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1.
Soft Matter ; 17(4): 863-869, 2021 Jan 28.
Article in English | MEDLINE | ID: mdl-33237084

ABSTRACT

The ability to control adhesion is critical in various technologies including wearable electronics, pressure sensitive adhesives, and robotic systems. Biomimetic fibrillar structures, random surface roughness, and chemical surface treatments have been employed to modify the adhesion energy of materials used in these applications. However, polymer thin film dewetting has not been investigated as a surface modification tool to control adhesion. In this work, polystyrene thin films are thermally annealed on a polydimethylsiloxane substrate, causing them to dewet and form stiff, microscopic asperities on the soft substrate. The size of the asperities increases with increasing pre-annealing film thickness. Adhesion is quantified by flat-punch normal indentation testing. The largest asperities exhibited a decrease in adhesion to below the sensitivity of the instrument. More interestingly, the surfaces covered with the smallest asperities displayed a pressure-dependent adhesive response. By increasing the normal compressive stress applied prior to separation, the total debonding energy increased monotonically on the smallest asperity-covered surfaces.

2.
Parasitology ; 148(12): 1490-1496, 2021 10.
Article in English | MEDLINE | ID: mdl-34193321

ABSTRACT

Environmental DNA (eDNA) surveying has potential to become a powerful tool for sustainable parasite control. As trematode parasites require an intermediate snail host that is often aquatic or amphibious to fulfil their lifecycle, water-based eDNA analyses can be used to screen habitats for the presence of snail hosts and identify trematode infection risk areas. The aim of this study was to identify climatic and environmental factors associated with the detection of Galba truncatula eDNA. Fourteen potential G. truncatula habitats on two farms were surveyed over a 9-month period, with eDNA detected using a filter capture, extraction and PCR protocol with data analysed using a generalized estimation equation. The probability of detecting G. truncatula eDNA increased in habitats where snails were visually detected, as temperature increased, and as water pH decreased (P < 0.05). Rainfall was positively associated with eDNA detection in watercourse habitats on farm A, but negatively associated with eDNA detection in watercourse habitats on farm B (P < 0.001), which may be explained by differences in watercourse gradient. This study is the first to identify factors associated with trematode intermediate snail host eDNA detection. These factors should be considered in standardized protocols to evaluate the results of future eDNA surveys.


Subject(s)
DNA, Environmental , Trematoda , Trematode Infections , Animals , Ecosystem , Trematoda/genetics , Water
3.
Soft Matter ; 16(27): 6230-6252, 2020 Jul 15.
Article in English | MEDLINE | ID: mdl-32567642

ABSTRACT

Mechanophores (MPs) are a class of stimuli-responsive materials that are of increasing interest to engineers due to their potential applications as stress sensors. These mechanically responsive molecules change color or become fluorescent upon application of a mechanical stimulus as they undergo a chemical reaction when a load is applied. By incorporating MPs such as spirolactam, spiropyran, or dianthracene into a material system, the real-time stress distribution of the matrix can be directly observed through a visual response, ideal for damage and failure sensing applications. A wide array of applications that require continuous structural health monitoring could benefit from MPs including flexible electronics, protective coatings, and polymer matrix composites. However, there are significant technical challenges preventing MP implementation in industry. Effective strategies to quantitatively calibrate the photo response of the MP with applied stress magnitudes must be developed. Additionally, environmental conditions, including temperature, humidity, and ultraviolet light exposure can potentially impact the performance of MPs. By addressing these limitations, engineers can work to move MPs from the synthetic chemistry bench to the field. This review aims to highlight recent progress in MP research, discuss barriers to implementation, and provide an outlook on the future of MPs, specifically focused on polymeric material systems. Although the focus is on engineering MPs for bulk materials, a brief overview of mechanochemistry will be discussed followed by methods for activation and quantification of MP photo response (concentrating specifically on fluorescently active species). Finally, current challenges and future directions in MP research will be addressed.

