Triploid Pacific oysters exhibit stress response dysregulation and elevated mortality following heatwaves.

Polyploidy has been suggested to negatively impact environmental stress tolerance, resulting in increased susceptibility to extreme climate events. In this study, we compared the genomic and physiological response of diploid (2n) and triploid (3n) Pacific oysters (Crassostrea gigas) to conditions present during an atmospheric heatwave that impacted the Pacific Northwestern region of the United States in the summer of 2021. Climate stressors were applied either singly (single stressor; elevated seawater temperature, 30°C) or in succession (multiple stressor; elevated seawater temperature followed by aerial emersion at 44°C), replicating conditions present within the intertidal over a tidal cycle during the event. Oyster mortality rate was elevated within stress treatments with respect to the control and was significantly higher in triploids than diploids following multiple stress exposure (36.4% vs. 14.8%). Triploids within the multiple stressor treatment exhibited signs of energetic limitation, including metabolic depression, a significant reduction in ctenidium Na+ /K+ ATPase activity, and the dysregulated expression of genes associated with stress response, innate immunity, glucose metabolism, and mitochondrial function. Functional enrichment analysis of ploidy-specific gene sets identified that biological processes associated with metabolism, stress tolerance, and immune function were overrepresented within triploids across stress treatments. Our results suggest that triploidy impacts the transcriptional regulation of key processes that underly the stress response of Pacific oysters, resulting in downstream shifts in physiological tolerance limits that may increase susceptibility to extreme climate events that present multiple environmental stressors. The impact of chromosome set manipulation on the climate resilience of marine organisms has important implications for domestic food security within future climate scenarios, especially as triploidy induction becomes an increasingly popular tool to elicit reproductive control across a wide range of species used within marine aquaculture.

Minimal in vivo requirements for developmentally regulated cardiac long intergenic non-coding RNAs.

Long intergenic non-coding RNAs (lincRNAs) have been implicated in gene regulation, but their requirement for development needs empirical interrogation. We computationally identified nine murine lincRNAs that have developmentally regulated transcriptional and epigenomic profiles specific to early heart differentiation. Six of the nine lincRNAs had in vivo expression patterns supporting a potential function in heart development, including a transcript downstream of the cardiac transcription factor Hand2, which we named Handlr (Hand2-associated lincRNA), Rubie and Atcayos We genetically ablated these six lincRNAs in mouse, which suggested genomic regulatory roles for four of the cohort. However, none of the lincRNA deletions led to severe cardiac phenotypes. Thus, we stressed the hearts of adult Handlr and Atcayos mutant mice by transverse aortic banding and found that absence of these lincRNAs did not affect cardiac hypertrophy or left ventricular function post-stress. Our results support roles for lincRNA transcripts and/or transcription in the regulation of topologically associated genes. However, the individual importance of developmentally specific lincRNAs is yet to be established. Their status as either gene-like entities or epigenetic components of the nucleus should be further considered.

Frailty index predicts long-term mortality and postoperative complications in patients undergoing endovascular aortic aneurysm repair.

