Macro-B12 and Unexpectedly High Levels of Plasma B12: A Critical Review.

A low total plasma vitamin B12 supports a clinical suspicion of B12 deficiency, while the interpretation of an unexpectedly normal/high level is marred by controversies. Here, we critically review current knowledge on B12 in blood plasma, including the presence of the so-called "macro-B12". The latter form is most often defined as the fraction of B12 that can be removed by precipitation with polyethylene glycol (PEG), a nonspecific procedure that also removes protein polymers and antibody-bound analytes. Plasma B12 includes B12 attached to transcobalamin and haptocorrin, and an increased concentration of one or both proteins almost always causes an elevation of B12. The total plasma B12 is measured by automated competitive binding assays, often incorrectly referred to as immunoassays, since the binding protein is intrinsic factor and not an antibody. An unexpectedly high level of B12 may be further explored using immunological measurements of haptocorrin and transcobalamin (optionally combined with e.g., size-exclusion chromatography). Nonspecific methods, such as PEG precipitation, are likely to give misleading results and cannot be recommended. Currently, the need for evaluation of a high B12 of unknown etiology is limited since other tests (such as measurements of methylmalonic acid) may better guide the diagnosis of B12 deficiency.

Macrophage Polarization Dynamics in Biomaterials: Implications for in Vitro Wound Healing.

The interaction between biomaterials and the immune system plays a pivotal role in determining the success or failure of implantable devices. Macrophages, as key orchestrators of immune responses, exhibit diverse reactions that influence tissue integration or lead to implant failure. This study focuses on unraveling the intricate relationship between macrophage phenotypes and biomaterials, specifically hydrogels, by employing THP-1 cells as a model. Through a comprehensive investigation using polysaccharide, polymer, and protein-based hydrogels, our research sheds light on how the properties of hydrogels influence macrophage polarization. Phenotypic observations, biochemical assays, surface marker expression, and gene expression profiles collectively demonstrate the differential macrophage polarization abilities of polysaccharide-, polymer-, and protein-based hydrogels. Moreover, our indirect coculture studies reveal that hydrogels fostering M2 polarization exhibit exceptional wound-healing capabilities. These findings highlight the crucial role of the hydrogel microenvironment in adjusting macrophage polarization, offering a fresh avenue for refining biomaterials to bolster advantageous immune responses and improve tissue integration. This research contributes valuable insights for designing biomaterials with tailored properties that can guide macrophage behavior, ultimately improving the overall success of implantable devices.

Biodegradable ferroelectric molecular crystal with large piezoelectric response.

Transient implantable piezoelectric materials are desirable for biosensing, drug delivery, tissue regeneration, and antimicrobial and tumor therapy. For use in the human body, they must show flexibility, biocompatibility, and biodegradability. These requirements are challenging for conventional inorganic piezoelectric oxides and piezoelectric polymers. We discovered high piezoelectricity in a molecular crystal HOCH2(CF2)3CH2OH [2,2,3,3,4,4-hexafluoropentane-1,5-diol (HFPD)] with a large piezoelectric coefficient d33 of ~138 picocoulombs per newton and piezoelectric voltage constant g33 of ~2450 × 10-3 volt-meters per newton under no poling conditions, which also exhibits good biocompatibility toward biological cells and desirable biodegradation and biosafety in physiological environments. HFPD can be composite with polyvinyl alcohol to form flexible piezoelectric films with a d33 of 34.3 picocoulombs per newton. Our material demonstrates the ability for molecular crystals to have attractive piezoelectric properties and should be of interest for applications in transient implantable electromechanical devices.

Liquid-liquid phase separation (LLPS) in DNA and chromatin systems from the perspective of colloid physical chemistry.