4.
Aust Crit Care ; 33(6): 538-545, 2020 11.
Article in English | MEDLINE | ID: mdl-32409251

ABSTRACT

Poor-quality patient handover leads to adverse patient outcomes. Consequently, handover has been identified as a national and international priority for preventing patient harm. Risks are exacerbated during transfers of trauma intensive care unit (ICU) patients to a ward because of the complexity of their injuries coupled with a de-escalation in care and monitoring. This study assessed current handover practices for ICU trauma patients, identifying barriers and facilitators to best practice handover. A multimethod design was used, including naturalistic observations of clinical handover of trauma patients transferred to a ward and semistructured interviews with both the ICU and ward nurses caring for the trauma patient. The study was conducted at an Australian metropolitan public adult teaching hospital ICU. Purposive maximal sampling of patient handover opportunities was sought. Recruitment continued until data saturation was reached using thematic analysis. Ten ICU and ward nurses were recruited, with 10 observations of handover and 20 interviews conducted. Observations of the handovers identified multiple issues, including deficits and discrepancies in the information communicated that could impact patient safety, variable handover processes, and poor patient and family involvement. Interviews elicited two major themes around the handover: practices and processes. Nurses identified that interruptions, time, and workload pressures presented barriers to handover, whilst teamwork, using a structured and systematic approach, preparation time for handover, and communication before transfer facilitated effective handover and transfer. Nurses suggested a structured tool to aid handover. This study identified clinically significant deficits and discrepancies in the information communicated to the ward nurses. Nurses identified that interruptions, time, and workload pressures presented barriers to effective handover. Teamwork where preparation and the handover event are prioritised over other activities is needed. A minimum data set for handover in conjunction with patients and family members is recommended.


Subject(s)
Critical Care Nursing , Nurses , Patient Handoff , Adult , Australia , Communication , Humans , Intensive Care Units
5.
Aust Crit Care ; 33(6): 488-496, 2020 11.
Article in English | MEDLINE | ID: mdl-32113735

ABSTRACT

BACKGROUND: Interventions to support psychological recovery after critical illness, including information provision via an intensive care unit (ICU) diary or discharge summary, have been widely adopted in some regions, albeit without strong empirical evidence. OBJECTIVE: The objective of this study was to examine the feasibility and acceptability, for patients, family members, and clinicians, of information provision via an ICU diary or discharge summary to support psychological recovery for critical illness survivors. METHODS: This was a pilot, partially randomised patient preference study in a mixed ICU in a tertiary hospital in Australia. Eligible patients were those in the ICU for >24 h and who were able to converse in English. Interventions were ICU diary or discharge summary compared with usual care. Feasibility was assessed throughout the study process, and acceptability assessed 3 and 6 months after hospital discharge, with data analysed descriptively and thematically. RESULTS: Sixty-one patients were recruited; 45 completed 3-month follow-up (74%), and 37 (61%), 6-month follow-up. Participants were medical (39%), surgical (30%), and trauma (31%) patients; aged 55 [interquartile range (IQR): 36-67] years; and stayed in the ICU for 7 [IQR: 3-13] days and hospital for 23 [IQR: 14-32] days. Within the partially randomised framework, 34 patients chose their intervention - four chose usual care, 10 ICU diary, and 20 discharge summary. The remaining 27 patients were randomised - nine usual care, 10 ICU diary, and seven discharge summary. The majority (>90%) considered each intervention helpful during recovery; however, a significant proportion of patients reported distress associated with reading the ICU diary (42%) or discharge summary (15%). Clinicians reported they were hesitant to make diary entries. CONCLUSIONS: When given a choice, more patients chose a discharge summary over the ICU diary or usual care. Participants considered both interventions acceptable. Given the reports of distress associated with information provision, clear empirical evidence is required to determine effectiveness, optimal timing, support needed, and for whom they should be used. CLINICAL TRIAL REGISTRATION NUMBER: ACTRN12615001079538.