OBJECTIVE: The Risk Analysis Index (RAI) has been used to evaluate preoperative frailty, which is associated with poor short- and long-term outcomes. We assessed this tool's ability to predict postoperative outcomes after endovascular aortic aneurysm repair. METHODS: Institutional Review Board approval was obtained for this retrospective study. All patients who underwent elective endovascular aneurysm repair at a single Veterans Affairs Medical Center from December 2010 to March 2016 were included. Patients' characteristics and clinical data were retrospectively collected and analyzed. The RAI score was calculated from preoperative data, and a standard cutoff value (RAI ≥30) was used to determine frailty. Outcomes including postoperative complications, delayed discharge, and survival were compared between frail and nonfrail groups. Multivariate analysis was performed to evaluate preoperative factors associated with these outcomes. RESULTS: There were 134 patients who met inclusion criteria. There were 44 frail patients (RAI ≥30) and 90 nonfrail patients (RAI <30). Frail patients had a longer hospital stay (3.9 ± 4.0 days vs 2.3 ± 1.6 days; P = .02), increased operative time (155 ± 30 minutes vs 138 ± 30 minutes; P = .002), and increased postoperative complications (43% vs 21%; P = .02) compared with nonfrail patients. Kaplan-Meier average survival for frail patients and nonfrail patients was 60 ± 4 months and 84 ± 3 months (P < .001), respectively. In multivariate analyses, frailty was associated with worse overall survival (hazard ratio, 3.7; 95% confidence interval [CI], 1.8-7.3) and higher odds of complications (odds ratio, 1.1; 95% CI, 1.0-1.14) and delayed discharge (odds ratio, 1.1; 95% CI, 1.05-1.2). CONCLUSIONS: Preoperative frailty as evaluated by the RAI is associated with worse short-term postoperative outcomes and long-term mortality. The RAI can be used to inform risk-benefit discussions with patients and their families.

Environmental post-processing increases the adhesion strength of mussel byssus adhesive.

Marine mussels (Mytilus trossulus) attach to a wide variety of surfaces underwater using a protein adhesive that is cured by the surrounding seawater environment. In this study, the influence of environmental post-processing on adhesion strength was investigated by aging adhesive plaques in a range of seawater pH conditions. Plaques took 8-12 days to achieve full strength at pH 8, nearly doubling in adhesion strength (+94%) and increasing the work required to dislodge (+59%). Holding plaques in low pH conditions prevented strengthening, causing the material to tear more frequently under tension. The timescale of strengthening is consistent with the conversion of DOPA to DOPA-quinone, a pH dependent process that promotes cross-linking between adhesive proteins. The precise arrangement of DOPA containing proteins away from the adhesive-substratum interface emphasizes the role that structural organization can have on function, an insight that could lead to the design of better synthetic adhesives and metal-coordinating hydrogels.

Novel drug design for Chagas disease via targeting Trypanosoma cruzi tubulin: Homology modeling and binding pocket prediction on Trypanosoma cruzi tubulin polymerization inhibition by naphthoquinone derivatives.

Chagas disease, also called American trypanosomiasis, is a parasitic disease caused by Trypanosoma cruzi (T. cruzi). Recent findings have underscored the abundance of the causative organism, (T. cruzi), especially in the southern tier states of the US and the risk burden for the rural farming communities there. Due to a lack of safe and effective drugs, there is an urgent need for novel therapeutic options for treating Chagas disease. We report here our first scientific effort to pursue a novel drug design for treating Chagas disease via the targeting of T. cruzi tubulin. First, the anti T. cruzi tubulin activities of five naphthoquinone derivatives were determined and correlated to their anti-trypanosomal activities. The correlation between the ligand activities against the T. cruzi organism and their tubulin inhibitory activities was very strong with a Pearson's r value of 0.88 (P value <0.05), indicating that this class of compounds could inhibit the activity of the trypanosome organism via T. cruzi tubulin polymerization inhibition. Subsequent molecular modeling studies were carried out to understand the mechanisms of the anti-tubulin activities, wherein, the homology model of T. cruzi tubulin dimer was generated and the putative binding site of naphthoquinone derivatives was predicted. The correlation coefficient for ligand anti-tubulin activities and their binding energies at the putative pocket was found to be r=0.79, a high correlation efficiency that was not replicated in contiguous candidate pockets. The homology model of T. cruzi tubulin and the identification of its putative binding site lay a solid ground for further structure based drug design, including molecular docking and pharmacophore analysis. This study presents a new opportunity for designing potent and selective drugs for Chagas disease.

A comparison of model-free phase I dose escalation designs for dual-agent combination therapies.

