Enhancing the Carrier Transport in Monolayer MoS2 through Interlayer Coupling with 2D Covalent Organic Frameworks.

The coupling of different 2D materials (2DMs) to form van der Waals heterostructures (vdWHs) is a powerful strategy for adjusting the electronic properties of 2D semiconductors, for applications in opto-electronics and quantum computing. 2D molybdenum disulfide (MoS2 ) represents an archetypical semiconducting, monolayer thick versatile platform for the generation of hybrid vdWH with tunable charge transport characteristics through its interfacing with molecules and assemblies thereof. However, the physisorption of (macro)molecules on 2D MoS2 yields hybrids possessing a limited thermal stability, thereby jeopardizing their technological applications. Herein, the rational design and optimized synthesis of 2D covalent organic frameworks (2D-COFs) for the generation of MoS2 /2D-COF vdWHs exhibiting strong interlayer coupling effects are reported. The high crystallinity of the 2D-COF films makes it possible to engineer an ultrastable periodic doping effect on MoS2 , boosting devices' field-effect mobility at room temperature. Such a performance increase can be attributed to the synergistic effect of the efficient interfacial electron transfer process and the pronounced suppression of MoS2 's lattice vibration. This proof-of-concept work validates an unprecedented approach for the efficient modulation of the electronic properties of 2D transition metal dichalcogenides toward high-performance (opto)electronics for CMOS digital circuits.

Repression of autocrine pheromone signaling leads to fusaric acid over-production.

Fusaric acid (FA), a picolinic acid derivative, is a natural substance produced by a wide variety of fungal plant pathogens belonging to the Fusarium genus. As a metabolite, fusaric acid exerts several biological activities including metal chelation, electrolyte leakage, repression of ATP synthesis, and direct toxicity on plants, animals and bacteria. Prior studies on the structure of fusaric acid revealed a co-crystal dimeric adduct between FA and 9,10-dehydrofusaric acid. During an ongoing search for signaling genes differentially regulating FA production in the fungal pathogen Fusarium oxysporum (Fo), we found that mutants lacking pheromone expression have an increased production of FA compared to the wild type strain. Noteworthy, crystallographic analysis of FA extracted from Fo culture supernatants showed that crystals are formed by a dimeric form of two FA molecules (1:1 molar stoichiometry). Overall, our results suggest that pheromone signaling in Fo is required to regulate the synthesis of fusaric acid.

Interaction between Engineered Pluronic Silica Nanoparticles and Bacterial Biofilms: Elucidating the Role of Nanoparticle Surface Chemistry and EPS Matrix.

Nanoparticles (NPs) are considered a promising tool in the context of biofilm control. Many studies have shown that different types of NPs can interfere with the bacterial metabolism and cellular membranes, thus making them potential antibacterial agents; however, fundamental understanding is still lacking on the exact mechanisms involved in these actions. The development of NP-based approaches for effective biofilm control also requires a thorough understanding of how the chosen nanoparticles will interact with the biofilm itself, and in particular with the biofilm self-produced extracellular polymeric matrix (EPS). This work aims to provide advances in the understanding of the interaction between engineered fluorescent pluronic silica (PluS) nanoparticles and bacterial biofilms, with a main focus on the role of the EPS matrix in the accumulation and diffusion of the particles in the biofilm. It is demonstrated that particle surface chemistry has a key role in the different lateral distribution and specific affinity to the biofilm matrix components. The results presented in this study contribute to our understanding of biofilm-NP interactions and promote the principle of the rational design of smart nanoparticles as an important tool for antibiofilm technology.

Phytochemistry and Biological Activity of Medicinal Plants in Wound Healing: An Overview of Current Research.