DNA is a highly charged polyelectrolyte and is prone to associative phase separation driven by the presence of multivalent cations, charged surfactants, proteins, polymers and colloids. The process of DNA phase separation induced by positively charged species is often called DNA condensation. Generally, it refers to either intramolecular DNA compaction (coil-globule transition) or intermolecular DNA aggregation with macroscopic phase separation, but the formation of a DNA liquid crystalline system is also displayed. This has traditionally been described by polyelectrolyte theory and qualitative (Flory-Huggins-based) polymer theory approaches. DNA in the cell nucleus is packed into chromatin wound around the histone octamer (a protein complex comprising two copies each of the four histone proteins H2A, H2B, H3 and H4) to form nucleosomes separated by linker DNA. During the last decade, the phenomenon of the formation of biomolecular condensates (dynamic droplets) by liquid-liquid phase separation (LLPS) has emerged as a generally important mechanism for the formation of membraneless organelles from proteins, nucleic acids and their complexes. DNA and chromatin droplet formation through LLPS has recently received much attention by in vitro as well as in vivo studies that established the importance of this for compartmentalisation in the cell nucleus. Here, we review DNA and chromatin LLPS from a general colloid physical chemistry perspective. We start with a general discussion of colloidal phase separation in aqueous solutions and review the original (pre-LLPS era) work on DNA (macroscopic) phase separation for simpler systems with DNA in the presence of multivalent cations and well-defined surfactants and colloids. Following that, we discuss and illustrate the similarities of such macroscopic phase separation with the general behaviour of LLPS droplet formation by associative phase separation for DNA-protein systems, including chromatin; we also note cases of segregative association. The review ends with a discussion of chromatin LLPS in vivo and its physiological significance.

Engineering Saccharomyces cerevisiae for targeted hydrolysis and fermentation of glucuronoxylan through CRISPR/Cas9 genome editing.

BACKGROUND: The abundance of glucuronoxylan (GX) in agricultural and forestry residual side streams positions it as a promising feedstock for microbial conversion into valuable compounds. By engineering strains of the widely employed cell factory Saccharomyces cerevisiae with the ability to directly hydrolyze and ferment GX polymers, we can avoid the need for harsh chemical pretreatments and costly enzymatic hydrolysis steps prior to fermentation. However, for an economically viable bioproduction process, the engineered strains must efficiently express and secrete enzymes that act in synergy to hydrolyze the targeted polymers. RESULTS: The aim of this study was to equip the xylose-fermenting S. cerevisiae strain CEN.PK XXX with xylanolytic enzymes targeting beechwood GX. Using a targeted enzyme approach, we matched hydrolytic enzyme activities to the chemical features of the GX substrate and determined that besides endo-1,4-ß-xylanase and ß-xylosidase activities, α-methyl-glucuronidase activity was of great importance for GX hydrolysis and yeast growth. We also created a library of strains expressing different combinations of enzymes, and screened for yeast strains that could express and secrete the enzymes and metabolize the GX hydrolysis products efficiently. While strains engineered with BmXyn11A xylanase and XylA ß-xylosidase could grow relatively well in beechwood GX, strains further engineered with Agu115 α-methyl-glucuronidase did not display an additional growth benefit, likely due to inefficient expression and secretion of this enzyme. Co-cultures of strains expressing complementary enzymes as well as external enzyme supplementation boosted yeast growth and ethanol fermentation of GX, and ethanol titers reached a maximum of 1.33 g L- 1 after 48 h under oxygen limited condition in bioreactor fermentations. CONCLUSION: This work underscored the importance of identifying an optimal enzyme combination for successful engineering of S. cerevisiae strains that can hydrolyze and assimilate GX. The enzymes must exhibit high and balanced activities, be compatible with the yeast's expression and secretion system, and the nature of the hydrolysis products must be such that they can be taken up and metabolized by the yeast. The engineered strains, particularly when co-cultivated, display robust growth and fermentation of GX, and represent a significant step forward towards a sustainable and cost-effective bioprocessing of GX-rich biomass. They also provide valuable insights for future strain and process development targets.

Chromolaena odorata layered-nitrile rubber polymer transdermal patch enhanced wound healing in vivo.