It is increasingly common for therapies in oncology to be given in combination. In some cases, patients can benefit from the interaction between two drugs, although often at the risk of higher toxicity. A large number of designs to conduct phase I trials in this setting are available, where the objective is to select the maximum tolerated dose combination. Recently, a number of model-free (also called model-assisted) designs have provoked interest, providing several practical advantages over the more conventional approaches of rule-based or model-based designs. In this paper, we demonstrate a novel calibration procedure for model-free designs to determine their most desirable parameters. Under the calibration procedure, we compare the behaviour of model-free designs to model-based designs in a comprehensive simulation study, covering a number of clinically plausible scenarios. It is found that model-free designs are competitive with the model-based designs in terms of the proportion of correct selections of the maximum tolerated dose combination. However, there are a number of scenarios in which model-free designs offer a safer alternative. This is also illustrated in the application of the designs to a case study using data from a phase I oncology trial.

Evolutionary variation in the mechanics of fiddler crab claws.

BACKGROUND: Fiddler crabs, genus Uca, are classic examples of how intense sexual selection can produce exaggerated male traits. Throughout the genus the enlarged "major" cheliped (claw) of the male fiddler crab is used both as a signal for attracting females and as a weapon for combat with other males. However, the morphology of the major claw is highly variable across the approximately 100 species within the genus. Here we address variation, scaling, and correlated evolution in the mechanics of the major claw by analyzing the morphology and mechanical properties of the claws of 21 species of fiddler crabs from the Pacific, Gulf and Atlantic coasts of the Americas. RESULTS: We find that the mechanics that produce claw closing forces, the sizes of claws and the mechanical strength of the cuticle of claws are all highly variable across the genus. Most variables scale isometrically with body size across species but claw force production scales allometrically with body size. Using phylogenetically independent contrasts, we find that the force that a claw can potentially produce is positively correlated with the strength of the cuticle on the claw where forces are delivered in a fight. There is also a negative correlation between the force that a claw can potentially produce and the size of the claw corrected for the mass of the claw. CONCLUSIONS: These relationships suggest that there has been correlated evolution between force production and armoring, and that there is a tradeoff between claw mechanics for signaling and claw mechanics for fighting.

Role of Temporal artery biopsy in a sequential Giant Cell Arteritis fast-track pathway: a 5-year prospective study.

BACKGROUND: Increasing number of centres are establishing sequential fast track pathways (FTP) for management of giant cell arteritis (GCA), with temporal artery ultrasound (US) replacing temporal artery biopsy (TAB) as the first investigational method. Biopsy is performed as second investigation, when US is negative/inconclusive. This study investigates the role of TAB in a sequential GCA-FTP and its utility in those with negative/inconclusive US. METHODS: Prospective study of patients referred for TAB as part of Coventry sequential GCA-FTP May 2014-June 2019. Analysis included sensitivity and specificity of TAB, impact of arterial specimen length and duration of treatment with corticosteroids on sensitivity of TAB and the clinical predictors for a positive biopsy. RESULTS: A total of 1149 patients with suspected GCA were referred to this GCA-FTP, with 109 (9.5%) referred for TAB. Overall sensitivity of TAB was 47% (specificity: 100%) and in patients with negative/inconclusive US sensitivity was 39% (specificity:100%). Post-fixation arterial specimen length <15 mm showed lower sensitivity (14%), which increased to 52% when specimen length was ≥15 mm. Sensitivity of TAB was highest in first 7 (60%) to 10 days (59%) from starting corticosteroids. Predictors of positive biopsy using univariate logistic regression analysis were jaw claudication (OR = 5.40; p = 0.0057), elevated erythrocyte sedimentation rate (OR = 5.50; p = 0.013) and elevated C-reactive protein (OR = 23.7; p = 0.0043). CONCLUSION: This is the first study to look at the role of TAB in a sequential GCA-FTP. Biopsy plays an important role in GCA-FTP, when US is negative/inconclusive. Sensitivity of TAB improved when specimen length was ≥15 mm and performed within 10 days of commencing corticosteroids.

