polydopamine framework based lateral flow assay for high sensitive detection of tetracycline in food samples.

Gold nanoparticles (AuNPs)-based lateral flow assay (LFA) enables a rapid detection of tetracycline (TET) in food samples but suffers from low sensitivity. Herein, metal-polydopamine framework (MPF), as a label, was employed to load monoclonal antibodies (mAbs) directly as the probe in LFA for highly sensitive sensing of TET. Combining zeolitic imidazolate framework (ZIF-67) and polydopamine (PDA), a stable MPF with large size, well water-dispersible, excellent affinity and optical properties was prepared through a versatile layer-by-layer assembly (LLA) strategy. Under optimized conditions, the biosensor (MPF-LFA) exhibited a great linear relationship in the range of 0.09-6 ng/mL and a detection limit of 0.045 ng/mL for TET detection, which was over 66-fold more sensitive than traditional AuNPs based LFA. Furthermore, the MPF-LFA was successfully applied to the screening of TET in fish, chicken, milk and shrimp samples with satisfied recoveries from 91% to 114%.

An innovative prussian blue nanocubes decomposition-assisted signal amplification strategy suitable for competitive lateral flow immunoassay to sensitively detect aflatoxin B1.

A prussian blue nanocubes decomposition-assisted signal amplification strategy for competitive lateral flow immunoassay (PBNCD-SALFIA) was innovatively proposed to analyze aflatoxin B1 (AFB1) in foodstuffs. The signal was amplified on account of the PBNCs can degrade and fade under alkaline condition, which could weak the color of the test- and control-lines, thereby improving the sensitivity of the sensor. The strategy was technically-simple, just using NaOH as an amplifier can realize signal amplification in the competition assay. Under optimized conditions, the enhanced strip exhibited excellent specificity and sensitivity in AFB1 monitoring with a detection limit of 23 pg/mL, which was approximately 4- and 8-folds lower than those of PBNCs-LFIA (90 pg/mL) and conventional gold nanoparticles-LFIA (175 pg/mL), respectively. Taking the advantage of the color-fading, this platform revealing the lowest detectable concentration of 0.184, 0.368 and 0.184 µg/kg for AFB1 in corn, peanut and pumpkin seed within 58 min, separately, showing reliable results.

Prevalence and associated factors of depression and anxiety among nurses during the outbreak of COVID-19 in China: A cross-sectional study.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is a public health emergency of international concern and has caused traumatic experience for nurses worldwide. However, the prevalence of depression and anxiety symptoms in nurses, and how psychosocial factors influence nurses in this public crisis are unknown. OBJECTIVES: To determine the effect of COVID-19 on the mental health of nurses and the prevalence of anxiety and depression symptoms among nurses in China during the outbreak. DESIGN: A cross-sectional study. SETTINGS AND PARTICIPANTS: A total of 3,228 nurses in Sichuan Province and Wuhan City were selected by convenience sampling. All participants were invited to complete the questionnaire through WeChat from January 27 to February 3, 2020. METHODS: A self-reported questionnaire combining depression and anxiety scale was used to collect data anonymously. Binary and multivariate logistic regression was applied to measure the odds of psychosocial factors of anxiety and depression and perceived health, respectively. RESULTS: The total incidence of depression (34.3%) and anxiety (18.1%) during the COVID-19 outbreak was lower than that during the SARS outbreak; however, the rate of depression in our study (47.1%) was high and similar in a recent study (50.4%) about the health care workers exposed to COVID-19 in China. The results indicated that COVID-19-related stress, relationship quality with family, and demographic characteristics were associated with depression, anxiety, and perceived health status. Furthermore, the prevalence of depression was similar between nurses working in low-risk COVID-19 wards was as high as working in high-risk COVID-19 wards (OR, 1.078; 95% CI, 0.784-1.481). CONCLUSIONS: Our study revealed the high prevalence of depression and anxiety among nurses during the outbreak of COVID-19. COVID-19 factors and psychosocial factors were associated with mental health of nurses. The results suggest that hospitals should implement effective mental health promotion programs focused on occupational safety and family support to improve the well-being of nurses.

