Understanding Colorectal Cancer Patient Experiences with Family Practitioners in Canada.

Despite ongoing screening efforts, colorectal cancer (CRC) remains a leading cause of death in Canada. The aim of this study was to better understand the experiences of Canadian CRC patients with their family practitioners (FPs) during and after their CRC diagnosis. Patient-reported data were collected through an online questionnaire to understand their CRC diagnosis experiences and identify potential gaps in care. Various factors contributing to challenges throughout a patient's CRC diagnosis (e.g., delayed CRC diagnosis) were determined using descriptive, qualitative, and inferential analyses. These factors could be targeted to optimize CRC care. This study found that 40.6% of the 175 respondents were unaware of at least one of the following aspects of CRC prior to their diagnosis: early-age onset (EAO), symptoms, and screening procedures. While 84.6% had access to a family physician (FP) before their diagnosis, only 17.7% were diagnosed by FPs. Higher proportions of younger individuals experienced misdiagnoses and felt dismissed compared to older individuals. Only half felt fully informed about their diagnosis when it was explained to them by their FP, while 53.1% had their diagnosis explained in plain language. Transitioning towards patient-centred care would promote pre-diagnosis CRC awareness, address differences in management of CRC care (e.g., dismissal and support), and accommodate for age and health-literacy-related disparities, thereby improving CRC care pathways for patients. Future research should investigate FPs experiences in detecting CRC cases to develop educational resources and recommendations, enhancing early detection and improving patient outcomes (1).

A Survey Detailing Early Onset Colorectal Cancer Patient and Caregiver Experiences in Canada.

The incidence of early onset colorectal cancer (EOCRC) in Canada has increased. To address the growing incidence of EOCRC, Colorectal Cancer Canada (CCC) developed the Never Too Young (N2Y) program to identify gaps in care and evaluate patient and caregiver experiences with CRC. The survey was available online using SurveyMonkey across Canada between 12 December 2022 and 1 May 2023. The patient and caregiver survey consisted of 113 and 94 questions, respectively. A total of 108 EOCRC patients and 20 caregivers completed the survey. Many respondents were unaware of EOCRC (41.6%) and the disease symptoms (45.2%) before diagnosis. Patient age at diagnosis was between 45 and 50 years in 31.7%, and 72.8% of them were diagnosed at stage III or IV. A perception of an initial misdiagnosis was common (67.4%) for EOCRC patients, and 51.2% felt dismissed due to their age. Patients and caregivers reported impacts of EOCRC on their mental health, with 70.9% of patients expressing a need for support with depression and 93.3% of caregivers experiencing a constant fear of recurrence of their loved one's cancer. Improving the Canadian population's awareness of EOCRC (e.g., CRC symptoms) is important for ensuring timely diagnoses. Similarly, it is critical to ensure that healthcare providers are aware of the increase in EOCRC cases and the unique needs of these patients. Re-evaluation of the CRC screening age should be undertaken in Canada to determine whether lowering the start age to 45 years will improve outcomes in this demographic.

Impact of Systemic Delays for Patient Access to Oncology Drugs on Clinical, Economic, and Quality of Life Outcomes in Canada: A Call to Action.

Canada has one of the most complex and rigorous drug approval and public reimbursement processes and is, unfortunately, one of the countries with the longest delays in drug access. To assess the overall impact of systemic delays in access to cancer therapy, a targeted literature review (TLR) was performed to identify studies associated with the clinical, economic, and quality of life impacts of delayed access to oncology drugs. Using MEDLINE/PubMed databases and snowballing, four unique records met the eligibility criteria. Results revealed that clinical outcomes were the most impacted by systemic delays in access to oncology drugs (e.g., life years lost, overall survival, and progression-free survival). The four articles retrieved by the TLR specifically illustrated that a substantial number of life years could potentially be saved by increasing systemic efficiency regarding the development, approval, and reimbursement processes of new drugs for advanced malignancies. It is imperative that initiatives are put in place to improve the performance and speed of Canadian drug regulatory and health technology assessment (HTA) processes, especially for new cancer therapeutics. The proposed solutions in this paper include better coordination between HTA and Canadian payers to harmonize coverage decisions, international collaborations, information sharing, and national standards for timeliness in oncology drug access.