Wound healing is a complicated process, and the effective management of wounds is a major challenge. Natural herbal remedies have now become fundamental for the management of skin disorders and the treatment of skin infections due to the side effects of modern medicine and lower price for herbal products. The aim of the present study is to summarize the most recent in vitro, in vivo, and clinical studies on major herbal preparations, their phytochemical constituents, and new formulations for wound management. Research reveals that several herbal medicaments have marked activity in the management of wounds and that this activity is ascribed to flavonoids, alkaloids, saponins, and phenolic compounds. These phytochemicals can act at different stages of the process by means of various mechanisms, including anti-inflammatory, antimicrobial, antioxidant, collagen synthesis stimulating, cell proliferation, and angiogenic effects. The application of natural compounds using nanotechnology systems may provide significant improvement in the efficacy of wound treatments. Increasing the clinical use of these therapies would require safety assessment in clinical trials.

Competitiveness during Dual-Species Biofilm Formation of Fusarium oxysporum and Candida albicans and a Novel Treatment Strategy.

During an infection, a single or multispecies biofilm can develop. Infections caused by non-dermatophyte molds, such as Fusarium spp. and yeasts, such as Candida spp., are particularly difficult to treat due to the formation of a mixed biofilm of the two species. Fusarium oxysporum is responsible for approximately 20% of human fusariosis, while Candida albicans is responsible for superficial mucosal and dermal infections and for disseminated bloodstream infections with a mortality rate above 40%. This study aims to investigate the interactions between C. albicans and F. oxysporum dual-species biofilm, considering variable formation conditions. Further, the ability of the WMR peptide, a modified version of myxinidin, to eradicate the mixed biofilm when used alone or in combination with fluconazole (FLC) was tested, and the efficacy of the combination of WMR and FLC at low doses was assessed, as well as its effect on the expression of some biofilm-related adhesin and hyphal regulatory genes. Finally, in order to confirm our findings in vivo and explore the synergistic effect of the two drugs, we utilized the Galleria mellonella infection model. We concluded that C. albicans negatively affects F. oxysporum growth in mixed biofilms. Combinatorial treatment by WMR and FLC significantly reduced the biomass and viability of both species in mature mixed biofilms, and these effects coincided with the reduced expression of biofilm-related genes in both fungi. Our results were confirmed in vivo since the synergistic antifungal activity of WMR and FLC increased the survival of infected larvae and reduced tissue invasion. These findings highlight the importance of drug combinations as an alternative treatment for C. albicans and F. oxysporum mixed biofilms.

Impairment of the cellulose degradation machinery enhances Fusarium oxysporum virulence but limits its reproductive fitness.

Fungal pathogens grow in the apoplastic space, in constant contact with the plant cell wall (CW) that hinders microbe progression while representing a source of nutrients. Although numerous fungal CW modifying proteins have been identified, their role during host colonization remains underexplored. Here, we show that the root-infecting plant pathogen Fusarium oxysporum (Fo) does not require its complete arsenal of cellulases to infect the host plant. Quite the opposite: Fo mutants impaired in cellulose degradation become hypervirulent by enhancing the secretion of virulence factors. On the other hand, the reduction in cellulase activity had a severe negative effect on saprophytic growth and microconidia production during the final stages of the Fo infection cycle. These findings enhance our understanding of the function of plant CW degradation on the outcome of host-microbe interactions and reveal an unexpected role of cellulose degradation in a pathogen's reproductive success.

A robust vertical nanoscaffold for recyclable, paintable, and flexible light-emitting devices.

Organic light-emitting devices are key components for emerging opto- and nanoelectronics applications including health monitoring and smart displays. Here, we report a foldable inverted polymer light-emitting diode (iPLED) based on a self-suspended asymmetrical vertical nanoscaffold replacing the conventional sandwich-like structured LEDs. Our empty vertical-yet-open nanoscaffold exhibits excellent mechanical robustness, proven by unaltered leakage current when applying 1000 cycles of 40-kilopascal pressure loading/unloading, sonication, and folding, with the corresponding iPLEDs displaying a brightness as high as 2300 candela per square meter. By using photolithography and brush painting, arbitrary emitting patterns can be generated via a noninvasive and mask-free process with individual pixel resolution of 10 µm. Our vertical nanoscaffold iPLED can be supported on flexible polyimide foils and be recycled multiple times by washing and refilling with a different conjugated polymer capable of emitting light of different color. This technology combines the traits required for the next generation of high-resolution flexible displays and multifunctional optoelectronics.