Injectable pH-responsive adhesive hydrogels for bone tissue engineering inspired by the underwater attachment strategy of marine mussels.

A major challenge in tissue engineering is the development of alternatives to traditional bone autografts and allografts that can regenerate critical-sized bone defects. Here we present the design of injectable pH-responsive double-crosslinked adhesive hydrogels inspired by the molecular mechanism and environmental post-processing of marine mussel adhesive. Nine adhesive hydrogel formulations were developed through the conjugation of crosslinkable catechol functional groups (DOPA) and the synthetic oligomer oligo[poly(ethylene glycol) fumarate] (OPF), varying the DOPA content (w/w%) and molecular weight (MW) of the OPF backbone to produce formulations with a range of swelling ratios, porosities, and crosslink densities. DOPA incorporation altered the surface chemistry, mechanical properties, and surface topography of hydrogels, resulting in an increase in material stiffness, slower degradation, and enhanced pre-osteoblast cell attachment and proliferation. When injected within simulated bone defects, DOPA-mediated interfacial adhesive interactions also prevented the displacement of scaffolds, an effect that was maintained even after swelling within physiological conditions. Taken together, OPF-DOPA hydrogels represent a promising new material to enhanced tissue integration and the prevention of the post-implantation migration of scaffolds that can occur due to biomechanical loading in vivo.

Genome Editing Human Pluripotent Stem Cells to Model ß-Cell Disease and Unmask Novel Genetic Modifiers.

A mechanistic understanding of the genetic basis of complex diseases such as diabetes mellitus remain elusive due in large part to the activity of genetic disease modifiers that impact the penetrance and/or presentation of disease phenotypes. In the face of such complexity, rare forms of diabetes that result from single-gene mutations (monogenic diabetes) can be used to model the contribution of individual genetic factors to pancreatic ß-cell dysfunction and the breakdown of glucose homeostasis. Here we review the contribution of protein coding and non-protein coding genetic disease modifiers to the pathogenesis of diabetes subtypes, as well as how recent technological advances in the generation, differentiation, and genome editing of human pluripotent stem cells (hPSC) enable the development of cell-based disease models. Finally, we describe a disease modifier discovery platform that utilizes these technologies to identify novel genetic modifiers using induced pluripotent stem cells (iPSC) derived from patients with monogenic diabetes caused by heterozygous mutations.

Exploring the perceptions, attitude and experiences of adolescents, their parents and teachers towards sugar sweetened beverages consumption in the National Capital Region of Delhi.

OBJECTIVE: To understand perceptions, attitudes and experiences of school-going adolescents, their parents, teachers and school management towards sugar-sweetened beverages (SSBs). DESIGN: An exploratory qualitative study was undertaken. SETTING: The study was conducted in selected, mixed, unaided schools in the state of Delhi. SUBJECTS: Students of classes 8 to 12th, principals of schools, teachers, parents and school canteen owners. RESULTS: SSBs formed an integral part of the diet of adolescents due to its taste and role as a thirst quencher. Respondents had a fair knowledge of health effects of SSBs. However, they were not aware of the range of drinks that constitute SSBs. Respondents associated SSBs with positivity and happiness. Promotion of SSBs by sports and film stars was cited as a major driver influencing consumption of SSBs by young people. CONCLUSIONS: SSBs were readily available even though schools had put in measures to restrict their availability in the premises. Peer pressure emerged as a key factor that drove the consumption of SSBs. Advertisements for SSBs involved individuals who were considered role models and these focused on themes that were important for young people such as belongingness, machismo and friendship among others. On the contrary, health promotion messages around obesity or the consumption of SSBs hardly had any brand ambassador or the visibility of campaigns that promoted SSBs.

Enhanced nerve cell proliferation and differentiation on electrically conductive scaffolds embedded with graphene and carbon nanotubes.