Canadian Landscape Assessment of Colorectal Cancer Screening during the COVID-19 Pandemic.

The COVID-19 pandemic caused disruptions in colorectal cancer (CRC) care by interrupting CRC screening across Canada, posing problems for program participants, patients, and physicians and no clear understanding of how provincial healthcare systems would adapt in the face of another pandemic or shock to the system. A nationwide online survey targeted to members of the National Colorectal Cancer Screening Network (NCCSN) using the SurveyMonkey platform was conducted to gain insight into the impact of the pandemic on CRC screening from March 2020 to March 2022 across all thirteen Canadian jurisdictions. The survey included 25 multiple-choice and free-text questions. Both quantitative and qualitative methods were used to analyze the data using Microsoft Excel and NVivo software. Twenty-one provincial and territorial representatives participated in the survey conducted between 13 May 2022 and 27 October 2022. All jurisdictions (100%) reported decreased screenings, including fecal immunochemical testing (FIT) or Fecal Occult Blood testing (FOBT) procedures, and subsequent diagnostic colonoscopies. The average wait time for colonoscopies due to a positive FIT/FOBT was 76 days. To mitigate the backlog and initiate an effective intervention plan, representatives highlighted some key points, including the importance of prioritizing high-risk patients. Survey results concluded that the COVID-19 pandemic impacted CRC screening across Canada. This landscape assessment can help inform intervention measures and policy-related solutions to create greater resilience for CRC screening in provincial and territorial healthcare systems.

Report from the Ready for the Next Round Thought-Leadership Roundtables on Building Resilience in Cancer Care and Control in Canada-Colorectal Cancer Canada; 2021.

(1) Background: The COVID-19 pandemic illuminated vulnerabilities in the Canadian health care system and exposed gaps and challenges across the cancer care continuum. Canada is experiencing significant disruptions to cancer-related services, and the impact these disruptions (delays/deferrals/cancellations) have on the health care system and patients are yet to be determined. Given the potential adverse ramifications, how can Canada's health care systems build resilience for future threats? (2) Methods: To answer this question, CCC facilitated a series of four thought-leadership roundtables, each representing the views of four different stakeholder groups: patients, physicians, health care system leaders, and researchers. (3) Results: Six themes of strength were identified to serve as a springboard for building resilience including, (1) advancing virtual care and digital health technologies to prevent future interruptions in cancer care delivery. (2) developing real-time data metrics, data sharing, and evidence-based decision-making. (3) enhancing public-private-non-profit partnerships to advance research and strengthen connections across the system. (4) advancing patient-centricity in cancer research to drive and encourage precision medicine approaches to care. (5) investing in training and hiring a robust supply of health care human resources. (6) implementing a national strategy and infrastructure to ensure inter-provincial collaborative data sharing (4). Conclusions: A resilient health care system that can respond to shocks and threats is not an emergency system; it is a robust everyday system that can respond to emergencies.

Patient and Patient Group Engagement in Cancer Clinical Trials: A Stakeholder Charter.

Background-to guide the implementation of patient centricity and engagement in cancer clinical trials (CTs) and to operationalize the Canadianized version of the Clinical Trials Transformation Initiative (C-CTTI) model, the development of a charter was identified by cancer CT stakeholders. Methods-the Canadian Cancer Trial Stakeholder Charter (the Charter) was initiated by Colorectal Cancer Canada (CCC) and developed via the-1-formation of an inclusive working group (WG) that drafted the document using recommendations collected during the development of the C-CTTI model; 2-socialization of the draft Charter to solicit feedback from cancer CT stakeholders, including those who attended the 2019 CCC Conference; and 3-incorporation of stakeholders' feedback and finalization of the Charter by the WG. Results-the Charter was built around five guiding principles-1-patient centricity; 2-commitment to education and training; 3-collaboration as equal and independent partners in research; 4-transparency and accountability; and 5-high standards in data collection integrity and honesty. These principles led to the Charter's five tenets, which stipulate stakeholder commitments, aiming to make CTs accessible to all patients, improve the design and implementation of CTs to benefit patients, expand recruitment and retention of patients in CTs, and further advance cancer research and treatment. Conclusions-the Charter is intended to integrate the patient voice into the Canadian cancer CT continuum. The next phases of the C-CTTI model include the adoption and implementation of the Charter, the establishment of a patient group training program, and the development of real-world evidence/real-world data methodologies.