Selection of Endophytic Beauveria bassiana as a Dual Biocontrol Agent of Tomato Pathogens and Pests.

Endophytic fungi (EF) can enhance both plant growth and defense barriers against pests and pathogens, contributing to the reduction of chemical pesticides and fertilizers use in agriculture. Beauveria bassiana is an entomopathogenic fungus showing endophytism in several crops, often associated with a good capacity to limit the development of pests and disease agents. However, the diversity of the protective efficacy and plant response to different strains can be remarkable and needs to be carefully assessed for the successful and predictable use of these beneficial microorganisms. This study aims to select B. bassiana strains able to colonize tomato plants as endophytes as well as to control two important disease agents, Botrytis cinerea and Alternaria alternata, and the pest aphid, Macrosiphum euphorbiae. Nine wild-type isolates and one commercial strain were screened for endophytism, then further characterized for plant-growth promotion plus inhibition of disease development and pest infestation. Four isolates proved to have a good control activity against the biotic stressors tested, but only Bb716 was also able to promote plant growth. This work provides a simple workflow for the selection of beneficial EF, paving the way towards more effective use of B. bassiana in Integrate Pest Management (IPM) of tomato.

Synthesis and self-assembly of curcumin-modified amphiphilic polymeric micelles with antibacterial activity.

BACKGROUND: The ubiquitous nature of bacterial biofilms combined with the enhanced resistance towards antimicrobials has led to the development of an increasing number of strategies for biofilm eradication. Such strategies must take into account the existence of extracellular polymeric substances, which obstruct the diffusion of antibiofilm agents and assists in the maintenance of a well-defended microbial community. Within this context, nanoparticles have been studied for their drug delivery efficacy and easily customised surface. Nevertheless, there usually is a requirement for nanocarriers to be used in association with an antimicrobial agent; the intrinsically antimicrobial nanoparticles are most often made of metals or metal oxides, which is not ideal from ecological and biomedical perspectives. Based on this, the use of polymeric micelles as nanocarriers is appealing as they can be easily prepared using biodegradable organic materials. RESULTS: In the present work, micelles comprised of poly(lactic-co-glycolic acid) and dextran are prepared and then functionalised with curcumin. The effect of the functionalisation in the micelle's physical properties was elucidated, and the antibacterial and antibiofilm activities were assessed for the prepared polymeric nanoparticles against Pseudomonas spp. cells and biofilms. It was found that the nanoparticles have good penetration into the biofilms, which resulted in enhanced antibacterial activity of the conjugated micelles when compared to free curcumin. Furthermore, the curcumin-functionalised micelles were efficient at disrupting mature biofilms and demonstrated antibacterial activity towards biofilm-embedded cells. CONCLUSION: Curcumin-functionalised poly(lactic-co-glycolic acid)-dextran micelles are novel nanostructures with an intrinsic antibacterial activity tested against two Pseudomonas spp. strains that have the potential to be further exploited to deliver a secondary bioactive molecule within its core.

A bacterial endophyte exploits chemotropism of a fungal pathogen for plant colonization.

Soil-inhabiting fungal pathogens use chemical signals released by roots to direct hyphal growth towards the host plant. Whether other soil microorganisms exploit this capacity for their own benefit is currently unknown. Here we show that the endophytic rhizobacterium Rahnella aquatilis locates hyphae of the root-infecting fungal pathogen Fusarium oxysporum through pH-mediated chemotaxis and uses them as highways to efficiently access and colonize plant roots. Secretion of gluconic acid (GlcA) by R. aquatilis in the rhizosphere leads to acidification and counteracts F. oxysporum-induced alkalinisation, a known virulence mechanism, thereby preventing fungal infection. Genetic abrogation or biochemical inhibition of GlcA-mediated acidification abolished biocontrol activity of R. aquatilis and restored fungal infection. These findings reveal a new way by which bacterial endophytes hijack hyphae of a fungal pathogen in the soil to gain preferential access to plant roots, thereby protecting the host from infection.

