Rickettsia Sca4 Reduces Vinculin-Mediated Intercellular Tension to Promote Spread.

Spotted fever group (SFG) rickettsiae are human pathogens that infect cells in the vasculature. They disseminate through host tissues by a process of cell-to-cell spread that involves protrusion formation, engulfment, and vacuolar escape. Other bacterial pathogens rely on actin-based motility to provide a physical force for spread. Here, we show that SFG species Rickettsia parkeri typically lack actin tails during spread and instead manipulate host intercellular tension and mechanotransduction to promote spread. Using transposon mutagenesis, we identified surface cell antigen 4 (Sca4) as a secreted effector of spread that specifically promotes protrusion engulfment. Sca4 interacts with the cell-adhesion protein vinculin and blocks association with vinculin's binding partner, α-catenin. Using traction and monolayer stress microscopy, we show that Sca4 reduces vinculin-dependent mechanotransduction at cell-cell junctions. Our results suggest that Sca4 relieves intercellular tension to promote protrusion engulfment, which represents a distinctive strategy for manipulating cytoskeletal force generation to enable spread.

Total Intravenous Anesthesia Is Preferred Over Volatile Agents in Cardiac Surgery.

The choice of maintenance anesthetic during cardiopulmonary bypass has been a subject of ongoing debate. Systematic reviews on the topic have so far failed to demonstrate a difference between volatile agents and total intravenous anesthesia (TIVA) in terms of mortality, myocardial injury, and neurological outcomes. Studies using animal models and noncardiac surgical populations suggest numerous mechanisms whereby TIVA has been associated with more favorable outcomes. However, even if the different anesthetic methods are assumed to equivalent in terms of patient outcomes in the context of cardiac surgery, additional factors, namely variables of occupational exposure and environmental impact, strongly support the preferred use of TIVA.

The Promise of Artificial Intelligence-Assisted Point-of-Care Ultrasonography in Perioperative Care.

The role of point-of-care ultrasonography in the perioperative setting has expanded rapidly over recent years. Revolutionizing this technology further is integrating artificial intelligence to assist clinicians in optimizing images, identifying anomalies, performing automated measurements and calculations, and facilitating diagnoses. Artificial intelligence can increase point-of-care ultrasonography efficiency and accuracy, making it an even more valuable point-of-care tool. Given this topic's importance and ever-changing landscape, this review discusses the latest trends to serve as an introduction and update in this area.

A Novel Recessive Mutation in SPEG Causes Early Onset Dilated Cardiomyopathy.

Dilated cardiomyopathy (DCM) is a common cause of heart failure and sudden cardiac death. It has been estimated that up to half of DCM cases are hereditary. Mutations in more than 50 genes, primarily autosomal dominant, have been reported. Although rare, recessive mutations are thought to contribute considerably to DCM, especially in young children. Here we identified a novel recessive mutation in the striated muscle enriched protein kinase (SPEG, p. E1680K) gene in a family with nonsyndromic, early onset DCM. To ascertain the pathogenicity of this mutation, we generated SPEG E1680K homozygous mutant human induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs) using CRISPR/Cas9-mediated genome editing. Functional studies in mutant iPSC-CMs showed aberrant calcium homeostasis, impaired contractility, and sarcomeric disorganization, recapitulating the hallmarks of DCM. By combining genetic analysis with human iPSCs, genome editing, and functional assays, we identified SPEG E1680K as a novel mutation associated with early onset DCM and provide evidence for its pathogenicity in vitro. Our study provides a conceptual paradigm for establishing genotype-phenotype associations in DCM with autosomal recessive inheritance.

Serine biosynthesis as a novel therapeutic target for dilated cardiomyopathy.

