Journal of Materials Chemistry B最新文献

Bleeding and wound infection are two significant potential risks to life and health. While antibacterial hemostatic hydrogels can meet the requirements for hemostasis and the prevention of wound infections, the inclusion of antibacterial agents inevitably complicates the regulation of interactions between components, making it difficult to synergistically control the mechanical and antibacterial properties of the hydrogels, which limits the overall hydrogel performance. In this study, we propose the use of linear poly(N-isopropylacrylamide) (L-P-(C₆H₁₅N⁺)) with an antibacterial quaternary ammonium end-group for preparing hydrogels, rather than conventionally adding antibacterial agents. An injectable, highly antibacterial and wet-adhesive double-network hemostatic hydrogel was constructed using L-P-(C₆H₁₅N⁺), gelatin (G), and hyaluronic acid (HA). The comprehensive properties of the hydrogel could be adjusted through changing the molecular weight of the L-P-(C₆H₁₅N⁺) and the end-group effects. The G/HA/L-P-(C₆H₁₅N⁺) hydrogel demonstrated a gel time of 12.2–14 s, an adhesion strength of 26.9 ± 2.0 kPa and a burst pressure of 264 ± 20 mmHg. It also exhibited strong antibacterial activity against E. coli (93 ± 2.7%) and S. aureus (97 ± 3.2%), with satisfactory biocompatibility. Additionally, the hydrogel demonstrated good blood clotting ability in vitro and achieved rapid hemostasis (<15 s) in vivo. This work offers a simple and efficient strategy to fabricate high-performance smart antibacterial hemostatic hydrogels.

Ti alloys are sensitive to fretting wear, which leads to early failure of their implants. Wear is a major factor in determining the long-term clinical performance. This work explored the increase of wear resistance in antibacterial Ti–Cu alloys, by incorporating biocompatible nano-ZrO₂ using laser metal deposition (LMD). The content of the reinforcing nano-ZrO₂ played a crucial role in performance. There was good densification quality for ≤3 wt%. The densification quality declined and there were macrocracks for ≥5 wt%. Both the prior β grains and the α grains initially decreased in size followed by coarsening as the ZrO₂ content increased, with the minimum at 3 wt%. The yield strength increased with increasing ZrO₂ content, and the elastic modulus increased from 5 wt%. The wear rate decreased initially and then increased with increasing ZrO₂ contents, reaching the lowest wear rate at 3 wt%. The corrosion resistance in body fluid was a minimum between 3 and 5 wt%, with less or more leading to a decrease in corrosion resistance. In vitro antibacterial tests and MC3T3-E1 cell culture assays indicated that ZrO₂ contents of up to 10 wt% achieved good antibacterial effects while maintaining good biocompatibility. The comprehensive test results allowed screening and optimization of the processability and wear-related performance. 3 wt% ZrO₂ contents provided the best overall performance. The mechanisms for various content bioactive nano-ZrO₂ integrated for wear resistance, in vitro antibacterial and biological properties were explored. This work aimed to understand how ZrO₂ concentrations influenced the overall performance and to identify the optimal content for wear resistance and related biofunctionality.

A graphical abstract is available for this content

The pathophysiology associated with type 2 diabetes mellitus (T2DM) includes insulin resistance, increased oxidative stress, a pro-inflammatory macrophage population, and dysfunction of pancreatic β cells in the islets of Langerhans, along with hepato- and nephro-toxicity. In this study, an injectable glucose-responsive hydrogel (Diabogel) was developed using alginate and 3-aminophenyl boronic acid to deliver modified glucagon-like peptide-1, insulinoma cell-derived extracellular vesicles, and telmisartan. Diabogel demonstrated cytocompatibility, decreased reactive oxygen species, enhanced insulin synthesis, and improved glucose uptake in vitro. In a high-fat diet/streptozotocin-induced murine model of T2DM, Diabogel lowered blood glucose levels, maintained body weight, and increased insulin expression. Furthermore, it promoted an anti-inflammatory microenvironment in the pancreas by regulating macrophage phenotype and the expression of NF-κB, supported cellular proliferation, and restored the pancreatic islets. In addition, Diabogel treatment significantly lowered the serum levels of pro-inflammatory cytokines and enhanced anti-inflammatory cytokines. Interestingly, Diabogel treatment also lowered diabetes-associated hepato- and nephro-toxicity. Taken together, Diabogel may serve as a potential approach for the treatment of T2DM, regulating blood glucose levels, restoring pancreatic β cell function, and reducing hepatic and renal toxicities.

N-Alkyl-galactonamides, which are small synthetic molecules derived from galactose, self-assemble to give fibrous hydrogels. These molecules are biocompatible and, in a previous study, the cell culture of human neural stem cells was performed for 7 days on a gel of N-heptyl-D-galactonamide. With the objective of broadening the scope of these molecules as scaffolds for cell culture, in the present study, the culture of primary human dermal fibroblasts has been carried out on N-nonyl-D-galactonamide hydrogels. These supramolecular fibrillar hydrogels have a sufficient mechanical strength to withstand cell culture (≈50 kPa) and they are resistant enough on the long term to carry out the cell culture over at least 3 weeks. In contrast to N-heptyl-D-galactonamide, N-nonyl-D-galactonamide is insoluble in the culture medium. It avoids its dissolution at each renewal of the culture medium. The molecule is only slowly eliminated by other mechanisms (1/3rd in 3 weeks), which did not impair the cell culture on a monthly scale. The hydrogel's microstructure and how the cells organize on this scaffold have been studied using electron and two-photon microscopies. The gel is made of a quite homogeneous network with a width of ≈180 nm and hundreds of micrometer long fibers, except at the surface where a dense mat of heterogeneous fibers is formed. We focused on methods able to colocalize the cells and the gel fibers. Many cell clusters have elongated and multidirectionnal shapes, guided by the fibers. Chains of single cells are also found following the fibers from one cluster to another. N-Nonyl-D-galactonamide fibers, which have the advantage of not being autofluorescent, do not mask the fluorescence of cells. But interestingly, they give a strong second harmonic generation (SHG) signal, due to their well-organized lamellar structure. We also made a special effort to visualize the penetration of cells within the depth of the hydrogels, in 3D, notably by sectioning the hydrogels, despite their softness. It was found that most of the cells stayed at the surface, but several cells grew within the supramolecular fiber network between 50 and 100 μm depth.