Tailoring Nanoparticle-Biofilm Interactions to Increase the Efficacy of Antimicrobial Agents Against Staphylococcus aureus.

BACKGROUND: Considering the timeline required for the development of novel antimicrobial drugs, increased attention should be given to repurposing old drugs and improving antimicrobial efficacy, particularly for chronic infections associated with biofilms. Methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) are common causes of biofilm-associated infections but produce different biofilm matrices. MSSA biofilm cells are typically embedded in an extracellular polysaccharide matrix, whereas MRSA biofilms comprise predominantly of surface proteins and extracellular DNA (eDNA). Nanoparticles (NPs) have the potential to enhance the delivery of antimicrobial agents into biofilms. However, the mechanisms which influence the interactions between NPs and the biofilm matrix are not yet fully understood. METHODS: To investigate the influence of NPs surface chemistry on vancomycin (VAN) encapsulation and NP entrapment in MRSA and MSSA biofilms, mesoporous silica nanoparticles (MSNs) with different surface functionalization (bare-B, amine-D, carboxyl-C, aromatic-A) were synthesised using an adapted Stöber method. The antibacterial efficacy of VAN-loaded MSNs was assessed against MRSA and MSSA biofilms. RESULTS: The two negatively charged MSNs (MSN-B and MSN-C) showed a higher VAN loading in comparison to the positively charged MSNs (MSN-D and MSN-A). Cellular binding with MSN suspensions (0.25 mg mL-1) correlated with the reduced viability of both MSSA and MRSA biofilm cells. This allowed the administration of low MSNs concentrations while maintaining a high local concentration of the antibiotic surrounding the bacterial cells. CONCLUSION: Our data suggest that by tailoring the surface functionalization of MSNs, enhanced bacterial cell targeting can be achieved, leading to a novel treatment strategy for biofilm infections.

Interactions between functionalised silica nanoparticles and Pseudomonas fluorescens biofilm matrix: A focus on the protein corona.

Biofilms are microbial communities embedded in an extracellular polymeric matrix and display an enhanced tolerance to the action of antimicrobials. The emergence of novel functionalised nanoparticles is considered a promising avenue for the development of biofilm-specific antimicrobial technologies. However, there is a gap in the understanding of interactions between nanoparticles and the biofilm matrix. Particularly, questions are raised on how nanoparticle charge and surface groups play a role in aggregation when in contact with biofilm components. Herein we present the synthesis of four types of silica nanoparticles and undertake an analysis of their interactions with Pseudomonas fluorescens biofilm matrix. The effect of the biofilm matrix components on the charge and aggregation of the nanoparticles was assessed. Additionally, the study focused on the role of matrix proteins, with the in-depth characterisation of the protein corona of each nanoparticle by Liquid Chromatography with Tandem Mass Spectrometry experiments. The protein corona composition is dependent on the nanoparticle type; non-functionalised nanoparticles show less protein selectivity, whereas carboxylate-functionalised nanoparticles prefer proteins with a higher isoelectric point. These outcomes provide insights into the field of biofilm-nanoparticle interactions that can be valuable for the design of new nano-based targeting systems in future anti-biofilm applications.

Structure of Fungal α Mating Pheromone in Membrane Mimetics Suggests a Possible Role for Regulation at the Water-Membrane Interface.

Fusarium oxysporum is a highly destructive plant pathogen and an emerging pathogen of humans. Like other ascomycete fungi, F. oxysporum secretes α-pheromone, a small peptide that functions both as a chemoattractant and as a quorum-sensing signal. Three of the ten amino acid residues of α-pheromone are tryptophan, an amino acid whose sidechain has high affinity for lipid bilayers, suggesting a possible interaction with biological membranes. Here we tested the effect of different lipid environments on α-pheromone structure and function. Using spectroscopic and calorimetric approaches, we show that this peptide interacts with negatively charged model phospholipid vesicles. Fluorescence emission spectroscopy and nuclear magnetic resonance (NMR) measurements revealed a key role of the positively charged groups and Trp residues. Furthermore, NMR-based calculation of the 3D structure in the presence of micelles, formed by lipid surfactants, suggests that α-pheromone can establish an intramolecular disulfide bond between the two cysteine residues during interaction with membranes, but not in the absence of lipid mimetics. Remarkably, this oxidized version of α-pheromone lacks biological activity as a chemoattractant and quorum-sensing molecule. These results suggest the presence of a previously unidentified redox regulated control of α-pheromone activity at the surface of the plasma membrane that could influence the interaction with its cognate G-protein coupled receptor.

