Journal of Materials Chemistry B最新文献

Collective behavior has become a recent topic of investigation in systems chemistry. In pursuing this phenomenon, we present polymersome stomatocytes loaded with the enzyme urease, which show basic stigmergy-based communication and are capable of signal production, reception, and response by clustering with surface complementary binding partners. The collective behavior is transient and based on the widely known pH-sensitive non-covalent interactions between nitrilotriacetic acid (NTA) and histidine (His) moieties attached to the surface of urease-loaded and empty stomacytes, respectively. Upon the addition of the substrate urea, the urease stomatocytes are able to increase the environmental pH, allowing the NTA units to interact with the surface histidines on the complementary species, triggering the formation of transient clusters. The stomatocytes display a maximum clustering interaction at a pH between 6.3 and 7.3, and interparticle repulsive behavior outside this range. This leads to oscillating behavior, as the aggregates disassemble when the pH increases due to high local urease activity. After bulk pH conditions are restored, clustering can take place again. Within the detectable region of dynamic light scattering, individual stomatocytes can aggregate to agglomerates with 10 times their volume. Understanding and designing population behavior of active colloids can facilitate the execution of cooperative tasks, which are not feasible for individual colloids.

In this work, a series of cationic luminogens (designated as PSMP isomers) were developed based on the cyano positional isomerism strategy. The isomerism of the cyano substituent on the molecular skeleton can finely regulate the optical behaviour, the type of photoinduced reactive oxygen species (ROS), and mitochondria-targeted capability of isomers. Interestingly, PSMP-4, with the cyano group installed at an appropriate location, exhibits a special aggregation-induced emission effect and potent O₂˙⁻ generation efficacy through the type I photochemistry pathway. Notably, PSMP-4 can accumulate in mitochondria with high specificity. Taking advantage of its excellent photostability, PSMP-4 realizes in situ mitochondria imaging in a washing-free manner and sensitive response to the change of mitochondrial membrane potential. The integration of comprehensive photophysical properties and mitochondrial specificity enable PSMP-4 to successfully trigger the death of cancer cells through an efficient type I photodynamic therapy process both in vitro and in multicellular tumor spheroid models.

TiO₂ nanotubes (NTs) obtained via electrochemical anodization (EA) on conventionally machined titanium surfaces are reported to be promising for achieving mucointegration in dental implant therapy. Dental abutments, manufactured by selective laser melting (SLM), combined with thermal post-treatment, present a promising alternative to conventionally machined titanium. Based on an original protocol, this study aims to investigate how the characteristic microstructure of the α + β phases in post-heated SLM Ti6Al4V can influence the growth of NTs and the resulting physical and chemical surface properties. Ti6Al4V-SLM discs were fabricated, heat post-treated and mechanically polished. The samples were then subjected to EA under different voltage conditions (10, 20 and 30 V). The specimens’ surfaces were characterized at the same location, before NTs formation by electron backscatter diffraction (EBSD), and after by scanning electron microscopy (SEM). Then, roughness and wettability were studied to determine how EA affects surface properties compared to conventionally machined and polished titanium surfaces without NTs (reference). Surface reactivity was evaluated through chemical analysis and collagen binding capacities. The self-organized TiO₂ layer was developed on the α phase only and the β phase was preferentially dissolved. The characteristic dimensions of the nanotubes (diameter, length and wall thickness), measured by SEM image analysis, increased proportionally with the rise in voltage but were not affected by the crystallographic orientation of the underlying α grain. Micro-roughness was the same for nanotubular and reference surfaces. Wettability was improved, as was surface reactivity towards collagen, which may contribute to improved bioactivity of titanium surfaces in dentistry.

The abnormal pH in cell membranes can lead to disorder in membrane structure and permeability, and is also an important signal of cell cancer. The acidification of the cell membrane can lead to the disorder of cell lipid metabolism and lead to non-alcoholic fatty liver disease (NAFLD). However, fluorescent probes to detect the cell membrane pH have rarely been reported, let alone used to study NAFLD. For this, we developed a fluorescent probe (Mem-pH) that can firmly anchor the cell membrane based on lipophilic action and electrostatic action forces, and successfully detect membrane pH by fluorescence intensity. More importantly, the probe Mem-pH can quantify the pH of different kinds of cell membranes, further demonstrating that the pH of cancer cell membranes is lower than that of normal cell membranes. Furthermore, Mem-pH successfully differentiates and detects different degrees of NAFLD tissues, offering hope for timely diagnosis of NAFLD.