Subject(s)
Critical Care , Patient Discharge , Critical Illness , Feasibility Studies , Humans , Intensive Care Units
6.
Aust Crit Care ; 33(5): 441-451, 2020 09.
Article in English | MEDLINE | ID: mdl-31757717

ABSTRACT

INTRODUCTION: Central venous access devices (CVADs) are a vital medical device for intensive care (ICU) patients; however, complications and failure are common, yet potentially prevented through effective dressings and securement. OBJECTIVES/AIMS: The objective of this study was to test the feasibility of a randomised controlled trial (RCT) comparing standard care with three dressing and securement products to prevent CVAD failure. Secondary aims included comparing dressing and securement products on CVAD failure, microbial colonisation, and intervention costs. METHODS: A single-centre pilot RCT of ICU adult patients requiring CVADs for >24 h were randomised to four groups: (i) sutures plus chlorhexidine gluconate (CHG) dressing (standard care); (ii) standard care plus tissue adhesive (TA); (iii) two sutureless stabilisation devices (SSD) plus CHG dressing; (iv) sutures, CHG disc plus integrated securement dressing (ISD). Descriptive statistics assessed feasibility. Incidence rates (IRs) of CVAD failure were reported, with group differences compared using the Fisher exact and log-rank tests. Cox regression explored univariable risks for failure. A substudy examined bacterial colonisation of catheter tips, dressings, and skin. Cost estimates of the intervention were compared. RESULTS: A total of 121 participants were randomised. Study feasibility was established with no withdrawal and moderate staff acceptability; however, recruitment was low at 12%. Overall CVAD failure was seen in 14 of 114 (12%) CVADs (19 per 1000 catheter-days); highest in the SSD group (IR: 27.3 per 1000 catheter-days [95% confidence interval {CI}: 11.4-65.6]), followed by the standard care group (IR: 22.3 per 1000 catheter-days [95% CI: 8.38-59.5]) and TA group (IR: 20.6 per 1000 catheter-days [95% CI: 6.66-64.0]), and lowest in the ISD group (IR: 8.8 per 1000 catheter-days [95% CI: 2.19-35.0]). The majority of complications (11/14, 79%) were suspected central line-associated bloodstream infection (CLABSI), of which only one was laboratory confirmed (standard care group). The cost per patient was lowest in the standard care group by an average difference of AUD $14. CONCLUSION(S): A large multisite RCT examining forms of securement and dressing is feasible. ISD is the highest priority to test further as it had the lowest failure rate. TRIAL REGISTRATION: ACTRN12615000667516 PROTOCOL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id = 368765.


Subject(s)
Catheter-Related Infections , Catheterization, Central Venous , Central Venous Catheters , Adult , Bandages , Catheter-Related Infections/prevention & control , Critical Care , Humans , Pilot Projects
7.
Soft Matter ; 15(31): 6375-6382, 2019 Aug 21.
Article in English | MEDLINE | ID: mdl-31305851

ABSTRACT

Understanding the adhesion of rigid thin films to compliant substrates is critical for the development and implementation of flexible electronic devices and wearable sensor technologies. Quantifying the strength of a film-substrate interface can be challenging due to the brittleness of glassy films which can greatly complicate sample preparation, handling, and testing. Here, a method for measuring the adhesion of glassy thin films to soft elastomeric substrates is explored that exploits an understanding of surface buckling instabilities, specifically the transition from wrinkling to delamination. The adhesion (given by the critical strain energy release rate (Gc)) for two model materials' interfaces is quantified by determining the critical delamination strain for thin glassy polymer films (polystyrene (PS) and poly(methyl methacrylate) (PMMA)) from an elastomeric substrate (poly(dimethyl siloxane) (PDMS)). By accounting for edge defects that greatly reduce the critical strain for delamination, reasonable adjusted Gc values of 21.0 ± 5.1 mJ m-2 and 32.2 ± 4.9 mJ m-2 are found for PS-PDMS and PMMA-PDMS interfaces, respectively. The utilization of this method to characterize film modulus and adhesion could be used as a facile measurement technique for more applied polymer thin film systems.

8.
Semin Respir Crit Care Med ; 40(6): 751-761, 2019 12.
Article in English | MEDLINE | ID: mdl-31659732

ABSTRACT

In cystic fibrosis (CF), absent or dysfunctional CF transmembrane conductance regulator (CFTR) on the surface of airway epithelial cells causes abnormal mucociliary clearance, leading to chronic endobronchial infection and inflammation, in turn resulting in life-shortening progressive obstructive lung disease and structural airway damage. Fortunately, CF-specific therapies have been developed that improve lung function and reduce pulmonary exacerbations, contributing significantly to improved survival over the past 4 decades. Therapies not originally developed for CF, such as bronchodilators and corticosteroids, are also widely used by people living with CF. Therapies to be reviewed in this article include mucolytics, airway surface liquid hydrators, anti-inflammatory medications, bronchodilators, inhaled and oral antibiotics, and airway clearance techniques. Determining which therapies to utilize can be challenging, as there is variable evidence for each treatment, differing national guidelines, few head-to-head studies, potential for drug-drug interactions, and synergistic toxicities, as well as issues with burden of care. In this review, we summarize the mechanism of action and available evidence, and compare national guidelines for each major medication used to treat the airway consequences of CFTR dysfunction.