Pd Catalyst Based on Hyperbranched Polypyridylphenylene Formed In Situ on Magnetic Silica Allows for Excellent Performance in Suzuki-Miyaura Reaction.

Here, for the first time, we developed a catalytic composite by forming a thin layer of a cross-linked hyperbranched pyridylphenylene polymer (PPP) on the surface of mesoporous magnetic silica (Fe3O4-SiO2, MS) followed by complexation with Pd species. The interaction of Pd acetate (PdAc) with pyridine units of the polymer results in the formation of Pd2+ complexes which are evenly distributed through the PPP layer. The MS-PPP-PdAc catalyst was tested in the Suzuki-Miyaura cross-coupling reaction with four different para-Br-substituted arenes, demonstrating enhanced catalytic properties for substrates containing electron withdrawing groups, and especially, for 4-bromobenzaldehyde. In this case, 100% selectivity and conversion were achieved with TOF of >23 000 h-1 at a very low Pd loading (0.032 mol %), a remarkable performance in this reaction. We believe these exceptional catalytic properties are due to the hyperbranched polymer architecture, which allows excellent stabilization of catalytic species as well as a favorable space for reacting molecules. Additionally, the magnetic character of the support allows for easy magnetic separation during the catalyst synthesis, purification, and reuse, resulting in energy and materials savings. These factors and excellent reusability of MS-PPP-PdAc in five consecutive uses make this catalyst promising for a variety of catalytic reactions.

Genetic Screen in Chlamydia muridarum Reveals Role for an Interferon-Induced Host Cell Death Program in Antimicrobial Inclusion Rupture.

Interferon-regulated immune defenses protect mammals from pathogenically diverse obligate intracellular bacterial pathogens of the genus Chlamydia Interferon gamma (IFN-γ) is especially important in controlling the virulence of Chlamydia species and thus impacts the modeling of human chlamydial infection and disease in mice. How IFN-γ contributes to cell-autonomous defenses against Chlamydia species and how these pathogens evade IFN-γ-mediated immunity in their natural hosts are not well understood. We conducted a genetic screen which identified 31 IFN-γ-sensitive (Igs) mutants of the mouse model pathogen Chlamydia muridarum Genetic suppressor analysis and lateral gene transfer were used to map the phenotype of one of these mutants, Igs4, to a missense mutation in a putative chlamydial inclusion membrane protein, TC0574. We observed the lytic destruction of Igs4-occupied inclusions and accompanying host cell death in response to IFN-γ priming or various proapoptotic stimuli. However, Igs4 was insensitive to IFN-γ-regulated cell-autonomous defenses previously implicated in anti-Chlamydia trachomatis host defense in mice. Igs4 inclusion integrity was restored by caspase inhibitors, indicating that the IFN-γ-mediated destruction of Igs4 inclusions is dependent upon the function of caspases or related prodeath cysteine proteases. We further demonstrated that the Igs4 mutant is immune restricted in an IFN-γ-dependent manner in a mouse infection model, thereby implicating IFN-γ-mediated inclusion destruction and host cell death as potent in vivo host defense mechanisms to which wild-type C. muridarum is resistant. Overall, our results suggest that C. muridarum evolved resistance mechanisms to counter IFN-γ-elicited programmed cell death and the associated destruction of intravacuolar pathogens.IMPORTANCE Multiple obligatory intracellular bacteria in the genus Chlamydia are important pathogens. In humans, strains of C. trachomatis cause trachoma, chlamydia, and lymphogranuloma venereum. These diseases are all associated with extended courses of infection and reinfection that likely reflect the ability of chlamydiae to evade various aspects of host immune responses. Interferon-stimulated genes, driven in part by the cytokine interferon gamma, restrict the host range of various Chlamydia species, but how these pathogens evade interferon-stimulated genes in their definitive host is poorly understood. Various Chlamydia species can inhibit death of their host cells and may have evolved this strategy to evade prodeath signals elicited by host immune responses. We present evidence that chlamydia-induced programmed cell death resistance evolved to counter interferon- and immune-mediated killing of Chlamydia-infected cells.