Treatment of local tumor recurrence and repair of the tissue defects after tumorectomy still remain clinical challenges. Currently, controlled release of therapeutic drugs is one of the widely used approaches to kill the residual and recurrent cancer cells, and stem cell-laden hydrogel scaffolds are promising candidates for soft tissue repair. However, hydrogel scaffolds with the bifunction of controlled release of therapeutic drugs for cancer therapy and loading stem cells for tissue repair are still not well established. In this study, we fabricated a biphasic hydrogel scaffold containing two types of core/shell filaments with drugs and stem cells loaded in the core part of these two filaments. Black phosphorus nanosheets were added to alginate (the shell layer) in the drug-loaded filament, endowing the scaffold with a photothermal effect under near infrared (NIR) laser irradiation. Moreover, NIR could trigger the drug release from the core/shell filaments to achieve photothermal-chemotherapy of cancer. Additionally, stem cells embedded in the core parts of the other filaments could maintain high cell viability due to the protection of the shell layer (pure alginate), which promoted soft tissue regeneration in vivo. Thus, the prepared biphasic scaffold with drug- and stem cell-laden core/shell filaments may be a potential candidate to fill the tissue defects after the surgical resection of tumors to kill the residual and recurrent cancer and repair the tissue defects.

A striking issue is the scarcity of imaging probes for the early diagnosis of Alzheimer's disease. For the development of Aβ biomarkers, a mitochondria targeting, de novo designed, aggregation-induced emission (AIE) probe Cou-AIE-TPP⁺ is constructed by engineering the aromatic coumarin framework into the bridge of electron donor–acceptor–donor tethered with a lipophilic cationic triphenylphosphonium (TPP⁺) group. The synthesized Cou-AIE-TPP⁺ probe exhibits biocompatibility, noncytotoxicity, and a huge Stokes shift (124 nm in PBS). Cou-AIE-TPP⁺ has respectable fluorescence augmentation inside the aggregated Aβ40 in comparison with monomeric Aβ40 with a high binding affinity (K_d = 83 nM) to Aβ40 aggregates, is capable of detecting the kinetics of amyloid aggregation, and is superior to the gold standard probe thioflavin T. Fluorescence lifetime and brightness are also augmented when the probe Cou-AIE-TPP⁺ binds with Aβ aggregates in PBS. Cou-AIE-TPP⁺ (λ_em 604 nm) selectively targets and images neuronal cell mitochondria, is useful to monitor mitochondrial morphology alteration and damage during Aβ40-induced neurotoxicity, recognizes neurotoxic Aβ fibrils, and is highly colocalized with thioflavin T, showing a decent Pearson correlation coefficient of 0.91 in the human neuroblastoma SH-SY5Y cell line. These findings indicate that the mitochondria targeting, de novo designed, functional AIE-based solvatofluorochromic Cou-AIE-TPP⁺ probe is a promising switch on biomarkers for fluorescence imaging of Aβ aggregates and to monitor mitochondrial morphology change and dysfunction during Aβ-induced neurotoxicity, which may offer imperative direction for the advancement of compelling AIE biomarkers for targeted early stage Aβ diagnosis in the future.

Most natural and synthetic polymers are promising materials for biomedical applications because of their biocompatibility, abundant availability, and biodegradability. Their properties can be tailored according to the intended application by fabricating composites with other polymers or ceramics. The incorporation of ceramic nanoparticles such as bioactive glass (BG) and hydroxyapatite aids in the improvement of mechanical and biological characteristics and alters the degradation kinetics of polymers. BG can be used in the form of nanoparticles, nanofibers, scaffolds, pastes, hydrogels, or coatings and is significantly employed in different applications. This biomaterial is highly preferred because of its excellent biocompatibility, bone-stimulating activity, and favourable mechanical and degradation characteristics. Different compositions of nano BG are incorporated into the polymer system and studied for positive results such as enhanced bioactivity, better cell adherence, and proliferation rate. This review summarizes the fabrication and the progress of natural/synthetic polymer-nano BG systems for biomedical applications such as drug delivery, wound healing, and tissue engineering. The challenges and the future perspectives of the composite system are also addressed.