Subject(s)
Cystic Fibrosis Transmembrane Conductance Regulator/genetics , Cystic Fibrosis/genetics , Cystic Fibrosis/therapy , Adrenal Cortex Hormones/therapeutic use , Anti-Inflammatory Agents/therapeutic use , Forced Expiratory Volume , Humans , Molecular Targeted Therapy , Mucociliary Clearance , Mutation , Physical Therapy Modalities , Practice Guidelines as Topic , Randomized Controlled Trials as Topic
9.
Soft Matter ; 13(43): 7930-7937, 2017 Nov 08.
Article in English | MEDLINE | ID: mdl-29034929

ABSTRACT

Compressing a thin, stiff film attached to a thick, compliant substrate can lead to a number of different modes of mechanical deformation depending upon the material properties of the system. In this article we explore direct transitions from surface wrinkling to buckle delamination, and provide a theoretical framework for understanding the conditions under which such transitions take place, as well as the resulting dimensions of the wrinkling-induced delamination. A key conclusion of this work is that the width of the delamination blister formed from a wrinkled film is relatively strain-independent, suggesting that delaminations can be used in such systems to measure the adhesion energy at the film-substrate interface. In addition, we demonstrate how the length and width of delaminations can be tailored through straightforward control of the substrate and film properties in the system, illustrating how wrinkling delaminations can be used for both thin film metrology and patterning applications.

10.
Soft Matter ; 13(38): 6761-6769, 2017 Oct 04.
Article in English | MEDLINE | ID: mdl-28819658

ABSTRACT

Material extrusion (ME) is a layer-by-layer additive manufacturing process that is now used in personal and commercial production where prototyping and customization are required. However, parts produced from ME frequently exhibit poor mechanical performance relative to those from traditional means; moreover, fundamental knowledge of the factors leading to development of inter-layer strength in this highly non-isothermal process is limited. In this work, we seek to understand the development of inter-layer weld strength from the perspective of polymer interdiffusion under conditions of rapidly changing mobility. Our framework centers around three interrelated components: in situ thermal measurements (via infrared imaging), temperature dependent molecular processes (via rheology), and mechanical testing (via mode III fracture). We develop the concept of an equivalent isothermal weld time and test its relationship to fracture energy. For the printing conditions studied the equivalent isothermal weld time for Tref = 230 °C ranged from 0.1 ms to 100 ms. The results of these analysis provide a basis for optimizing inter-layer strength, the limitations of the ME process, and guide development of new materials.

11.
Aust Crit Care ; 30(2): 59-66, 2017 Mar.
Article in English | MEDLINE | ID: mdl-27094380

ABSTRACT

BACKGROUND: Sleep disruption is common in intensive care unit (ICU) patients, with reports indicating reduced quality and quantity of sleep in many patients. There is growing evidence that sleep in this setting may be improved. AIM: To describe ICU patients' self-report assessment of sleep, examine the relationship between patients' self-reported sleep and their reported sleep by the bedside nurse, and describe the strategies suggested by patients to promote sleep. METHODS: An exploratory descriptive study was undertaken with communicative adult patients consecutively recruited in 2014-2015. Patients reported sleep using the Richards-Campbell Sleep Questionnaire (score range 0-100mm; higher score indicates better sleep quality), with nursing assessment of sleep documented across a five level ordinal variable. Patients were asked daily to describe strategies that helped or hindered their sleep. Ethical approval for the study was gained. Descriptive statistical analysis was performed [median (interquartile range)]; relationships were tested using Spearman's rank correlation and differences assessed using the Kruskal-Wallis test; p<0.05 was considered significant. RESULTS: Participants (n=151) were recruited [age: 60 (46-71) years; ICU length of stay 4 (2-9) days] with 356 self-reports of sleep. Median perceived sleep quality was 46 (26-65) mm. A moderate relationship existed between patients' self-assessment and nurses' assessment of sleep (Spearman's rank correlation coefficient 0.39-0.50; p<0.001). Strategies identified by patients to improve sleep included adequate pain relief and sedative medication, a peaceful and comfortable environment and physical interventions, e.g. clustering care, ear plugs. CONCLUSION: Patients reported on their sleep a median of 2 (1-3) days during their ICU stay, suggesting that routine use of self-report was feasible. These reports revealed low sleep quality. Patients reported multiple facilitators and barriers for sleep, with environmental and patient comfort factors being most common. Interventions that target these factors to improve patient sleep should be implemented.