The objective is to investigate the healing efficacy of a Chromolaena odorata layered-nitrile rubber transdermal patch on excision wound healing in rats. Wounds were induced in Sprague-Dawley rats and were later treated as follows: wound A, the negative control, received no treatment (NC); wound B, the negative control with an empty nitrile rubber patch (NC-ERP); wound C, treated with a C. odorata layered-nitrile rubber patch (CO-NRP); and wound D, the positive control with Solcoseryl gel with a nitrile rubber patch (PC-SG-NRP). After 1, 3, 6, 10, and 14 days, the rats were sacrificed and analyzed for wound contraction, protein content, hexosamine, and uronic acid levels. Macroscopic observation showed enhanced wound healing in wounds treated with CO-NRP with a wound contraction percentage significantly higher (p<0.05) on days 6 and 10 compared to those treated with NC-ERP. Similarly, protein, hexosamine, and uronic acid contents were also significantly higher (p<0.05) in CO-NRP-treated wounds when compared with wounds treated with NC-ERP. Histological findings showed denser collagen deposition and faster granulation tissue formation in wounds treated with CO-NRP. From the results obtained, it is concluded that the C. odorata layered-nitrile rubber transdermal patch was effective in healing skin wounds.

Polymeric Nanohydrogel in Topical Drug Delivery System.

Nanohydrogels (NH) are biodegradable polymers that have been extensively studied and utilized for various biomedical applications. Drugs in a topical medication are absorbed via the skin and carried to the intended location, where they are metabolized and eliminated from the body. With a focus on their pertinent contemporary treatments, this review aims to give a complete overview of recent advances in the creation and application of polymer NH in biomedicine. We will explore the key features that have driven advances in nanotechnology and discuss the significance of nanohydrogel-based formulations as vehicles for delivering therapeutic agents topically. The review will also cover the latest findings and references from the literature to support the advancements in nanotechnological technology related to the preparation and application of NH. In addition, we will also discuss the unique properties and potential applications of NH as drug delivery systems (DDS) for skin applications, underscoring their potential for effective topical therapeutic delivery. The challenge lies in efficiently delivering drugs through the skin's barrier to specific areas with high control. Environmentally sensitive systems, like polymer-based NH, show promise in treating dermatological conditions. Polymers are pivotal in developing these drug delivery systems, with NH offering advantages such as versatile drug loading, controlled release, and enhanced skin penetration.

Nanoengineered Polymeric RNA Nanoparticles for Controlled Biodistribution and Efficient Targeted Cancer Therapy.

RNA nanotechnology, including rolling circle transcription (RCT), has gained increasing interest as a fascinating siRNA delivery nanoplatform for biostable and tumor-targetable RNA-based therapies. However, due to the lack of fine-tuning technologies for RNA nanostructures, the relationship between physicochemical properties and siRNA efficacy of polymeric siRNA nanoparticles (PRNs) with different sizes has not yet been fully elucidated. Herein, we scrutinized the effects of size/surface chemistry-tuned PRNs on the biological and physiological interactions with tumors. PRNs with adjusted size and surface properties were prepared using sequential engineering processes: RCT, condensation, and nanolayer deposition of functional biopolymers. Through the RCT process, nanoparticles of three sizes with a diameter of 50-200 nm were fabricated and terminated with three types of biopolymers: poly-l-lysine (PLL), poly-l-glutamate (PLG), and hyaluronic acid (HA) for different surface properties. Among the PRNs, HA-layered nanoparticles with a diameter of ∼200 nm exhibited the most effective systemic delivery, resulting in superior anticancer effects in an orthotopic breast tumor model due to the CD44 receptor targeting and optimized nanosized structure. Depending on the type of PRNs, the in vivo siRNA delivery with protein expression inhibition differed by up to approximately 20-fold. These findings indicate that the types of layered biopolymers and the PRNs size mediate efficient polymeric siRNA delivery to the targeted tumors, resulting in high RNAi-induced therapeutic efficacy. This RNA-nanotechnology-based size/surface editing can overcome the limitations of siRNA therapeutics and represents a potent built-in module method to design RNA therapeutics tailored for targeted cancer therapy.

Photo-crosslinkable polyester microneedles as sustained drug release systems toward hypertrophic scar treatment.