Heterologous Expression of PKPI and Pin1 Proteinase Inhibitors Enhances Plant Fitness and Broad-Spectrum Resistance to Biotic Threats.

Kunitz-type (PKPI) and Potato type I (Pin1) protease inhibitors (PIs) are two families of serine proteinase inhibitors often associated to plant storage organs and with well known insecticidal and nematicidal activities. Noteworthy, their ability to limit fungal and bacterial pathogenesis in vivo or to influence plant physiology has not been investigated in detail. To this aim, we generated a set of PVX-based viral constructs to transiently and heterologously express two potato PKPI (PKI1, PKI2) and three potato Pin1 (PPI3A2, PPI3B2, PPI2C4) genes in Nicotiana benthamiana plants, a widely used model for plant-pathogen interaction studies. Interestingly, transgenic plants expressing most of the tested PIs showed to be highly resistant against two economically important necrotrophic fungal pathogens, Botrytis cinerea and Alternaria alternata. Unexpectedly, overexpression of the PKI2 Kunitz-type or of the PPI2C4 and PPI3A2 Potato type I inhibitor genes also lead to a dramatic reduction in the propagation and symptom development produced by the bacterial pathogen Pseudomonas syringae. We further found that localized expression of PPI2C4 and PKI2 in N. benthamiana leaves caused an increase in cell expansion and proliferation which lead to tissue hypertrophy and trichome accumulation. In line with this, the systemic expression of these proteins resulted in plants with enhanced shoot and root biomass. Collectively, our results indicate that PKPI and Pin1 PIs might represent valuable tools to simultaneously increase plant fitness and broad-spectrum resistance toward phytopathogens.

A high throughput method to investigate nanoparticle entrapment efficiencies in biofilms.

The commercial use of nanoparticles has increased in recent years due to their unique characteristics, including high surface area, modifiable shape and surface charge and size-dependent properties. Consequently, a greater number of nanomaterials are now being released into the environment and inevitably interact with the natural ecosystem. Bacterial biofilms have the potential to capture and retain nanoparticles, however the factors determining the specific nanoparticle entrapment efficiencies of biofilms are not yet fully understood. Based on fluorescent intensity measurements we developed a simple and straightforward method that allowed the entrapment of different silica nanoparticles by two Pseudomonas strains to be quantified. It was determined that, regardless of nanoparticle size or surface functionalisation, Pseudomonas putida biofilms showed enhanced entrapment efficiencies compared to Pseudomonas fluorescens biofilms. It was also noted that both biofilms showed a higher entrapment capacity towards positively charged NPs. The method developed has the potential to be utilized for high throughput biofilm screening studies in order to develop a new understating of the relationship between nanoparticle characteristics and its uptake by bacterial biofilms.

Potential toxic elements in groundwater and their health risk assessment in drinking water of Limpopo National Park, Gaza Province, Southern Mozambique.

