Peptide-based hydrogels represent promising systems for the sustained release of different types of drugs, ranging from small molecules to biologicals. Aiming at subcutaneous injection, which is a ...desirable parenteral administration route, especially for biologicals, we herein focus on physically crosslinked systems possessing thixotropic behaviour. The purpose of this study was to evaluate the in vitro and in vivo properties of hydrogels based on the amphipathic hexapeptide H-FQFQFK-NH2, which served as the lead sequence. Upon doubling the length of this peptide, the dodecapeptide H-FQFQFKFQFQFK-NH2 gave a significant improvement in terms of in vivo stability of the hydrogel post-injection, as monitored by nuclear SPECT/CT imaging. This increased hydrogel stability also led to a more prolonged in vivo release of encapsulated peptide cargoes. Even though no direct link with the mechanical properties of the hydrogels before injection could be made, an important effect of the subcutaneous medium was noticed on the rheological properties of the hydrogels in post in vivo injection measurements. The results were validated in vivo for a therapeutically relevant analgesic peptide using the hot-plate test as an acute pain model. It was confirmed that elongation of the hydrogelator sequence induced more extended antinociceptive effects. Altogether, this simple structural modification of the hydrogelating peptide could provide a basis for reaching longer durations of action upon use of these soft biomaterials.
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•Doubling of the hydrogelator length provides a more extended drug release in mice.•Physicochemical properties of a loaded drug influence the release profile from peptide-based hydrogels.•Pre-injection and post-injection mechanical properties of peptide-based hydrogels can differ substantially.•Extension of the hydrogelator length extends the in vivo analgesic effect of encapsulated peptide-based opioid ligands.
Solid-state sensing platforms are desirable for the development of reusable sensors to promote public health measures such as testing for drinking water contamination. A bioinspired metal–organic ...framework (MOF)-based material has been developed by imitating metal–protein interactions in biological systems to attain high sensitivity and selectivity to Pb2+ through fluorescence sensing. A zirconium terephthalate-type framework (also known as NH2-UiO-66) was modified with both gold nanoparticles and thiol-functionalized carbon dots to give HS-C/Au(x)/UiO-66 composites with different Au content (x) and were subsequently adapted into films that show extraordinary sensitivity to Pb2+. The HS-C/Au(1.4)/UiO-66 film that consists of 1.4 wt % Au shows a quenching response with the limit of detection of 80 parts per trillion and sustained performance for five cycles. Moreover, the fluorescence response of the HS-C/Au(x)/UiO-66 film to Pb2+ can be reversed from emission quenching to enrichment of fluorescence by increasing the Au content. The performance of the HS-C/Au(x)/UiO-66 film as a solid-state sensor demonstrates its potential for application in reusable sensing devices to ensure public safety from Pb2+ contamination in drinking water.
Herein, we demonstrate a method for the functionalization of cubic phase lipid nanoparticles (cubosomes) with a series of magnetite (Fe3O4), copper oxide (Cu2O), and silver (Ag) nanocrystals, with ...prospective applications across a wide range of fields, including antimicrobial treatments. The resulting cubosomes are characterized using small-angle X-ray scattering and dynamic light scattering, demonstrating the retention of a typical cubic phase structure and particle size following nanocrystal encapsulation at concentrations up to 20% w/w. Cryogenic transmission electron microscopy reveals significant loading and association of each nanocrystal type with both monoolein- and phytantriol-based cubosomes. The antibiotic potential of these hybrid nanoparticles is demonstrated for the first time; cubosomes with embedded silver nanocrystals display a high level of antimicrobial activity against both Gram-positive and Gram-negative bacteria, with observed minimum inhibitory concentration values ranging from 15.6–250 μg/mL. Lastly, total internal reflection fluorescence microscopy is used to visualize cubosome–bacteria interactions, suggesting the involvement of particle interactions as a delivery mechanism.
An improved vaccine is urgently needed to replace the now more than 100-year-old Bacillus Calmette–Guérin (BCG) vaccine against tuberculosis (TB) disease, which represents a significant burden on ...global public health. Mycolic acid, or cord factor trehalose 6,6′ dimycolate (TDM), a lipid component abundant in the cell wall of the pathogen Mycobacterium tuberculosis (MTB), has been shown to have strong immunostimulatory activity but remains underexplored due to its high toxicity and poor solubility. Herein, we employed a novel strategy to encapsulate TDM within a cubosome lipid nanocarrier as a potential subunit nanovaccine candidate against TB. This strategy not only increased the solubility and reduced the toxicity of TDM but also elicited a protective immune response to control MTB growth in macrophages. Both pre-treatment and concurrent treatment of the TDM encapsulated in lipid monoolein (MO) cubosomes (MO–TDM) (1 mol %) induced a strong proinflammatory cytokine response in MTB-infected macrophages, due to epigenetic changes at the promoters of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) in comparison to the untreated control. Furthermore, treatment with MO–TDM (1 mol %) cubosomes significantly improved antigen processing and presentation capabilities of MTB-infected macrophages to CD4 T cells. The ability of MO–TDM (1 mol %) cubosomes to induce a robust innate and adaptive response in vitro was further supported by a mathematical modeling study predicting the vaccine efficacy in vivo. Overall, these results indicate a strong immunostimulatory effect of TDM when delivered through the lipid nanocarrier, suggesting its potential as a novel TB vaccine.