Inflammation-induced DNA methylation of DNA polymerase gamma alters the metabolic profile of colon tumors.

BACKGROUND: Inflammation, metabolism, and epigenetic modulation are highly interconnected processes that can be altered during tumorigenesis. However, because of the complexity of these interactions, direct cause and effect during tumorigenesis have been difficult to prove. Previously, using a murine model of inflammation-induced colon tumorigenesis, we determined that the promoter of the catalytic subunit of DNA polymerase gamma (Polg) is DNA hypermethylated and silenced in inflammation-induced tumors, but not in non-inflammation-induced (mock) tumors, suggesting that inflammation can induce silencing of Polg through promoting DNA methylation during tumorigenesis. Polg is the only mitochondrial DNA polymerase and mutations in Polg cause mitochondrial diseases in humans. Because of the role of mitochondria in metabolism, we hypothesized that silencing of Polg in inflammation-induced tumors would result in these tumors having altered metabolism in comparison to mock tumors. METHODS: Inflammation-induced and mock colon tumors and colon epithelium from a mouse model of inflammation-induced colon tumorigenesis were assayed for alterations in Polg expression, mitochondria, and metabolism. Organoids derived from these tissues were used to study the direct effect of loss of Polg on mitochondria and metabolism. RESULTS: We demonstrate that inflammation-induced tumors with reduced Polg expression have decreased mitochondrial DNA content and numbers of mitochondria compared to normal epithelium or mock tumors. Tumoroids derived from mock and inflammation-induced tumors retained key characteristics of the original tumors. Inflammation-induced tumoroids had increased glucose uptake and lactate secretion relative to mock tumoroids. shRNA-mediated knockdown of Polg in mock tumoroids reduced mtDNA content, increased glucose uptake and lactate secretion, and made the tumoroids more resistant to oxidative stress. CONCLUSIONS: These results suggest that inflammation-induced DNA methylation and silencing of Polg plays an important role in the tumorigenesis process by resulting in reduced mitochondria levels and altered metabolism. An enhanced understanding of how metabolism is altered in and drives inflammation-induced tumorigenesis will provide potential therapeutic targets.

Graphene Derivative in Magnetically Recoverable Catalyst Determines Catalytic Properties in Transfer Hydrogenation of Nitroarenes to Anilines with 2-Propanol.

Here, we report transfer hydrogenation of nitroarenes to aminoarenes using 2-propanol as a hydrogen source and Ag-containing magnetically recoverable catalysts based on partially reduced graphene oxide (pRGO) sheets. X-ray diffraction and X-ray photoelectron spectroscopy data demonstrated that, during the one-pot catalyst synthesis, formation of magnetite nanoparticles (NPs) is accompanied by the reduction of graphene oxide (GO) to pRGO. The formation of Ag0 NPs on top of magnetite nanoparticles does not change the pRGO structure. At the same time, the catalyst structure is further modified during the transfer hydrogenation, leading to a noticeable increase of sp2 carbons. These carbons are responsible for the adsorption of substrate and intermediates, facilitating a hydrogen transfer from Ag NPs and creating synergy between the components of the catalyst. The nitroarenes with electron withdrawing and electron donating substituents allow for excellent yields of aniline derivatives with high regio and chemoselectivity, indicating that the reaction is not disfavored by these functionalities. The versatility of the catalyst synthetic protocol was demonstrated by a synthesis of an Ru-containing graphene derivative based catalyst, also allowing for efficient transfer hydrogenation. Easy magnetic separation and stable catalyst performance in the transfer hydrogenation make this catalyst promising for future applications.

Zn2+ Ion Surface Enrichment in Doped Iron Oxide Nanoparticles Leads to Charge Carrier Density Enhancement.