Concentrations of trace elements in drinking water affect its safety and acceptability for use. Potentially toxic element (PTE) contaminations are considered extremely hazardous because of toxicity, persistence, and bioaccumulative behaviour. Many areas in the Southern African Development Community are data poor and have poor accessibility. The results of our previous research identified the presence of fossil waters in southern Limpopo National Park. Groundwater and river water are the only sources of drinking water for the villages in the study area. The current study focuses on the understanding of trace element distribution and health perspectives of PTEs (Hg, U, Sr, B, and Mn) in the groundwater and surface water samples (rivers and lakes) collected within the buffer zone of the Limpopo National Park, Southern Mozambique. Two sampling campaigns (October 2016-March 2017) were carried out during the end of the wet season and the end of the dry season to analyse the differences. The results improved our knowledge of the occurrence of trace elements in drinking water in an area where water resources play a fundamental role-because of their scarcity-and where the climate is harsh. ICP-MS results provided information on concentration ranges, highlighting the exceedance of the permissible maximum limit of mercury imposed by the World Health Organization on several groundwater samples. In the buffer zone of Limpopo Park, the highest levels of risk seem to be associated with the presence of Hg and U in drinking water. The use of risk assessment markers such as non-cancer risk value (hazard quotient [HQ]) revealed the exceedance of HQ values for Hg and U. The HQ values are higher in the wet season than the dry season, and most of the exceedance has been found in groundwater. HQ values are higher in exposed children than exposed adults. The water of Lake Massingir seems to be safer than any other source, but people do not currently use it because of the distance between the lake and their villages. Proactive control and research on alternative solutions for the water needs of the population and on creation of water distribution are recommended. In the current study, drinking water was the only route of exposure that was evaluated. Therefore, it would be appropriate to investigate the concentrations of PTEs in crops, livestock, and any other potential pathways.

Surface functionalization-dependent localization and affinity of SiO2 nanoparticles within the biofilm EPS matrix.

The contribution of the biofilm extracellular polymeric substance (EPS) matrix to reduced antimicrobial susceptibility in biofilms is widely recognised. As such, the direct targeting of the EPS matrix is a promising biofilm control strategy that allows for the disruption of the matrix, thereby allowing a subsequent increase in susceptibility to antimicrobial agents. To this end, surface-functionalized nanoparticles (NPs) have received considerable attention. However, the fundamental understanding of the interactions occurring between engineered NPs and the biofilm EPS matrix has not yet been fully elucidated. An insight into the underlying mechanisms involved when a NP interacts with the EPS matrix will aid in the design of more efficient NPs for biofilm control. Here we demonstrate the use of highly specific fluorescent probes in confocal laser scanning microscopy (CLSM) to illustrate the distribution of EPS macromolecules within the biofilm. Thereafter, a three-dimensional (3D) colocalization analysis was used to assess the affinity of differently functionalized silica NPs (SiNPs) and EPS macromolecules from Pseudomonas fluorescens biofilms. Results show that both the charge and surface functional groups of SiNPs dramatically affected the extent to which SiNPs interacted and localized with EPS macromolecules, including proteins, polysaccharides and DNA. Hypotheses are also presented about the possible physicochemical interactions which may be dominant in EPS matrix-NP interactions. This research not only develops an innovative CLSM-based methodology for elucidating biofilm-nanoparticle interactions but also provides a platform on which to build more efficient NP systems for biofilm control.

Enhancing curcumin's solubility and antibiofilm activity via silica surface modification.

Bacterial biofilms are microbial communities in which bacterial cells in sessile state are mechanically and chemically protected against foreign agents, thus enhancing antibiotic resistance. The delivery of active compounds to the inside of biofilms is often hindered due to the existence of the biofilm extracellular polymeric substances (EPS) and to the poor solubility of drugs and antibiotics. A possible strategy to overcome the EPS barrier is the incorporation of antimicrobial agents into a nanocarrier, able to penetrate the matrix and deliver the active substance to the cells. Here, we report the synthesis of antimicrobial curcumin-conjugated silica nanoparticles (curc-NPs) as a possibility for dealing with these issues. Curcumin is a known antimicrobial agent and to overcome its low solubility in water it was grafted onto the surface of silica nanoparticles, the latter functioning as nanocarrier for curcumin into the biofilm. Curc-NPs were able to impede the formation of model P. putida biofilms up to 50% and disrupt mature biofilms up to 54% at 2.5 mg mL-1. Cell viability of sessile cells in both cases was also considerably affected, which is not observed for curcumin delivered as a free compound at the same concentration. Furthermore, proteomics of extracted EPS matrix of biofilms grown in the presence of free curcumin and curc-NPs revealed differences in the expression of key proteins related to cell detoxification and energy production. Therefore, curc-NPs are presented here as an alternative for curcumin delivery that can be exploited not only to other bacterial strains but also to further biological applications.