Conduits that promote nerve regeneration are currently of great medical concern, particularly when gaps exist between nerve endings. To address this issue, our laboratory previously developed a nerve conduit from biodegradable poly(caprolactone fumarate) (PCLF) that supports peripheral nerve regeneration. The present study improves upon this work by further developing an electrically conductive, positively charged PCLF scaffold through the incorporation of graphene, carbon nanotubes (CNTs), and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MTAC) (PCLF-Graphene-CNT-MTAC) using ultraviolet (UV) induced photocrosslinking. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy were used to assess the incorporation of CNTs and graphene into PCLF-Graphene-CNT-MTAC scaffolds, which displayed enhanced surface roughness and reduced electrochemical impedance when compared to neat PCLF. Scaffolds with these surface modifications also showed improved growth and differentiation of rat pheochromocytoma 12 cells in vitro, with enhanced cell growth, neurite extension, and cellular migration. Furthermore, an increased number of neurite protrusions were observed when the conduit was electrically stimulated. These results show that the electrically conductive PCLF-Graphene-CNT-MTAC nerve scaffolds presented here support the cellular behaviors that are critical for nerve regeneration, ultimately making this material an attractive candidate for regenerative medicine applications.

3D bioprinting of oligo(poly[ethylene glycol] fumarate) for bone and nerve tissue engineering.

3D bioprinting is a promising new tissue restoration technique that enables the precise deposition of cells and growth factors in order to more closely mimic the structure and function of native organs. In this study, we report the development of a new bioink using oligo(poly[ethylene glycol] fumarate) (OPF), a photo-crosslinkable, and biodegradable polymer, for 3D bioprinting. In addition to OPF, a small portion of gelatin was also incorporated into the bioink to make it bio-printable. After immersion in the cell medium, gelatin was eluted away to create a bioprinted scaffold of pure OPF. Excellent cell viability, spreading, and long-term proliferation of encapsulated cells was observed using both bone and nerve cells as examples. These results demonstrate that OPF bioink has great potential in future 3D bioprinting applications that aim to replicate complex, layered tissues, and/or organs.

2D phosphorene nanosheets, quantum dots, nanoribbons: synthesis and biomedical applications.

Phosphorene, also known as black phosphorus (BP), is a two-dimensional (2D) material that has gained significant attention in several areas of current research. Its unique properties such as outstanding surface activity, an adjustable bandgap width, favorable on/off current ratios, infrared-light responsiveness, good biocompatibility, and fast biodegradation differentiate this material from other two-dimensional materials. The application of BP in the biomedical field has been rapidly emerging over the past few years. This article aimed to provide a comprehensive review of the recent progress on the unique properties and extensive medical applications for BP in bone, nerve, skin, kidney, cancer, and biosensing related treatment. The details of applications of BP in these fields were summarized and discussed.

Black phosphorus incorporation modulates nanocomposite hydrogel properties and subsequent MC3T3 cell attachment, proliferation, and differentiation.

A promising strategy that emerged in tissue engineering is to incorporate two-dimensional (2D) materials into polymer scaffolds, producing materials with desirable mechanical properties and surface chemistries, which also display broad biocompatibility. Black phosphorus (BP) is a 2D material that has sparked recent scientific interest due to its unique structure and electrochemical characteristics. In this study, BP nanosheets (BPNSs) were incorporated into a cross-linkable oligo[poly(ethylene glycol) fumarate] (OPF) hydrogel to produce a new nanocomposite for bone regeneration. BPNSs exhibited a controllable degradation rate coupled with the release of phosphate in vitro. MTS assay results together with live/dead images confirmed that the introduction of BPNSs into OPF hydrogels enhanced MC3T3-E1 cell proliferation. Moreover, the morphology parameters indicated better attachments of cells in the BPNSs containing group. Immunofluorescence images as well as intercellular ALP and OCN activities showed that adding a certain amount of BPNSs to OPF hydrogel could greatly improve differentiation of pre-osteoblasts on the hydrogel. Additionally, embedding black phosphorous into a neutral polymer network helped to control its cytotoxicity, with optimal cell growth observed at BP concentrations as high as 500 ppm. These results reinforced that the supplementation of OPF with BPNSs can increase the osteogenic capacity of polymer scaffolds for use in bone tissue engineering.