AIMS: Genetic dilated cardiomyopathy (DCM) is a leading cause of heart failure. Despite significant progress in understanding the genetic aetiologies of DCM, the molecular mechanisms underlying the pathogenesis of familial DCM remain unknown, translating to a lack of disease-specific therapies. The discovery of novel targets for the treatment of DCM was sought using phenotypic sceening assays in induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) that recapitulate the disease phenotypes in vitro. METHODS AND RESULTS: Using patient-specific iPSCs carrying a pathogenic TNNT2 gene mutation (p.R183W) and CRISPR-based genome editing, a faithful DCM model in vitro was developed. An unbiased phenotypic screening in TNNT2 mutant iPSC-derived cardiomyocytes (iPSC-CMs) with small molecule kinase inhibitors (SMKIs) was performed to identify novel therapeutic targets. Two SMKIs, Gö 6976 and SB 203580, were discovered whose combinatorial treatment rescued contractile dysfunction in DCM iPSC-CMs carrying gene mutations of various ontologies (TNNT2, TTN, LMNA, PLN, TPM1, LAMA2). The combinatorial SMKI treatment upregulated the expression of genes that encode serine, glycine, and one-carbon metabolism enzymes and significantly increased the intracellular levels of glucose-derived serine and glycine in DCM iPSC-CMs. Furthermore, the treatment rescued the mitochondrial respiration defects and increased the levels of the tricarboxylic acid cycle metabolites and ATP in DCM iPSC-CMs. Finally, the rescue of the DCM phenotypes was mediated by the activating transcription factor 4 (ATF4) and its downstream effector genes, phosphoglycerate dehydrogenase (PHGDH), which encodes a critical enzyme of the serine biosynthesis pathway, and Tribbles 3 (TRIB3), a pseudokinase with pleiotropic cellular functions. CONCLUSIONS: A phenotypic screening platform using DCM iPSC-CMs was established for therapeutic target discovery. A combination of SMKIs ameliorated contractile and metabolic dysfunction in DCM iPSC-CMs mediated via the ATF4-dependent serine biosynthesis pathway. Together, these findings suggest that modulation of serine biosynthesis signalling may represent a novel genotype-agnostic therapeutic strategy for genetic DCM.

Neuropeptides in the developing human hippocampus under hypoxic-ischemic conditions.

The perinatal period, sensitive for newborn survival, is also one of the most critical moments in human brain development. Perinatal hypoxia due to reduced blood supply to the brain (ischemia) is one of the main causes of neonatal mortality. Brain damage caused by perinatal hypoxia-ischemia (HI) can lead to neuro- and psychological disorders. However, its impact seems to be region-dependent, with the hippocampus being one of the most affected areas. Among the neuronal populations of the hippocampus, some interneuron groups - such as somatostatin- or neuropeptide Y-expressing neurons - seem to be particularly vulnerable. The limited information available about the effects of HI in the hippocampus comes mainly from animal models and adult human studies. This article presents an immunohistochemical analysis of somatostatin (SOM) and neuropeptide Y (NPY) expression in the developing human hippocampus after perinatal HI. Two rostrocaudal sections of the body of the hippocampus were analysed, and the number of immunostained cells in the polymorphic layer of the dentate gyrus (DG) and the pyramidal cell layer and stratum oriens of the CA3, CA2 and CA1 fields of the hippocampus proper were quantified. The results showed a lower density of both neuropeptides in hypoxic compared to control cases. In the HI group, the number of SOM-immunoreactive cell bodies was statistically significantly lower in the pyramidal cell layer and stratum oriens of CA1, while the number of NPY-expressing neurons was statistically lower in the pyramidal cell layer of CA2. Besides, the number of SOM-expressing neurons was significantly higher in the stratum oriens of CA1 compared to that in CA2. In sum, we observed a different vulnerability of SOM- and NPY-containing neurons in the developing human hippocampus following perinatal HI damage. Our results could contribute to a better understanding of the behaviour of these neuronal populations under stressful conditions during the perinatal period.

Three-dimensional forces exerted by leukocytes and vascular endothelial cells dynamically facilitate diapedesis.

Leukocyte transmigration across vessel walls is a critical step in the innate immune response. Upon their activation and firm adhesion to vascular endothelial cells (VECs), leukocytes preferentially extravasate across junctional gaps in the endothelial monolayer (paracellular diapedesis). It has been hypothesized that VECs facilitate paracellular diapedesis by opening their cell-cell junctions in response to the presence of an adhering leukocyte. However, it is unclear how leukocytes interact mechanically with VECs to open the VEC junctions and migrate across the endothelium. In this study, we measured the spatial and temporal evolution of the 3D traction stresses generated by the leukocytes and VECs to elucidate the sequence of mechanical events involved in paracellular diapedesis. Our measurements suggest that the contractile stresses exerted by the leukocytes and the VECs can separately perturb the junctional tensions of VECs to result in the opening of gaps before the initiation of leukocyte transmigration. Decoupling the stresses exerted by the transmigrating leukocytes and the VECs reveals that the leukocytes actively contract the VECs to open a junctional gap and then push themselves across the gap by generating strong stresses that push into the matrix. In addition, we found that diapedesis is facilitated when the tension fluctuations in the VEC monolayer were increased by proinflammatory thrombin treatment. Our findings demonstrate that diapedesis can be mechanically regulated by the transmigrating leukocytes and by proinflammatory signals that increase VEC contractility.