The invaluable health, economic and social impacts of vaccination are hard to exaggerate. The ability to stabilize vaccines is urgently required for their equitable distribution without the ...dependence on the ‘cold-chain’ logistics. Herein, for the first time we report biomimetic-mineralization of live-viral vaccines using metal-organic frameworks (MOFs) to enhance their storage stability from days to months. Applying ZIF-8 and aluminium fumarate (Alfum), the Newcastle Disease Virus (NDV) V4 strain and Influenza A WSN strain were encapsulated with remarkable retention of their viral titre. The ZIF-8@NDV, ZIF-8@WSN and Alfum@WSN composites were validated for live-virus recovery using a tissue culture infectious dose (TCID50) assay. With the objective of long-term stabilization, we developed a novel, trehalose (T) and skim milk (SM) stabilized, freeze-dried MOF@Vaccine composite, ZIF-8@NDV+T/SM. The thermal stability of this composite was investigated and compared with the control NDV and non-encapsulated, freeze-dried NDV+T/SM composite at 4 °C, RT, and 37 °C over a period of 12 weeks. We demonstrate the fragility of the control NDV vaccine which lost all viability at RT and 37°C by 12 and 4 weeks, respectively. Comparing the freeze-dried counterparts, the MOF encapsulated ZIF-8@NDV+T/SM demonstrated significant enhancement in stability of the NDV+T/SM composite especially at RT and 37 °C upto 12 weeks.
Vaccination is undoubtedly one of the most effective medical interventions, saving millions of lives each year. However, the requirement of ‘cold-chain’ logistics is a major impediment to widespread immunization. Live viral vaccines (LVVs) are widely used vaccine types with proven efficacy and low cost. Nonetheless, their complex composition increases their susceptability to thermal stress. Several LVV thermostabilization approaches have been investigated, including their complex engineering and the facile addition of stabilizers. Still, the lack of a universal approach urgently requires finding a stabilization technique especially when additives alone may not be sufficient. Herein, we demonstrate MOF biomimetic-mineralization technology to encapsulate LVVs developing an optimised composite which significantly preserves vaccines without refrigeration for extended periods of time.
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The development of simple, cost‐effective, rapid, and quantitative diagnostic tools remains critical to monitor infectious COVID‐19 disease. Although numerous diagnostic platforms, including rapid ...antigen tests, are developed and used, they suffer from limited accuracy, especially when tested with asymptomatic patients. Here, a unique approach to fabricate a nanochannel‐based electrochemical biosensor that can detect the entire virion instead of virus fragments, is demonstrated. The sensing platform has uniform nanoscale channels created by the convective assembly of polystyrene (PS) beads on gold electrodes. The PS beads are then functionalized with bioreceptors while the gold surface is endowed with anti‐fouling properties. When added to the biosensor, SARS‐CoV‐2 virus particles block the nanochannels by specific binding to the bioreceptors. The nanochannel blockage hinders the diffusion of a redox probe; and thus, allows quantification of the viral load by measuring the changes in the oxidation current before and after virus incubation. The biosensor shows a low limit of detection of ≈1.0 viral particle mL−1 with a wide detection range up to 108 particles mL−1 in cell culture media. Moreover, the biosensor is able to differentiate saliva samples with SARS‐CoV‐2 from those without, demonstrating the potential of this technology for translation into a point‐of‐care biosensor product.
An electrochemical biosensor was constructed by convectively assembling polystyrene (PS) beads on a gold electrode to detect SAR‐Cov‐2 virus via partial nanochannel blockage by virus particles. Nanochannel blockage hinders the diffusion of a redox probe and causes attenuation of oxidation current, allowing quantification of the viral load by measuring the changes in oxidation currents before and after virus incubation.
There are increasing numbers of reports describing human vaginal tissue composition in women with and without pelvic organ prolapse with conflicting results. The aim of this study was to compare ...ovine and human posterior vaginal tissue in terms of histological and biochemical tissue composition and to assess passive biomechanical properties of ovine vagina to further characterise this animal model for pelvic organ prolapse research.
Vaginal tissue was collected from ovariectomised sheep (n = 6) and from postmenopausal women (n = 7) from the proximal, middle and distal thirds. Tissue histology was analyzed using Masson's Trichrome staining; total collagen was quantified by hydroxyproline assays, collagen III/I+III ratios by delayed reduction SDS PAGE, glycosaminoglycans by dimethylmethylene blue assay, and elastic tissue associated proteins (ETAP) by amino acid analysis. Young's modulus, maximum stress/strain, and permanent strain following cyclic loading were determined in ovine vagina.