Burn injuries can result in a significant inflammatory response, often leading to hypertrophic scarring (HTS). Local drug therapies e.g. corticoid injections are advised to treat HTS, although they are invasive, operator-dependent, extremely painful and do not permit extended drug release. Polymer-based microneedle (MN) arrays can offer a viable alternative to standard care, while allowing for direct, painless dermal drug delivery with tailorable drug release profile. In the current study, we synthesized photo-crosslinkable, acrylate-endcapped urethane-based poly(ε-caprolactone) (AUP-PCL) toward the fabrication of MNs. Physico-chemical characterization (1H-NMR, evaluation of swelling, gel fraction) of the developed polymer was performed and confirmed successful acrylation of PCL-diol. Subsequently, AUP-PCL, and commercially available PCL-based microneedle arrays were fabricated for comparative evaluation of the constructs. Hydrocortisone was chosen as model drug. To enhance the drug release efficiency of the MNs, Brij®35, a nonionic surfactant was exploited. The thermal properties of the MNs were evaluated via differential scanning calorimetry. Compression testing of the arrays confirmed that the MNs stay intact upon applying a load of 7 N, which correlates to the standard dermal insertion force of MNs. The drug release profile of the arrays was evaluated, suggesting that the developed PCL arrays can offer efficient drug delivery for up to two days, while the AUP-PCL arrays can provide a release up to three weeks. Finally, the insertion of MN arrays into skin samples was performed, followed by histological analysis demonstrating the AUP-PCL MNs outperforming the PCL arrays upon providing pyramidical-shaped perforations through the epidermal layer of the skin.

AUP-PCL MN arrays provide long-term transdermal drug delivery of hydrocortisoneAUP-PCL-based MN arrays provide superior drug release profiles compared to PCL MNsEffective skin penetration AUP-PCL-based MNs on skin was achieved.

Application of MicroResp™ for quick and easy detection of plastic degradation by marine bacterial isolates.

Microplastic debris in the marine environment is a global problem. Biodegradable polymers are being developed as alternatives to petroleum-based plastics, and quick and easy methods for screening for bacterial strains that can degrade such polymers are needed. As a screening method, the clear zone method has been widely used but has technical difficulties such as plate preparation and interpretation of results. In this study, we adapted the MicroResp™ system to easily detect biodegradation activity of marine bacteria in a 3-day assay. Among the 6 bacterial strains tested, 3, 2 and 1 strain degraded poly (butylene succinate-co-adipate) (PBSA), poly (ε-caprolactone) (PCL) and poly (3-hydroxybutyrate-co-3-hydroxyhexanoate), respectively. Only one strain that showed degradation activity of PBSA and PCL in the MicroResp™ system was also positive in the clear zone assay on the respective emulsion plates. Our results show that the adapted MicroResp™ system can screen for bacterial strains that degrade plastic.

Hyaluronic acid/dextran-based polymeric micelles co-delivering ursolic acid and doxorubicin to mitochondria for potentiating chemotherapy in MDR cancer.

Cancer multidrug resistance (MDR) dramatically hindered the efficiency of standard chemotherapy. Mitochondria are highly involved in the occurrence and development of MDR; thus, inducing its malfunction will be an appealing strategy to treat MDR tumors. In this paper, a natural polysaccharides-based nanoplatform (TDTD@UA/HA micelles) with cell and mitochondria dual-targeting ability was facilely fabricated to co-deliver ursolic acid (UA) and doxorubicin (DOX) for combinatorial MDR therapy. TDTD@UA/HA micelles featured a spherical morphology, narrow size distribution (∼140 nm), as well as favorable drug co-loading capacity (DOX: 8.41 %, UA: 9.06 %). After hyaluronic acid (HA)-mediated endocytosis, the lysosomal hyaluronidase promoted the degradation of HA layer and then the positive triphenylphosphine groups were exposed, which significantly enhanced the mitochondria-accumulation of nano micelles. Subsequently, DOX and UA were specifically released into mitochondria under the trigger of endogenous reactive oxygen species (ROS), followed by severe mitochondrial destruction through generating ROS, exhausting mitochondrial membrane potential, and blocking energy supply, etc.; ultimately contributing to the susceptibility restoration of MCF-7/ADR cells to chemotherapeutic agents. Importantly, TDTD@UA/HA micelles performed potent anticancer efficacy without distinct toxicity on the MDR tumor-bearing nude mice model. Overall, the versatile nanomedicine represented a new therapeutic paradigm and held great promise in overcoming MDR-related cancer.