Characteristics and comparative clinical outcomes of prisoner versus non-prisoner populations hospitalized with COVID-19.

Prisons in the United States have become a hotbed for spreading COVID-19 among incarcerated individuals. COVID-19 cases among prisoners are on the rise, with more than 143,000 confirmed cases to date. However, there is paucity of data addressing clinical outcomes and mortality in prisoners hospitalized with COVID-19. An observational study of all patients hospitalized with COVID-19 between March 10 and May 10, 2020 at two Henry Ford Health System hospitals in Michigan. Clinical outcomes were compared amongst hospitalized prisoners and non-prisoner patients. The primary outcomes were intubation rates, in-hospital mortality, and 30-day mortality. Multivariable logistic regression and Cox-regression models were used to investigate primary outcomes. Of the 706 hospitalized COVID-19 patients (mean age 66.7 ± 16.1 years, 57% males, and 44% black), 108 were prisoners and 598 were non-prisoners. Compared to non-prisoners, prisoners were more likely to present with fever, tachypnea, hypoxemia, and markedly elevated inflammatory markers. Prisoners were more commonly admitted to the intensive care unit (ICU) (26.9% vs. 18.7%), required vasopressors (24.1% vs. 9.9%), and intubated (25.0% vs. 15.2%). Prisoners had higher unadjusted inpatient mortality (29.6% vs. 20.1%) and 30-day mortality (34.3% vs. 24.6%). In the adjusted models, prisoner status was associated with higher in-hospital death (odds ratio, 2.32; 95% confidence interval (CI), 1.33 to 4.05) and 30-day mortality (hazard ratio, 2.00; 95% CI, 1.33 to 3.00). In this cohort of hospitalized COVID-19 patients, prisoner status was associated with more severe clinical presentation, higher rates of ICU admissions, vasopressors requirement, intubation, in-hospital mortality, and 30-day mortality.

Holographically defined nanoparticle placement in 3D colloidal crystals.

We demonstrate an optical interference-based photochemical method for the high-resolution localization of nanoparticles inside colloidal crystals or other porous structures. The method specifically relies on photoinduced inversion of the colloidal crystal surface charge to drive the localized deposition of charged gold nanoparticles. 4-Bromomethyl-3-nitrobenzoic acid (BNBA) was used as a photocleavable linker, and dansylamide was attached to BNBA to increase the absorption at 351 nm. Two-beam interference lithography was used for high-resolution optical patterning of the colloidal crystals; the resulting pattern was then decorated with functional nanoparticles. The periodicity of the pattern was 400 nm, and the width of the gold nanoparticle decorated region was approximately 200 nm. Our strategy of using photoswitching in a refractive-index-matched porous medium followed by the attachment of nanoparticles to the photoswitched region should be applicable to wide classes of charged nanoparticles.

Molecular dynamics simulation study of AG10 and tafamidis binding to the Val122Ile transthyretin variant.