A graphical abstract is available for this content

The integration of second near-infrared (NIR-II) fluorescence imaging and photothermal therapy (PTT) achieved precise and efficient tumor treatment. BODIPY, a promising fluorescent dye, is widely used in biological fluorescence imaging due to its excellent optical properties and chemical stability. However, the excitation wavelengths of BODIPY typically range from 530 nm to 650 nm within the visible spectrum, which significantly limits tissue penetration. In this work, a self-assembled nanoparticle (BODIPY₄–PEG NP) was fabricated with a BODIPY-conjugated oligomer (BODIPY₄) bearing a hydrophilic polyethylene glycol (PEG) chain. BODIPY₄–PEG NPs exhibit excellent NIR-II emission, with a maximum fluorescence emission peak of 1123 nm. The outstanding imaging performance of BODIPY₄–PEG NPs has been evaluated in the imaging of lymph nodes and the vascular system in mice, demonstrating excellent spatial resolution. Based on the excellent imaging performance and photothermal conversion efficiency (35%) of the BODIPY₄–PEG NPs, they can be further utilized in NIR-II imaging-guided photothermal therapy. In a 4T1 tumor-bearing mouse model, BODIPY₄–PEG NPs exhibited strong fluorescence under 980 nm laser irradiation and successfully induced heat generation to eliminate the tumor. To summarize, BODIPY₄–PEG NPs contribute to the ongoing progress in the field of NIR-II fluorescence imaging-guided PTT.

Aptamers are short single strand nucleic acid sequences that exhibit high-affinity molecular recognition towards non nucleic acid targets. They offer many benefits over antibodies, but still suffer from variable affinities and stability issues. Recently, aptamers have been incorporated as functional recognition agents into molecularly imprinted polymers, a competing recognition technology, to create hybrid materials, AptaMIPs, that exhibit the benefits of both classes. Specifically, this process can increase target affinity while preventing aptamer degradation. For the first time, using a lysozyme aptamer as an exemplar, we have undertaken a systematic and fundamental study to identify the optimal number and location of polymer connection points on an aptameric sequence for boosting AptaMIP target affinity and selectivity creating high affinity recognition elements. Clear patterns have emerged showing “fixing” throughout the molecule is required, but only in particular regions of the sequence. The results suggest that conformationally flexible regions within the polymer-bound aptameric sequence are detrimental to strong target binding, supporting the hypothesis that a successful imprinting process must lock the aptamer into its ideal binding conformation to achieve observable marked improvement in recognition. Conversely, too much flexibility in the embedded oligo (demonstrated through limited binding points) leads to poor performance. These findings offer a clear direction for development of aptamer–polymer hybrids. We also demonstrate the effectiveness of the developed materials in sensitive detection of the template using surface plasmon resonance, through improved quality of the recognition element.

DNA circuits have been widely used in the regulation of biomolecules and biochemical reactions due to their excellent controllability and responsiveness, but their regulation of intracellular organelles is still limited. Herein, we develop a photo-triggered mitochondrial regulation strategy based on a hybridization chain reaction (HCR) in living cells. In the design, the initial DNA hairpin is locked by a photocleavable group, and the assembling DNA hairpin pairs are tagged with triphenylphosphine for mitochondrial binding. Upon irradiation with UV light, the initiator hairpin is cleaved to trigger the HCR between triphenylphosphine-labeled hairpin pairs, followed by forming a long double-stranded DNA polymer for several of the mitochondria regulations in living cells. Our results demonstrate that mitochondrial regulation based on the HCR can successfully repair ROS stressed cells. Together, this work provides a new strategy for the spatiotemporally controlled regulation of intracellular mitochondria, exhibiting great potential in precision therapy.

Nanozymes, nanomaterials with enzyme-like characteristics which exhibit lower cost, easier synthesis and functionalization, and better stability compared with natural enzymes, have been widely developed for biosensing, disease therapy and environmental governance. However, the lack of catalytic efficiency of nanozymes compared to natural enzymes makes it difficult for them to completely replace natural enzymes to achieve higher sensitivity and lower detection limits in biosensing. Herein, magnetism-controlled technology was used to form a nanozyme array consisting of stacked Fe₃O₄/Au NPs at the bottom of the microchannel as a spatially confined microreactor for the catalytic reaction. By enhancing the mass transfer process of the substrate towards nanozymes mediated by the corresponding V-structure, a higher local concentration of the substrate and more efficient utilization of active sites of nanozymes were achieved to increase the catalytic efficiency (k_cat/K_M) of the nanozyme array consisting of Fe₃O₄/Au NPs by 95.2%, which was two orders of magnitude higher than that of the open reactor. Based on this, a colorimetric method on an integrated microfluidic platform was proposed for sensitive biosensing of Salmonella typhimurium. The entire detection could be completed within 30 minutes, yielding a linear range from 10² to 10⁷ CFU mL⁻¹ and a detection limit as low as 5.6 CFU mL⁻¹.