Investigation on Adaptability and Applicability of Polymer-Mediated Cell Surface Engineering by Ligation with Transglutaminase.

Polymer-mediated cell surface engineering can be a powerful tool to modify the cell's biological behavior, but a simple ligation strategy must be identified. This manuscript assessed the use of transglutamination as a versatile and adaptable approach for cell surface engineering in various cellular models relevant to biomedical applications. This enzymatic approach was evaluated for its feasibility and potential for conjugating polymers to diverse cell surfaces and its biological effects. Transglutaminase-mediated ligation was successfully performed at temperatures ranging from 4 to 37 °C in as quickly as 30 min, while maintaining biocompatibility and preserving cell viability. This approach was successfully applied to nine different cell surfaces (including adherent cells and suspension cells) by optimizing the enzyme source (guinea pig liver vs microbial), buffer compositions, and incubation conditions. Finally, polymer-mediated cell surface engineering using transglutaminase exhibited immunocamouflage abilities for endothelial cells, T cells, and red blood cells by preventing the recognition of cell surface proteins by antibodies. Employing transglutaminase in polymer-mediated cell surface engineering is a promising approach to maximize its application in cell therapy and other biomedical applications.

Cell-Material Interplay in Focal Adhesion Points.

The complex interplay between cells and materials is a key focus of this research, aiming to develop optimal scaffolds for regenerative medicine. The need for tissue regeneration underscores understanding cellular behavior on scaffolds, especially cell adhesion to polymer fibers forming focal adhesions. Key proteins, paxillin and vinculin, regulate cell signaling, migration, and mechanotransduction in response to the extracellular environment. This study utilizes advanced microscopy, specifically the AiryScan technique, along with advanced image analysis employing the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) cluster algorithm, to investigate protein distribution during osteoblast cell adhesion to polymer fibers and glass substrates. During cell attachment to both glass and polymer fibers, a noticeable shift in the local maxima of paxillin and vinculin signals is observed at the adhesion sites. The focal adhesion sites on polymer fibers are smaller and elliptical but exhibit higher protein density than on the typical glass surface. The characteristics of focal adhesions, influenced by paxillin and vinculin, such as size and density, can potentially reflect the strength and stability of cell adhesion. Efficient adhesion correlates with well-organized, larger focal adhesions characterized by increased accumulation of paxillin and vinculin. These findings offer promising implications for enhancing scaffold design, evaluating adhesion to various substrates, and refining cellular interactions in biomedical applications.

Efficient removal of Cr (VI) from coal gangue by indigenous bacteria-YZ1 bacteria: Adsorption mechanism and reduction characteristics of extracellular polymer.

The existence of heavy metals (especially Cr (VI)) in coal gangue has brought great safety risks to the environment. The indigenous bacteria (YZ1 bacteria) were separated and applied for removing Cr (VI) from the coal gangue, in which its tolerance to Cr (VI) was explored. The removal mechanism of Cr (VI) was investigated with pyrite in coal gangue, metabolite organic acids and extracellular polymer of YZ1 bacteria. The concentration of Cr (VI) could be stabilized around 0.012 mg/L by the treatment with YZ1 bacteria. The Cr (VI) tolerance of YZ1 bacteria reached 60 mg/L, and the removal efficiency of Cr (VI) was more than 95% by using YZ1 bacteria combined with pyrite. The organic acids had a certain reducing ability to Cr (VI) (removal efficiency of less than 10%). The extracellular polymers (EPS) were protective for the YZ1 bacteria resisting to Cr (VI). The polysaccharides and Humic-like substances in the soluble extracellular polymers (S-EPS) had strong adsorption and reduction effect on Cr (VI), in which the tryptophan and tyrosine proteins in the bound extracellular polymers (LB-EPS and TB-EPS) could effectively promote the reduction of Cr (VI). YZ1 bacteria could obviously reduce the damage of Cr (VI) from coal gangue to the environment.