Medication errors and risk areas in a critical care unit.

AIMS: The aim of this study was to identify the main medication errors, their causality and the highest risk areas in critical care. DESIGN: A descriptive, longitudinal and retrospective study. METHODS: We performed a systematic analysis of the prescription, transcription and administration records of 2,634 dose units of medications that were administered to a total of 87 critically ill patients during 2018. RESULTS: Final results have shown important medication errors and a high number of significant drug interactions; prescription phase had the highest mistake rate (71%) and cause of errors (68%); transcription stage had a more variable error typology. A significant correlation was observed between the presence of causes and contributing factors to error during the prescription and the commission of errors during the nurse transcription, being the main risk areas the time of antibiotic administration, dilution errors, concentration and speed of administration of high-risk medications and the technique used for nasogastric tube drug administration. CONCLUSION: In critical care, an intolerable number of medication errors are still committed, placing the origin of many of them in the causality and contributing factors identified in the prescription stage. IMPACT: The origin of many of the medication errors and most interactions is in the prescription stage, being the nurse transcription (nurse intervention) in an important filter that prevents a considerable number of errors from finally reaching the patient. The schedule of administration of time-dependent antibiotics, high-risk medications and the technique of administering medications through a nasogastric tube are important risk areas for the commission of medication errors.

Clinical phenotypes of SARS-CoV-2: implications for clinicians and researchers.

Patients with COVID-19 present a broad spectrum of clinical presentation. Whereas hypoxaemia is the marker of severity, different strategies of management should be customised to five specific individual phenotypes. Many intubated patients present with phenotype 4, characterised by pulmonary hypoxic vasoconstriction, being associated with severe hypoxaemia with "normal" (>40 mL·cmH2O-1) lung compliance and likely representing pulmonary microvascular thrombosis. Phenotype 5 is often associated with high plasma procalcitonin and has low pulmonary compliance, Which is a result of co-infection or acute lung injury after noninvasive ventilation. Identifying these clinical phenotypes and applying a personalised approach would benefit the optimisation of therapies and improve outcomes.

Three-Dimensional Monolayer Stress Microscopy.

Many biological processes involve the collective generation and transmission of mechanical stresses across cell monolayers. In these processes, the monolayer undergoes lateral deformation and bending because of the tangential and normal components of the cell-generated stresses. Monolayer stress microscopy (MSM) methods have been developed to measure the intracellular stress distribution in cell monolayers. However, current methods assume plane monolayer geometry and neglect the contribution of bending to the intracellular stresses. This work introduces a three-dimensional (3D) MSM method that calculates monolayer stress from measurements of the 3D traction stresses exerted by the cells on a flexible substrate. The calculation is carried out by imposing equilibrium of forces and moments in the monolayer, subject to external loads given by the 3D traction stresses. The equilibrium equations are solved numerically, and the algorithm is validated for synthetic loads with known analytical solutions. We present 3D-MSM measurements of monolayer stress in micropatterned islands of endothelial cells of different sizes and shapes. These data indicate that intracellular stresses caused by lateral deformation emerge collectively over long distances; they increase with the distance from the island edge until they reach a constant value that is independent of island size. On the other hand, bending-induced intracellular stresses are more concentrated spatially and remain confined to within one to two cell lengths of bending sites. The magnitude of these bending stresses is highest at the edges of the cell islands, where they can exceed the intracellular stresses caused by lateral deformations. Our data from nonpatterned monolayers suggests that biomechanical perturbations far away from monolayer edges also cause significant localized alterations in bending tension. The localized effect of bending-induced stresses may be important in processes like cellular extravasation, which are accompanied by significant normal deflections of a cell monolayer (i.e., the endothelium) and require localized changes in monolayer permeability.