An RB-1 loss of function gene signature as a tool to predict response to neoadjuvant chemotherapy plus anti-HER2 agents: a substudy of the NeoALTTO trial (BIG 1-06).

BACKGROUND: Chemotherapy added to anti-HER2 agents (H) is the treatment of choice in patients with HER2+ early breast cancer. However, HER2+ tumours are clinically and biologically heterogeneous, and treatment response varies significantly by hormone receptor (HR) status and molecular subtype. Predictive biomarkers are needed in this context. This study assessed whether an RB-1 loss of function gene signature (RBsig) is predictive of response to neoadjuvant chemotherapy in combination with trastuzumab, lapatinib or both, within the NeoALTTO trial. METHODS: We collected RNA-sequencing data from pretreatment biopsies derived from the NeoALTTO trial. RBsig expression was computed retrospectively and correlated with pathological complete response (pCR) using receiver-operating characteristic (ROC) curves. The RBsig was dichotomised as High/Low in correspondence to the 25th percentile. Reported p values resulted from Fisher's exact test. RESULTS: Of 455 NeoALTTO patients, 244 were eligible for this substudy (HR+ n = 129; HR- n = 115). Overall, pCR rate was significantly higher in patients with RBsig High tumours than those with RBsig Low (35% versus 18% respectively; p = 0.01). The area under the ROC curve (AUC) was 0.60 (95% CI 0.52-0.67). A remarkably low pCR rate of 11% was seen in HR+/RBsig Low patients versus 28% in HR+/RBsig High. CONCLUSIONS: These results indicate RBsig may add valuable information to HER2 and HR expression, which may in turn inform treatment choices. HR+/HER2+/RBsig Low breast cancers exhibited the poorest pathological response following chemotherapy plus H. Accordingly, in such patients, endocrine therapy in combination with H and, possibly, a CDK4/6 inhibitor, may potentially prove to be a more effective treatment.

Ratiometric Imaging of the in Situ pH Distribution of Biofilms by Use of Fluorescent Mesoporous Silica Nanosensors.

Biofilms are communities of microorganisms enclosed in a self-generated matrix of extracellular polymeric substances. While biofilm recalcitrance and persistence are caused by several factors, a reduction in antimicrobial susceptibility has been closely associated with the generation of pH gradients within the biofilm structure. Cells embedded within the biofilm create a localized acidic microenvironment, which is unaffected by the external pH. Therefore, pH monitoring is a promising approach for understanding the complexities of a three-dimensional heterogeneous biofilm. A fluorescent pH nanosensor was designed through the synthesis of mesoporous silica nanoparticles (47 ± 5 nm diameter) conjugated to a pH-sensitive dye (fluorescein) and a pH-insensitive dye (rhodamine B) as an internal standard (dye-MSNs). The fluorescence intensity of fluorescein (IF) reduced significantly as the pH was decreased from 8.5 to 3.5. In contrast, the fluorescence intensity of rhodamine B (IR) remained constant at any pH. The ratio of IF/IR produced a sigmoidal curve with respect to the pH, in a working pH range between 4.5 and 7.5. Dye-MSNs enabled the measurement of pH gradients within Pseudomonas fluorescens WCS 365 biofilm microcolonies. The biofilms showed spatially distinct low-pH regions that were enclosed into large clusters corresponding to high-cell-density areas. Also present were small low-pH areas that spread indistinctly throughout the microcolony caused by the mass transfer effect. The lowest detected pH within the inner core of the microcolonies was 5.1, gradually increasing to a neutral pH toward the exterior of the microcolonies. The dye-MSNs were able to fully penetrate the biofilm matrix and allowed a quantitative ratiometric analysis of pH gradients and distribution throughout the biofilm, which was independent of the nanoparticle concentration.