Compartmentalization of galactan biosynthesis in mycobacteria.

Galactan polymer is a prominent component of the mycobacterial cell wall core. Its biogenesis starts at the cytoplasmic side of the plasma membrane by a build-up of the linker disaccharide [rhamnosyl (Rha) - N-acetyl-glucosaminyl (GlcNAc) phosphate] on the decaprenyl-phosphate carrier. This decaprenyl-P-P-GlcNAc-Rha intermediate is extended by two bifunctional galactosyl transferases, GlfT1 and GlfT2, and then it is translocated to the periplasmic space by an ABC transporter Wzm-Wzt. The cell wall core synthesis is finalized by the action of an array of arabinosyl transferases, mycolyl transferases, and ligases that catalyze an attachment of the arabinogalactan polymer to peptidoglycan through the linker region. Based on visualization of the GlfT2 enzyme fused with fluorescent tags it was proposed that galactan polymerization takes place in a specific compartment of the mycobacterial cell envelope, the intracellular membrane domain, representing pure plasma membrane free of cell wall components (previously denoted as the "PMf" domain), which localizes to the polar region of mycobacteria. In this work, we examined the activity of the galactan-producing cellular machine in the cell-wall containing cell envelope fraction and in the cell wall-free plasma membrane fraction prepared from Mycobacterium smegmatis by the enzyme assays using radioactively labeled substrate UDP-[14C]-galactose as a tracer. We found that despite a high abundance of GlfT2 in both of these fractions as confirmed by their thorough proteomic analyses, galactan is produced only in the reaction mixtures containing the cell wall components. Our findings open the discussion about the distribution of GlfT2 and the regulation of its activity in mycobacteria.

Key function of Kouleothrix in stable formation of filamentous aerobic granular sludge at low superficial gas velocity with polymeric substrates.

Forming and maintaining stable aerobic granular sludge (AGS) at a low superficial gas velocity (SGV) is challenging, particularly with polymeric substrates. This study cultivated filamentous aerobic granular sludge (FAGS) with filamentous Kouleothrix (Type 1851) at low SGV (0.15 cm/s) utilizing mixed acetate-soluble starch. Within approximately 260 days, notable increases in the relative abundance of Kouleothrix (from 4 % to 10 %) and Ca. Competibacter (from 1 % to 26 %) were observed through 16S rRNA gene analysis. Metagenomic analysis revealed increased expression of functional genes involved in volatile fatty acid (VFA) production (e.g., ackA and pta) and polyhydroxyalkanoate synthesis (e.g., phbB and phbC). Kouleothrix acted as a skeleton for bacterial attachment and was the key fermenting bacteria promoting granulation and maintaining granule stability. This study provides insight into the formation of FAGS with low-energy and non-VFA substrates.

Development of Aerosol Dry Powder Chemotherapeutic-Loaded Microparticles for the Treatment of Lung Cancer.

Lung cancer is the leading cause of cancer-related deaths worldwide, resulting in the highest mortality rates among both men and women with respect to all other types of cancer. Difficulties in treating lung cancer arise from late-stage diagnoses and tumor heterogeneity and current treatment involves a combination of chemotherapeutics, surgery, and radiation. Chemotherapeutics administered systemically can lead to undesirable side effects and severe off-site toxicity. For example, chronic administration of the chemotherapeutic doxorubicin (DOX) leads to cardiotoxicity, thereby limiting its long-term use. Systemic administration of the highly lipophilic molecule paclitaxel (PTX) is hindered by its water solubility, necessitating the use of solubilizing agents, which can induce side effects. Thus, in this investigation, formulations consisting of spray-dried microparticles (MP) containing DOX and PTX were produced to be administered as dry powder aerosols directly to the lungs. Acetalated dextran (Ac-Dex) was used as the polymer in these formulations, as it is a biocompatible and biodegradable polymer that exhibits pH-responsive degradation. Solid-state characterization revealed that DOX and PTX remained in solubility favoring amorphous states in the MP formulations and that both drugs remained thermally stable throughout the spray drying process. In vitro release studies demonstrated the pH sensitivity of the formulations due to the use of Ac-Dex, as well as the release of both therapeutics over the course of at least 48 h. In vitro aerosol dispersion studies demonstrated that both formulations exhibited suitable aerosol dispersion properties for deep lung delivery.