Gold nanoparticles-functionalized three-dimensional flower-like manganese dioxide: A high-sensitivity thermal analysis immunochromatographic sensor.

A sensitive photothermal immunochromatographic test strip (PITS) for the detection of deoxynivalenol (DON) was developed using flower-like gold nanoparticle-deposited manganese dioxide nanocarrier (FMD-G NC) labeled antibodies (Abs) as the photothermal-sensing probe. FMD was used as a template to deposit small gold nanoparticles (GNPs) to synthesize FMD-G NC with large specific surface area and significant photothermal conversion property. The FMD-G-Ab probe was competitively captured by DON target and antigen coated on test line (T-line), forming colorimetric signals under naked eyes and photothermal signals under an 808 nm laser. Under optimal conditions, the PITS exhibited sensitive and specific detection of DON from 0.19 ng mL-1 to 12 ng mL-1 with detection limits of 0.013 ng mL-1, which were over 15-fold and 58-fold more sensitive than visual FMD-G-ITS and traditional GNPs-ITS. In addition, the novel FMD-G-PITS possessed a universal applicability, which could be well applied in green bean, corn, and millet.

Polydopamine coated zirconium metal-organic frameworks-based immunochromatographic assay for highly sensitive detection of deoxynivalenol.

Conventional immunochromatographic assays (ICAs) based on gold nanoparticles (GNPs) suffer from the disadvantage of low sensitivity. In this work, a highly sensitive ICA based on polydopamine coated zirconium metal-organic frameworks labeled antibodies (ZrPA-Ab) as a novel probe was developed for visual determination of deoxynivalenol (DON). The ZrPA was synthesized via an oxidative self-polymerized assembly (OPMA) strategy using porphyrin functionalized zirconium metal-organic frameworks (Zr-MOFs, MOF-525) and polydopamine (PDA). The Abs could directly attach to the ZrPA surface owing to the large specific surface area, excellent water-stability and bio-compatibility of the ZrPA, on this basis, a sensitive, precise and reliable immunoassay method can be developed for rapid and selective detection of DON. Under optimized conditions, a non-linear calibration curve was obtained in the range of 0-50 ng/mL DON concentration with an IC50 of 1.22 ng/mL, and the visual detection limit was 0.18 ng/mL, which was about 8-times more sensitive than that of the conventional GNPs-based ICA. Finally, the proposed ZrPA-ICA was successfully applied for the detection of DON in pig hind legs meat, green bean, maize and millet samples, revealing the feasible and reliable application of this biosensor in different food matrices. Thus, this work broadens the possibilities for the use of MOFs as a novel labeling carrier in immunoassays.

Fe3O4@CuS-based immunochromatographic test strips and their application to label-free and dual-readout detection of Escherichia coli O157:H7 in food.

Herein, a label-free and dual-readout immunochromatographic test strip (ITS) for the sensitive detection of Escherichia coli (E. coli) O157:H7 by taking advantages of the strong capture ability of Fe3O4@CuS nanostructures (NSs) towards bacteria and their ultrahigh photothermal effects (PTEs) was reported. Especially, without the customarily antibody (Ab)-labeled probe, Fe3O4@CuS NSs could be adsorbed onto the surfaces of bacteria to form Fe3O4@CuS-bacteria conjugates and then trapped by immobilized Abs on the test line (T-line), forming a characteristic yellow band. After direct immunoreactions, the PTEs of Fe3O4@CuS NSs endowed T-line to be irradiated by an 808 nm infrared light, obtaining satisfactory sensitivity and accuracy. Under optimal conditions, E. coli O157:H7, as low as 103 and 102 CFU/mL, could be monitored in colorimetric and photothermal modes. Additionally, E. coli O157:H7 was successfully detected in beef, chicken, milk and honey samples by this proposed platform with a recovery of 80-120%.

Diversely positive-charged gold nanoparticles based biosensor: A label-free and sensitive tool for foodborne pathogen detection.