Cancer, a pressing global health challenge, is characterized by its rapid onset and high mortality rates. Conventional treatment methods prove insufficient in achieving the desired therapeutic outcomes, underscoring the critical need to identify an effective and safe approach for cancer treatment. In this study, a copper-doped nanoparticle known as Cu²⁺-DOX@ZIF-90 is designed by incorporating copper(II) (Cu(II)) and encapsulating doxorubicin (DOX) within ZIF-90. Leveraging the elevated ATP levels in cancer cells relative to normal cells, Cu²⁺-DOX@ZIF-90 undergoes intracellular degradation, leading to the release of DOX and Cu(II). DOX, a traditional chemotherapy drug for clinical use, induces apoptosis in cancer cells. Cu(II) interacts with glutathione (GSH) to generate Cu(I), catalyzing H₂O₂ to produce ˙OH, thereby prompting apoptosis in cancer cells. Concurrently, the reduction of GSH enhances the therapeutic effect of chemodynamic therapy (CDT). Furthermore, Cu(II) triggers the aggregation of lipoylated mitochondrial proteins, leading to the formation of DLAT oligomers and ultimately promoting cuproptosis in cancer cells. In vivo experimental findings demonstrate that Cu²⁺-DOX@ZIF-90 does not cause damage to normal tissues and organs in tumor-bearing mice, with a notable tumor inhibition rate of 86.18%. This synergistic approach, combining chemotherapy, CDT, and cuproptosis, holds significant promise for the effective and safe treatment of cancer.

A series of fluorophores based on the (5-methyl-4-phenylthiazol-2-yl)-3-phenylacrylonitrile (MPTA) core were designed and synthesised for photocaging of amino acids and peptides. The photophysical characteristics of these compounds and their hybrids with biomolecules were thoroughly investigated through a joint experimental, spectral and computational approach. The photorelease ability of the obtained amino acids–MPTA and peptides–MPTA hybrids was studied under various conditions, including different UV irradiation wavelength and power, and solvents. The main reaction products were identified using high-performance liquid chromatography combined with high-resolution mass spectrometry. Photo uncaging kinetics was quantitatively studied using absorption spectroscopy. The mechanism of photorelease of amino acids and peptides was elucidated through quantum mechanical calculations, which were also used for the exploration of photophysical properties of the excited states, and photodissociation energetics quantification. Relationships between the structure of fluorophores and photodissociation characteristics were estimated, and fluorophores with the good uncaging characteristics (biomolecule photoreleasing yield, uncaging rate, and effectiveness) were identified. Cell viability assays using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide or MTT showed a low cytotoxicity of the hybrids. Confocal microscopy revealed the easy penetration of the hybrids into living cells and their selective accumulation in the endoplasmic reticulum, lipid droplets and mitochondria, depending on their chemical structure.

The aggregation of amyloid β peptide (Aβ) in the presence of elevated levels of transition-metal ions, e.g., Fe³⁺, Cu²⁺, Zn²⁺, is accountable for enhanced cellular toxicity in Alzheimer's disease. Many strategies are reported to inhibit either Cu²⁺, Zn²⁺, or Fe³⁺-induced Aβ fibrillation, focused on one metal. Herein, a taurine-containing adaptable metal sequestering peptide (AMSP) has been developed as the modulator of any of the cited metal-induced Aβ-aggregation in vitro. We designed the peptide conjugate comprising VFFA as a recognition motif and a taurine moiety coupled with a pendant chain of glutamic acid such that the –SO₃H groups of taurine lie nearby ¹³His and ¹⁴His of Aβ, and sequester such metal ions that construct the salt bridge preponderantly via¹³His–metal–¹⁴His composition as well as bridges with ⁶His of Aβ. We checked the modulation of fibrillar aggregates of Aβ in the presence of metal ions by monitoring the fibril accumulation using several biophysical methods. The results established that non-aggregating AMSP sequesters Zn²⁺ preferably, along with Fe³⁺ and Cu²⁺ ions from the metal–Aβ complex at the physiological condition, efficiently inhibiting Aβ aggregation. While such adaptable metal binders that can chelate various metals are new, AMSP inhibits aggregation through selective recognition and metal scavenging.