Both sheep and human vaginal tissue showed comparable tissue composition. Ovine vaginal tissue showed significantly higher total collagen and glycosaminoglycan values (p<0.05) nearest the cervix. No significant differences were found along the length of the human vagina for collagen, GAG or ETAP content. The proximal region was the stiffest (Young's modulus, p<0.05), strongest (maximum stress, p<0.05) compared to distal region, and most elastic (permanent strain).
Sheep tissue composition and mechanical properties showed regional differences along the postmenopausal vaginal wall not apparent in human vagina, although the absolute content of proteins were similar. Knowledge of this baseline variation in the composition and mechanical properties of the vaginal wall will assist future studies using sheep as a model for vaginal surgery.
Throughout the past decades, amphipathic peptide-based hydrogels have proven to be promising materials for biomedical applications. Amphipathic peptides are known to adopt β-sheet configurations that ...self-assemble into fibers that then interact to form a hydrogel network. A fundamental understanding of how the peptide sequence alters the structural properties of the hydrogels would allow for a more rational design of novel peptides for a variety of biomedical applications in the future. Therefore, the current work investigates how changing the type of amino acid, the amphipathic pattern, and the peptide length affects the secondary structure, fiber characteristics, and stiffness of peptide-based hydrogels. Hereto, seven amphipathic peptides of different sequence and length, four of which have not been previously reported, based on and including the hexapeptide H-Phe-Gln-Phe-Gln-Phe-Lys-NH2, are synthesized and thoroughly characterized by circular dichroism (CD), Fourier Transform Infrared (FTIR) spectroscopy, Wide Angle X-ray Scattering (WAXS), Small Angle X-ray Scattering (SAXS), Transmission Electron Microscopy (TEM), and Thioflavin T (ThT) fibrillization assays. The results show that a high amount of regularly spaced β-sheets, a high amount of fibers, and fiber bundling contribute to the stiffness of the hydrogel. Furthermore, a study of the time-dependent fibril formation process reveals complex transient dynamics. The peptide strands structure through an intermediate helical state prior to β-sheet formation, which is found to be concentration- and time-dependent.
Throughout the past decades, amphipathic peptide-based hydrogels have proven to be promising materials for biomedical applications. Amphipathic peptides are known to adopt β-sheet configurations that ...self-assemble into fibers that then interact to form a hydrogel network. A fundamental understanding of how the peptide sequence alters the structural properties of the hydrogels would allow for a more rational design of novel peptides for a variety of biomedical applications in the future. Therefore, the current work investigates how changing the type of amino acid, the amphipathic pattern, and the peptide length affects the secondary structure, fiber characteristics, and stiffness of peptide-based hydrogels. Hereto, seven amphipathic peptides of different sequence and length, four of which have not been previously reported, based on and including the hexapeptide H-Phe-Gln-Phe-Gln-Phe-Lys-NH
, are synthesized and thoroughly characterized by circular dichroism (CD), Fourier Transform Infrared (FTIR) spectroscopy, Wide Angle X-ray Scattering (WAXS), Small Angle X-ray Scattering (SAXS), Transmission Electron Microscopy (TEM), and Thioflavin T (ThT) fibrillization assays. The results show that a high amount of regularly spaced β-sheets, a high amount of fibers, and fiber bundling contribute to the stiffness of the hydrogel. Furthermore, a study of the time-dependent fibril formation process reveals complex transient dynamics. The peptide strands structure through an intermediate helical state prior to β-sheet formation, which is found to be concentration- and time-dependent.
To undertake a comprehensive analysis of the biochemical tissue composition and passive biomechanical properties of ovine vagina and relate this to the histo-architecture at different reproductive ...stages as part of the establishment of a large preclinical animal model for evaluating regenerative medicine approaches for surgical treatment of pelvic organ prolapse.
Vaginal tissue was collected from virgin (n = 3), parous (n = 6) and pregnant sheep (n = 6; mean gestation; 132 d; term = 145 d). Tissue histology was analyzed using H+E and Masson's Trichrome staining. Biochemical analysis of the extracellular matrix proteins used a hydroxyproline assay to quantify total collagen, SDS PAGE to measure collagen III/I+III ratios, dimethylmethylene blue to quantify glycosaminoglycans and amino acid analysis to quantify elastin. Uniaxial tensiometry was used to determine the Young's modulus, maximum stress and strain, and permanent strain following cyclic loading.
Vaginal tissue of virgin sheep had the lowest total collagen content and permanent strain. Parous tissue had the highest total collagen and lowest elastin content with concomitant high maximum stress. In contrast, pregnant sheep had the highest elastin and lowest collagen contents, and thickest smooth muscle layer, which was associated with low maximum stress and poor dimensional recovery following repetitive loading.
Pregnant ovine vagina was the most extensible, but the weakest tissue, whereas parous and virgin tissues were strong and elastic. Pregnancy had the greatest impact on tissue composition and biomechanical properties, compatible with significant tissue remodeling as demonstrated in other species. Biochemical changes in tissue protein composition coincide with these altered biomechanical properties.
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