Gold nanoparticles (AuNPs)-based lateral flow strip (LFS) enables a quick screening of foodborne bacteria in point-of-care (POC) diagnostics but suffers from the cumbersome labeling of antibodies and poor sensitive performance. Here, we innovated a label-free immunoassay to detect pathogenic bacteria by introducing diversely positive charges functionalized AuNPs ((+) AuNPs). The (+) AuNPs can be loaded on negatively charged bacteria via electrostatic interaction, leading to a color labeling to target bacteria. Afterward, the (+) AuNPs-bacteria complex can be specifically captured by monoclonal antibody (McAb) immobilized on test (T)-line. Under optimum conditions, the proposed LFS exhibited a lowest detectable concentration of 103 CFU/mL for Salmonella enteritidis (S. enteritidis) and could be well applied in drinking water, lettuce and pork samples. Moreover, this novel (+) AuNPs-LFS possessed a universal applicability, which could also be used for detecting Escherichia coli O157 (E. coli O157) with a superior sensitivity (104 CFU/mL) and specificity.

Diblock copolymer micelles and supported films with noncovalently incorporated chromophores: a modular platform for efficient energy transfer.

We report generation of modular, artificial light-harvesting assemblies where an amphiphilic diblock copolymer, poly(ethylene oxide)-block-poly(butadiene), serves as the framework for noncovalent organization of BODIPY-based energy donor and bacteriochlorin-based energy acceptor chromophores. The assemblies are adaptive and form well-defined micelles in aqueous solution and high-quality monolayer and bilayer films on solid supports, with the latter showing greater than 90% energy transfer efficiency. This study lays the groundwork for further development of modular, polymer-based materials for light harvesting and other photonic applications.

Hierarchical cooperative binary ionic porphyrin nanocomposites.

Cooperative binary ionic (CBI) solids comprise a versatile new class of opto-electronic and catalytic materials consisting of ionically self-assembled pairs of organic anions and cations. Herein, we report CBI nanocomposites formed by growing nanoparticles of one type of porphyrin CBI solid onto a second porphyrin CBI substructure with complementary functionality.

Binary ionic porphyrin nanosheets: electronic and light-harvesting properties regulated by crystal structure.

Crystalline solids self-assembled from anionic and cationic porphyrins provide a new class of multifunctional optoelectronic micro- and nanomaterials. A 1 : 1 combination of zinc(II) tetra(4-sulfonatophenyl)porphyrin (ZnTPPS) and tin(IV) tetra(N-methyl-4-pyridiniumyl)porphyrin (SnTNMePyP) gives porphyrin nanosheets with high aspect ratios and varying thickness. The room temperature preparation of the nanosheets has provided the first X-ray crystal structure of a cooperative binary ionic (CBI) solid. The unit cell contains one and one-half molecules of aquo-ZnTPPS(4-) (an electron donor) and three half molecules of dihydroxy-SnTNMePyP(4+) (an electron acceptor). Charge balance in the solid is reached without any non-porphyrinic ions, as previously determined for other CBI nanomaterials by non-crystallographic means. The crystal structure reveals a complicated molecular arrangement with slipped π-π stacking only occurring in isolated dimers of one of the symmetrically unique zinc porphyrins. Consistent with the crystal structure, UV-visible J-aggregate bands indicative of exciton delocalization and extended π-π stacking are not observed. XRD measurements show that the structure of the Zn/Sn nanosheets is distinct from that of Zn/Sn four-leaf clover-like CBI solids reported previously. In contrast with the Zn/Sn clovers that do exhibit J-aggregate bands and are photoconductive, the nanosheets are not photoconductive. Even so, the nanosheets act as light-harvesting structures in an artificial photosynthesis system capable of reducing water to hydrogen but not as efficiently as the Zn/Sn clovers.

Morphological families of self-assembled porphyrin structures and their photosensitization of hydrogen generation.

Varying the solution growth conditions of cooperative binary ionic solids composed of anionic and cationic metalloporphyrins produces a series of families of self-assembled structures that efficiently and durably photosensitize the evolution of hydrogen.