Subject(s)
Intensive Care Units , Nursing Assessment , Self Report , Sleep Initiation and Maintenance Disorders/diagnosis , Aged , Female , Humans , Male , Middle Aged , Surveys and Questionnaires
13.
Langmuir ; 30(35): 10626-36, 2014 Sep 09.
Article in English | MEDLINE | ID: mdl-25127556

ABSTRACT

A carefully controlled, custom-built adhesion testing device was developed which allows a precise, short dwell time on the order of milliseconds to be applied during a contact adhesion experiment. The dwell time dependence of the adhesive strength of crosslinked poly(dimethylsiloxane) (PDMS) in contact with glass and uncrosslinked styrene butadiene rubber (SBR) in contact with glass and with itself was tested with a spherical probe in a confined Johnson-Kendall-Roberts (JKR) geometry. Analysis of the contact images revealed several unique separation mechanisms which are dependent on dwell time and interfacial properties. PDMS-glass interfaces show essentially no dependence of adhesion on the dwell time while the adhesive strength and separation mechanisms of SBR interfaces are shown to vary drastically for dwell times ranging from 40 to 10,000 ms. This influence of dwell time is particularly pronounced for polymer-polymer (SBR-SBR) interfaces. Observations of cavitation due to trapped air pockets in the center of the contact at very short contact times illustrate a transition between a defect-controlled debonding and an interface-controlled debonding which has not been previously reported.

14.
Chem Asian J ; 19(1): e202300850, 2024 Jan 02.
Article in English | MEDLINE | ID: mdl-37938167

ABSTRACT

Force-responsive molecules that produce fluorescent moieties under stress provide a means for stress-sensing and material damage assessment. In this work, we report a mechanophore based on Diels-Alder adduct TAD-An of 4,4'-(4,4'-diphenylmethylene)-bis-(1,2,4-triazoline-3,5-dione) and initiator-substituted anthracene that can undergo retro-Diels-Alder (rDA) reaction by pulsed ultrasonication and compressive activation in bulk materials. The influence of having C-N versus C-C bonds at the sites of bond scission is elucidated by comparing the relative mechanical strength of TAD-An to another Diels-Alder adduct MAL-An obtained from maleimide and anthracene. The susceptibility to undergo rDa reaction correlates well with bond energy, such that C-N bond containing TAD-An degrades faster C-C bond containing MAL-An because C-N bond is weaker than C-C bond. Specifically, the results from polymer degradation kinetics under pulsed ultrasonication shows that polymer containing TAD-An has a rate constant of 1.59×10-5  min-1 , while MAL-An (C-C bond) has a rate constant of 1.40×10-5  min-1 . Incorporation of TAD-An in a crosslinked polymer network demonstrates the feasibility to utilize TAD-An as an alternative force-responsive probe to visualize mechanical damage where fluorescence can be "turned-on" due to force-accelerated retro-Diels-Alder reaction.