Medication errors and drug knowledge gaps among critical-care nurses: a mixed multi-method study.

BACKGROUND: Medication errors are a serious and complex problem in clinical practice, especially in intensive care units whose patients can suffer potentially very serious consequences because of the critical nature of their diseases and the pharmacotherapy programs implemented in these patients. The origins of these errors discussed in the literature are wide-ranging, although far-reaching variables are of particular special interest to those involved in training nurses. The main objective of this research was to study if the level of knowledge that critical-care nurses have about the use and administration of medications is related to the most common medication errors. METHODS: This was a mixed (multi-method) study with three phases that combined quantitative and qualitative techniques. In phase 1 patient medical records were reviewed; phase 2 consisted of an interview with a focus group; and an ad hoc questionnaire was carried out in phase 3. RESULTS: The global medication error index was 1.93%. The main risk areas were errors in the interval of administration of antibiotics (8.15% error rate); high-risk medication dilution, concentration, and infusion-rate errors (2.94% error rate); and errors in the administration of medications via nasogastric tubes (11.16% error rate). CONCLUSIONS: Nurses have a low level of knowledge of the drugs they use the most and with which a greater number of medication errors are committed in the ICU.

High throughput physiological screening of iPSC-derived cardiomyocytes for drug development.

Cardiac drug discovery is hampered by the reliance on non-human animal and cellular models with inadequate throughput and physiological fidelity to accurately identify new targets and test novel therapeutic strategies. Similarly, adverse drug effects on the heart are challenging to model, contributing to costly failure of drugs during development and even after market launch. Human induced pluripotent stem cell derived cardiac tissue represents a potentially powerful means to model aspects of heart physiology relevant to disease and adverse drug effects, providing both the human context and throughput needed to improve the efficiency of drug development. Here we review emerging technologies for high throughput measurements of cardiomyocyte physiology, and comment on the promises and challenges of using iPSC-derived cardiomyocytes to model disease and introduce the human context into early stages of drug discovery. This article is part of a Special Issue entitled: Cardiomyocyte biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

Cyclic stretch of embryonic cardiomyocytes increases proliferation, growth, and expression while repressing Tgf-ß signaling.

Perturbed biomechanical stimuli are thought to be critical for the pathogenesis of a number of congenital heart defects, including Hypoplastic Left Heart Syndrome (HLHS). While embryonic cardiomyocytes experience biomechanical stretch every heart beat, their molecular responses to biomechanical stimuli during heart development are poorly understood. We hypothesized that biomechanical stimuli activate specific signaling pathways that impact proliferation, gene expression and myocyte contraction. The objective of this study was to expose embryonic mouse cardiomyocytes (EMCM) to cyclic stretch and examine key molecular and phenotypic responses. Analysis of RNA-Sequencing data demonstrated that gene ontology groups associated with myofibril and cardiac development were significantly modulated. Stretch increased EMCM proliferation, size, cardiac gene expression, and myofibril protein levels. Stretch also repressed several components belonging to the Transforming Growth Factor-ß (Tgf-ß) signaling pathway. EMCMs undergoing cyclic stretch had decreased Tgf-ß expression, protein levels, and signaling. Furthermore, treatment of EMCMs with a Tgf-ß inhibitor resulted in increased EMCM size. Functionally, Tgf-ß signaling repressed EMCM proliferation and contractile function, as assayed via dynamic monolayer force microscopy (DMFM). Taken together, these data support the hypothesis that biomechanical stimuli play a vital role in normal cardiac development and for cardiac pathology, including HLHS.

Domino Liver Transplantation: Anesthetic Considerations for a Patient With Maple Syrup Urine Disease and Type I Diabetes Mellitus.

In this report, we describe the case of a patient with concomitant maple syrup urine disease (MSUD) and type I diabetes mellitus (T1DM) who underwent domino liver transplantation (DLT) , and the associated perioperative management. To the best of our knowledge, a DLT in an adult with both MSUD and T1DM has not been previously reported in the literature. Intensive care admission with multidisciplinary oversight is necessary for metabolic preconditioning prior to surgery. The complex interplay between these two disease processes presented with grossly elevated baseline insulin requirements and refractory intraoperative hyperglycemia. Following the successful procedure, the patient maintained excellent glycemic control on a normal diet. Four months post transplant, the patient presented with mild to moderate cellular graft rejection.