Breaking Iron Homeostasis: Iron Capturing Nanocomposites for Combating Bacterial Biofilm.

Given the scarcity of novel antibiotics, the eradication of bacterial biofilm infections poses formidable challenges. Upon bacterial infection, the host restricts Fe ions, which are crucial for bacterial growth and maintenance. Having coevolved with the host, bacteria developed adaptive pathways like the hemin-uptake system to avoid iron deficiency. Inspired by this, we propose a novel strategy, termed iron nutritional immunity therapy (INIT), utilizing Ga-CT@P nanocomposites constructed with gallium, copper-doped tetrakis (4-carboxyphenyl) porphyrin (TCPP) metal-organic framework, and polyamine-amine polymer dots, to target bacterial iron intakes and starve them. Owing to the similarity between iron/hemin and gallium/TCPP, gallium-incorporated porphyrin potentially deceives bacteria into uptaking gallium ions and concurrently extracts iron ions from the surrounding bacteria milieu through the porphyrin ring. This strategy orchestrates a "give and take" approach for Ga3+/Fe3+ exchange. Simultaneously, polymer dots can impede bacterial iron metabolism and serve as real-time fluorescent iron-sensing probes to continuously monitor dynamic iron restriction status. INIT based on Ga-CT@P nanocomposites induced long-term iron starvation, which affected iron-sulfur cluster biogenesis and carbohydrate metabolism, ultimately facilitating biofilm eradication and tissue regeneration. Therefore, this study presents an innovative antibacterial strategy from a nutritional perspective that sheds light on refractory bacterial infection treatment and its future clinical application.

Selective Intracellular Delivery of Antibodies in Cancer Cells with Nanocarriers Sensing Endo/Lysosomal Enzymatic Activity.

The differential enzymatic activity in the endo/lysosomes of particular cells could trigger targeted endosomal escape functions, enabling selective intracellular protein delivery. However, this strategy may be jeopardized due to protein degradation during endosomal trafficking. Herein, using custom made fluorescent probes to assess the endosomal activity of cathepsin B (CTSB) and protein degradation, we found that certain cancer cells with hyperacidified endosomes grant a spatiotemporal window where CTSB activity surpass protein digestion. This inspired the engineering of antibody-loaded polymeric nanocarriers having CTSB-activatable endosomal escape ability. The nanocarriers selectively escaped from the endo/lysosomes in the cells with high endosomal CTSB activity and delivered active antibodies to intracellular targets. This study provides a viable strategy for cell-specific protein delivery using stimuli-responsive nanocarriers with controlled endosomal escape.

The role of filamentous matrix molecules in shaping the architecture and emergent properties of bacterial biofilms.

Numerous bacteria naturally occur within spatially organised, multicellular communities called biofilms. Moreover, most bacterial infections proceed with biofilm formation, posing major challenges to human health. Within biofilms, bacterial cells are embedded in a primarily self-produced extracellular matrix, which is a defining feature of all biofilms. The biofilm matrix is a complex, viscous mixture primarily composed of polymeric substances such as polysaccharides, filamentous protein fibres, and extracellular DNA. The structured arrangement of the matrix bestows bacteria with beneficial emergent properties that are not displayed by planktonic cells, conferring protection against physical and chemical stresses, including antibiotic treatment. However, a lack of multi-scale information at the molecular level has prevented a better understanding of this matrix and its properties. Here, we review recent progress on the molecular characterisation of filamentous biofilm matrix components and their three-dimensional spatial organisation within biofilms.