15.
J Colloid Interface Sci ; 645: 502-512, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37159992

ABSTRACT

Elastomeric materials combining multiple properties within a single composite are highly desired in applications including biomaterials interfaces, actuators, and soft robotics. High spatial resolution is required to impart different properties across the composite for the intended application, but many techniques used to prepare these composites rely on multistep and complex methods. There is a need for the development of simple and efficient platforms to design layered composite materials. Here, we report the synthesis of horizontally- and vertically-patterned composites consisting of PDMS-based polymerized high internal phase emulsion (polyHIPE) porous elastomers and PDMS/PEG hydrogels. Composites with defined interfaces that were mechanically robust were prepared, and rheological analysis of the polyHIPE and hydrogel layers showed storage moduli values of âˆ¼ 35 kPa and 45 kPa respectively. The compressive Young's Modulus and maximum strain of the polyHIPEs were dependent on the thiol to ene ratio in the formulation and obtained values ranging from 6 to 25 kPa and 50-65% respectively. The mechanical properties, total porosity of the polyHIPE, and swelling ratio of the hydrogel were unaffected by the patterning technique compared to non-patterned controls. PolyHIPE-hydrogel composite materials having up to 7-different horizontally pattered layers could be prepared that could expand and contract up hydration and drying.

16.
Adv Mater ; 35(5): e2207337, 2023 Feb.
Article in English | MEDLINE | ID: mdl-36281806

ABSTRACT

Control of adhesion is important in a host of applications including soft robotics, pick-and-place manufacturing, wearable devices, and transfer printing. While there are adhesive systems with discrete switchability between states of high and low adhesion, achieving continuously variable adhesion strength remains a challenge. In this work, a pressure-tunable adhesive (PTA) that is based on the self-assembly of stiff microscale asperities on an elastomeric substrate is presented. It is demonstrated that the adhesion strength of the PTA increases with the applied compressive preload due to the unique contact formation mechanism caused by the asperities. Additionally, a contact mechanics model is developed to explain the resulting trends. For a specific PTA design, the critical pull-off force can be increased from 0.4 to 30 mN by increasing the applied preload from 1 to 30 mN. Finally, the applicability of precision control of adhesion strength is demonstrated by utilizing the PTA for pick-and-place material handling. The approach in pressure-tunable adhesive design based on self-assembly of asperities presents a scalable and versatile approach that is applicable to a variety of material systems having different mechanical or surface properties.

17.
Ann Am Thorac Soc ; 20(1): 75-82, 2023 01.
Article in English | MEDLINE | ID: mdl-36044723

ABSTRACT

Rationale: Pulmonary exacerbation (PEx) events contribute to lung function decline in people with cystic fibrosis (CF). CF Foundation PEx guidelines note that a short course of systemic corticosteroids may offer benefit without contributing to long-term adverse effects. However, insufficient evidence exists to recommend systemic corticosteroids for PEx treatment. Objectives: To determine if systemic corticosteroids for the treatment of in-hospital pediatric PEx are associated with improved clinical outcomes compared with treatment without systemic corticosteroids. Methods: We conducted a retrospective cohort study using the CF Foundation Patient Registry-Pediatric Health Information System linked database. People with CF were included if hospitalized for a PEx between 2006 and 2018 and were 6-21 years of age. Time to next PEx was assessed by Cox proportional hazards regression. Lung function outcomes were assessed by linear mixed-effect modeling and generalized estimating equations. To address confounding by indication, inverse probability treatment weighting was used. Results: A total of 3,471 people with CF contributed 9,787 PEx for analysis. Systemic corticosteroids were used in 15% of all PEx. In our primary analysis, systemic corticosteroids were not associated with better pre- to post-PEx percent predicted forced expiratory volume in 1 second responses (mean difference, -0.36; 95% confidence interval [CI], -1.14, 0.42; P = 0.4) or a higher odds of returning to lung function baseline (odds ratio, 0.97; 95% CI, 0.84-1.12; P = 0.7) but were associated with a reduced chance of future PEx requiring intravenous antibiotics (hazard ratio, 0.91; 95% CI, 0.85-0.96; P = 0.002). When restricting the analysis to one PEx per person, lung function outcomes remained no different among PEx treated with or without systemic corticosteroids, but, in contrast to our primary analysis, the use of systemic corticosteroids was no longer associated with a reduced chance of having a future PEx requiring intravenous antibiotics (hazard ratio, 0.96; 95% CI, 0.86, 1.07; P = 0.42). Conclusions: Systemic corticosteroid treatment for in-hospital pediatric PEx was not associated with improved lung function outcomes. Prospective trials are needed to better evaluate the risks and benefits of systemic corticosteroid use for PEx treatment in children with CF.