Intraoperative Tumor Migration During Renal Tumor Excision, Veno-Arterial Extracorporeal Membrane Oxygenation (V-A ECMO), and Mechanical Thrombectomy with FlowTriever.

We describe a case of a 76-year-old male with stage 3 renal cell carcinoma and known thrombus burden in his inferior vena cava (IVC) who presented for a scheduled radical right open nephrectomy with regional lymph node dissection and IVC thrombectomy. During this procedure, the patient went into pulseless-electrical activity. A trans-esophageal echocardiogram showed thrombus transit into the right atria. Emergent initiation of veno-arterial extracorporeal membrane oxygenation and mechanical embolectomy using a FlowTriever retrieval catheter was required. The patient remained intubated in critical but stable condition. Shortly afterward, he expired due to subsequent complications of massive hemorrhage and disseminated intravascular coagulopathy.

Uncertainty-Aware Traction Force Microscopy.

Traction Force Microscopy (TFM) is a versatile tool to quantify cell-exerted forces by imaging and tracking fiduciary markers embedded in elastic substrates. The computations involved in TFM are ill-conditioned, and data smoothing or regularization is required to avoid overfitting the noise in the tracked substrate displacements. Most TFM calculations depend critically on the heuristic selection of regularization (hyper)parameters affecting the balance between overfitting and smoothing. However, TFM methods rarely estimate or account for measurement errors in substrate deformation to adjust the regularization level accordingly. Moreover, there is a lack of tools to quantify how these errors propagate to the recovered traction stresses. These limitations make it difficult to interpret TFM readouts and hinder comparing different experiments. This manuscript presents an uncertainty-aware TFM technique that estimates the variability in the magnitude and direction of the traction stress vector recovered at each point in space and time of each experiment. In this technique, substrate deformation and its uncertainty are quantified using a non-parametric bootstrap PIV method by resampling the microscopy image pixels (PIV-UQ). This information is passed to a hierarchical Bayesian framework that automatically selects its hyperparameters to perform spatially adaptive regularization conditioned on image quality and propagates the uncertainty to the traction stress readouts (TFM-UQ). We validate the performance of PIV-UQ and TFM-UQ using synthetic datasets with prescribed image quality variations and demonstrate the application of PIV-UQ and TFM-UQ to experimental datasets. These studies show that TFM-UQ locally adapts the level of smoothing, outperforming traditional regularization methods. They also illustrate how uncertainty-aware TFM tools can be used to objectively choose key image analysis parameters like PIV-UQ interrogation window size. We anticipate that these tools will allow for decoupling biological heterogeneity from measurement variability and facilitate automating the analysis of large datasets by parameter-free, input data-based regularization.

Personalized transcriptome signatures in a cardiomyopathy stem cell biobank.

BACKGROUND: There is growing evidence that pathogenic mutations do not fully explain hypertrophic (HCM) or dilated (DCM) cardiomyopathy phenotypes. We hypothesized that if a patient's genetic background was influencing cardiomyopathy this should be detectable as signatures in gene expression. We built a cardiomyopathy biobank resource for interrogating personalized genotype phenotype relationships in human cell lines. METHODS: We recruited 308 diseased and control patients for our cardiomyopathy stem cell biobank. We successfully reprogrammed PBMCs (peripheral blood mononuclear cells) into induced pluripotent stem cells (iPSCs) for 300 donors. These iPSCs underwent whole genome sequencing and were differentiated into cardiomyocytes for RNA-seq. In addition to annotating pathogenic variants, mutation burden in a panel of cardiomyopathy genes was assessed for correlation with echocardiogram measurements. Line-specific co-expression networks were inferred to evaluate transcriptomic subtypes. Drug treatment targeted the sarcomere, either by activation with omecamtiv mecarbil or inhibition with mavacamten, to alter contractility. RESULTS: We generated an iPSC biobank from 300 donors, which included 101 individuals with HCM and 88 with DCM. Whole genome sequencing of 299 iPSC lines identified 78 unique pathogenic or likely pathogenic mutations in the diseased lines. Notably, only DCM lines lacking a known pathogenic or likely pathogenic mutation replicated a finding in the literature for greater nonsynonymous SNV mutation burden in 102 cardiomyopathy genes to correlate with lower left ventricular ejection fraction in DCM. We analyzed RNA-sequencing data from iPSC-derived cardiomyocytes for 102 donors. Inferred personalized co-expression networks revealed two transcriptional subtypes of HCM. The first subtype exhibited concerted activation of the co-expression network, with the degree of activation reflective of the disease severity of the donor. In contrast, the second HCM subtype and the entire DCM cohort exhibited partial activation of the respective disease network, with the strength of specific gene by gene relationships dependent on the iPSC-derived cardiomyocyte line. ADCY5 was the largest hubnode in both the HCM and DCM networks and partially corrected in response to drug treatment. CONCLUSIONS: We have a established a stem cell biobank for studying cardiomyopathy. Our analysis supports the hypothesis the genetic background influences pathologic gene expression programs and support a role for ADCY5 in cardiomyopathy.