Molecular dynamics (MD) simulations were used to investigate the binding of four ligands to the Val122Ile mutant of the protein transthyretin. Dissociation, misfolding, and subsequent aggregation of mutated transthyretin proteins are associated with the disease Familial Amyloidal Cardiomyopathy. The ligands investigated were the drug candidate AG10 and its decarboxy and N-methyl derivatives along with the drug tafamidis. These ligands bound to the receptor in two halogen binding pockets (HBP) designated AB and A'B'. Inter-ligand distances, solvent accessible surface areas, root mean squared deviation measurements, and extracted structures showed very little change in the AG10 ligands' conformations or locations within the HBP during the MD simulation. In addition, the AG10 ligands experienced stable, two-point interactions with the protein by forming hydrogen bonds with Ser-117 residues in both the AB and A'B' binding pockets and Lysine-15 residues found near the surface of the receptor. Distance measurements showed these H-bonds formed simultaneously during the MD simulation. Removal of the AG10 carboxylate functional group to form decarboxy-AG10 disrupted this two-point interaction causing the ligand in the AB pocket to undergo a conformational change during the MD simulation. Likewise, addition of a methyl group to the AG10 hydrazone functional group also disrupted the two-point interaction by decreasing hydrogen bonding interactions with the receptor. Finally, MD simulations showed that the tafamidis ligands experienced fewer hydrogen bonding interactions than AG10 with the protein receptor. The tafamidis ligand in pocket A'B' was also found to move deeper into the HBP during the MD simulation.

Phosphate functionalization and enzymatic calcium mineralization synergistically enhance oligo[poly(ethylene glycol) fumarate] hydrogel osteoconductivity for bone tissue engineering.

A current approach in bone tissue engineering is the implantation of polymeric scaffolds that promote osteoblast attachment and growth as well as biomineralization. One promising polymer is oligo[poly(ethylene glycol) fumarate] (OPF), a polyethylene glycol-based material that is biocompatible, injectable, and biodegradable, but in its native form does not support robust bone cell attachment or growth. To address this issue, this study evaluated the osteoconductivity of bis[02-(methacryloyloxy)ethyl] phosphate (BP) functionalized OPF hydrogels (OPF-BP) using MC3T3-E1 pre-osteoblast cells, both before and after enzymatic mineralization with a calcium solution. The inclusion of negatively charged functional groups allowed for the tailored uptake and release of calcium, while also altering the mechanical properties and surface topography of the hydrogel surface. In cell culture, OPF-BP hydrogels with 20 and 30% (w/w) BP optimized osteoblast attachment, proliferation, and differentiation after a 21-day in vitro period. In addition, the OPF-BP30 treatment, when mineralized with calcium, exhibited a 128% increase in osteocalcin expression when compared with the non-mineralized treatment. These findings suggest that phosphate functionalization and enzymatic calcium mineralization can act synergistically to enhance the osteoconductivity of OPF hydrogels, making this processed material an attractive candidate for bone tissue engineering applications.

Injectable Electrical Conductive and Phosphate Releasing Gel with Two-Dimensional Black Phosphorus and Carbon Nanotubes for Bone Tissue Engineering.

Injectable hydrogels have unique advantages for the repair of irregular tissue defects. In this study, we report a novel injectable carbon nanotube (CNT) and black phosphorus (BP) gel with enhanced mechanical strength, electrical conductivity, and continuous phosphate ion release for tissue engineering. The gel utilized biodegradable oligo(poly(ethylene glycol) fumarate) (OPF) polymer as the cross-linking matrix, with the addition of cross-linkable CNT-poly(ethylene glycol)-acrylate (CNTpega) to grant mechanical support and electric conductivity. Two-dimensional (2D) black phosphorus nanosheets were also infused to aid in tissue regeneration through the steady release of phosphate that results from environmental oxidation of phosphorus in situ. This newly developed BP-CNTpega-gel was found to enhance the adhesion, proliferation, and osteogenic differentiation of MC3T3 preosteoblast cells. With electric stimulation, the osteogenesis of preosteoblast cells was further enhanced with elevated expression of several key osteogenic pathway genes. As monitored with X-ray imaging, the BP-CNTpega-gel demonstrated excellent in situ gelation and cross-linking to fill femur defects, vertebral body cavities, and posterolateral spinal fusion sites in the rabbit. Together, these results indicate that this newly developed injectable BP-CNTpega-gel owns promising potential for future bone and broad types of tissue engineering applications.