Subject(s)
Cystic Fibrosis , Humans , Child , Cystic Fibrosis/complications , Cystic Fibrosis/drug therapy , Prospective Studies , Retrospective Studies , Disease Progression , Forced Expiratory Volume , Adrenal Cortex Hormones/therapeutic use , Anti-Bacterial Agents/therapeutic use
18.
ACS Appl Mater Interfaces ; 15(8): 11360-11368, 2023 Mar 01.
Article in English | MEDLINE | ID: mdl-36787222

ABSTRACT

Control over the surface chemistry of elastomers such as polydimethylsiloxane (PDMS) is important for many applications. However, achieving nanostructured chemical control on amorphous material interfaces below the length scale of substrate heterogeneity is not straightforward, and can be particularly difficult to decouple from changes in network structure that are required for certain applications (e.g., variation of elastic modulus for cell culture). We have recently reported a new method for precisely structured surface functionalization of PDMS and other soft materials, which displays high densities of ligands directly on the material surface, maximizing steric accessibility. Here, we systematically examine structural factors in the PDMS components (e.g., base and cross-linker structures) that impact efficiency of the interfacial reaction that leads to surface functionalization. Applying this understanding, we demonstrate routes for generating equivalent nanometer-scale functional patterns on PDMS with elastic moduli from 0.013 to 1.4 MPa, establishing a foundation for use in applications such as cell culture.

19.
Mater Today Adv ; 192023 Aug.
Article in English | MEDLINE | ID: mdl-37691883

ABSTRACT

Recent advances in biomaterials and 3D printing/culture methods enable various tissue-engineered tumor models. However, it is still challenging to achieve native tumor-like characteristics due to lower cell density than native tissues and prolonged culture duration for maturation. Here, we report a new method to create tumoroids with a mechanically active tumor-stroma interface at extremely high cell density. This method, named "inkjet-printed morphogenesis" (iPM) of the tumor-stroma interface, is based on a hypothesis that cellular contractile force can significantly remodel the cell-laden polymer matrix to form densely-packed tissue-like constructs. Thus, differential cell-derived compaction of tumor cells and cancer-associated fibroblasts (CAFs) can be used to build a mechanically active tumor-stroma interface. In this methods, two kinds of bioinks are prepared, in which tumor cells and CAFs are suspended respectively in the mixture of collagen and poly (N-isopropyl acrylamide-co-methyl methacrylate) solution. These two cellular inks are inkjet-printed in multi-line or multi-layer patterns. As a result of cell-derived compaction, the resulting structure forms tumoroids with mechanically active tumor-stroma interface at extremely high cell density. We further test our working hypothesis that the morphogenesis can be controlled by manipulating the force balance between cellular contractile force and matrix stiffness. Furthermore, this new concept of "morphogenetic printing" is demonstrated to create more complex structures beyond current 3D bioprinting techniques.

20.
J Extracell Vesicles ; 12(1): e12298, 2023 01.
Article in English | MEDLINE | ID: mdl-36604533

ABSTRACT

Over the last decade, research interest in defining how extracellular vesicles (EVs) shape cross-species communication has grown rapidly. Parasitic helminths, worm species found in the phyla Nematoda and Platyhelminthes, are well-recognised manipulators of host immune function and physiology. Emerging evidence supports a role for helminth-derived EVs in these processes and highlights EVs as an important participant in cross-phylum communication. While the mammalian EV field is guided by a community-agreed framework for studying EVs derived from model organisms or cell systems [e.g., Minimal Information for Studies of Extracellular Vesicles (MISEV)], the helminth community requires a supplementary set of principles due to the additional challenges that accompany working with such divergent organisms. These challenges include, but are not limited to, generating sufficient quantities of EVs for descriptive or functional studies, defining pan-helminth EV markers, genetically modifying these organisms, and identifying rigorous methodologies for in vitro and in vivo studies. Here, we outline best practices for those investigating the biology of helminth-derived EVs to complement the MISEV guidelines. We summarise community-agreed standards for studying EVs derived from this broad set of non-model organisms, raise awareness of issues associated with helminth EVs and provide future perspectives for how progress in the field will be achieved.


Subject(s)
Extracellular Vesicles , Helminths , Animals , Humans , Extracellular Vesicles/physiology , Reproducibility of Results , Mammals
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