A Devastating Floating Aortic Thrombus and Ketosis-Prone Diabetes.

This article reports a case study of a middle-aged patient diagnosed with Ketosis-Prone Diabetes (KPD) and diabetic ketoacidosis who had a mobile thrombus in the distal aortic arch with catastrophic complications from thrombus embolization. The pathogenesis of the mobile aortic thrombus is currently under investigation, with many risk factors having been found. Based on the patient's limited manifestation of atherosclerosis and the absence of any indications of thrombophilia, KPD and inflammation from uncontrolled hyperglycemia likely played a significant role in the formation of the thrombus. KPD is a subtype of diabetes characterized by the abrupt onset of severe hyperglycemia and ketoacidosis. The inflammation caused by uncontrolled hyperglycemia in KPD patients can lead to endothelial dysfunction and the activation of prothrombotic pathways. There is a lack of consensus regarding the optimal approach for managing a mobile aortic thrombus. The main strategies under consideration are conservative care, including anticoagulation alone, invasive removal of the thrombus, or endovascular intervention.

ChatGPT and Artificial Intelligence in Medical Writing: Concerns and Ethical Considerations.

Artificial intelligence (AI) language generation models, such as ChatGPT, have the potential to revolutionize the field of medical writing and other natural language processing (NLP) tasks. It is crucial to consider the ethical concerns that come with their use. These include bias, misinformation, privacy, lack of transparency, job displacement, stifling creativity, plagiarism, authorship, and dependence. Therefore, it is essential to develop strategies to understand and address these concerns. Important techniques include common bias and misinformation detection, ensuring privacy, providing transparency, and being mindful of the impact on employment. The AI-generated text must be critically reviewed by medical experts to validate the output generated by these models before being used in any clinical or medical context. By considering these ethical concerns and taking appropriate measures, we can ensure that the benefits of these powerful tools are maximized while minimizing any potential harm. This article focuses on the implications of AI assistants in medical writing and hopes to provide insight into the perceived rapid rate of technological progression from a historical and ethical perspective.

Facile Obtainment of Fluorescent PEG Hydrogels Bearing Pyrene Groups by Frontal Polymerization.

Frontal polymerization (FP) was used to prepare poly(ethylene glycol) methyl ether acrylate (PEGMA) fluorescent polymer hydrogels containing pyrenebutyl pendant groups as fluorescent probes. The polymerization procedure was carried out under solvent-free conditions, with different molar quantities of pyrenebutyl methyl ether methacrylate (PybuMA) and PEGMA, in the presence of tricaprylmethylammonium (Aliquat 336®) persulfate as a radical initiator. The obtained PEGPy hydrogels were characterized by FT-IR spectroscopy, confirming the effective incorporation of the PybuMA monomer into the polymer backbone. The thermal properties of the hydrogels were determined using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). After immersing the hydrogels in deionized water at 25 °C and pH = 7, their swelling behavior was investigated by mass gain at different pH and temperature values. The introduction of PybuMA comonomer into the hydrogel resulted in a decreased swelling ability due to the hydrophobicity of PybuMA. The optical properties of PEGPy were determined by UV-visible absorption and fluorescence spectroscopies. Both monomer and excimer emission bands were observed at 379-397 and 486 nm, respectively, and the fluorescence spectra of the PEGPy hydrogel series were recorded in different solvents to explore the coexistence of monomer and excimer emissions.