Here, we report the development of monodisperse Zn-doped iron oxide nanoparticles (NPs) with different amounts of Zn (Zn x Fe3-x O4, 0 < x < 0.43) by thermal decomposition of a mixture of zinc and iron oleates. The as-synthesized NPs show a considerable fraction of wüstite (FeO) which is transformed to spinel upon 2 h oxidation of the NP reaction solutions. At any Zn doping amounts, we observed the enrichment of the NP surface with Zn2+ ions, which is enhanced at higher Zn loadings. Such a distribution of Zn2+ ions is attributed to the different thermal decomposition profiles of Zn and Fe oleates, with Fe oleate decomposing at much lower temperature than that of Zn oleate. The decomposition of Zn oleate is, in turn, catalyzed by a forming iron oxide phase. The magnetic properties were found to be strongly dependent on the Zn doping amounts, showing the saturation magnetization to decrease by 9 and 20% for x = 0.05 and 0.1, respectively. On the other hand, X-ray photoelectron spectroscopy near the Fermi level demonstrates that the Zn0.05Fe2.95O4 sample displays a more metallic character (a higher charge carrier density) than undoped iron oxide NPs, supporting its use as a spintronic material.

Overview on Patient Centricity in Cancer Care.

Successful implementation of treatment in cancer care partially depends on how patients' perspectives are taken into account, as preferences of health care professionals and patients may differ. Objectives of this exploratory research were (I) to identify patient preferences and values (PPVs) in cancer care as indicated by patient organizations (POs), (II) to determine how these PPVs are captured in cancer care guidelines and (III) to review how guidelines take into account these PPVs. Based on a survey developed and completed by 19 POs, a literature review was conducted to analyse how patient perspectives are incorporated in oncology treatment guidelines. Based on survey results traditional health technology assessment value propositions of oncology care, such as extended life, treatment-free remission and pain reduction, were also highly rated by POs. However, the heterogeneity of cancer PPVs were clearly reflected in the survey results. PPVs in cancer care guidelines were mostly limited to those micro-level aspects that are strictly related to health care provision, such as side-effects and comorbidities. Patient experience, emotional support and convenience of care were relatively neglected fields in the reviewed guidelines. Patient engagement was rarely presented in the guideline development phase. POs believe that patients should be encouraged to take an active role in their own care due to the heterogeneity of cancer patients and PPVs. Even if patient-centricity is a leading paradigm in cancer policy, based on our research it is not yet standard practice to include patients or POs at all appropriate levels of decision-making processes that are related to their health and well-being. Patient engagement should be an integral part of cancer care decision-making. This complexity must be reflected throughout policy making, avoiding a population level "one-size-fits-all" solution.

Enhancing the Catalytic Activity of Zn-Containing Magnetic Oxides in a Methanol Synthesis: Identifying the Key Factors.

A new family of Ni-, Co-, and Cr-doped Zn-containing magnetic oxide nanoparticles (NPs) stabilized by polyphenylquinoxaline (PPQ) and hyperbranched pyridylphenylene polymer (PPP) has been developed. These NPs have been synthesized by thermal decomposition of Zn and doping metal acetylacetonates in the reaction solution of preformed magnetite NPs, resulting in single-crystal NPs with spinel structure. For the PPQ-capped NPs, it was demonstrated that all three types of metal species (Fe, Zn, and a doping metal) reside within the same NPs, the surface of which is enriched with Zn and a doping metal, while the deeper layers are enriched with Fe. The Cr-doped NPs at the high Cr loading are an exception due to favored deposition of Cr on magnetite located in the NP depth. The PPP-capped NPs exhibit similar morphology and crystallinity; however, the detailed study of the NP composition was barred due to the high PPP amount retained on the NP surface. The catalyst testing in syngas conversion to methanol demonstrated outstanding catalytic properties of doped Zn-containing magnetic oxides, whose activities are dependent on the doping metal content and on the stabilizing polymer. The PPP stabilization allows for better access to the catalytic species due to the open and rigid polymer architecture and most likely optimized distribution of doping species. Repeat experiments carried out after magnetic separation of catalysts from the reaction mixture showed excellent catalyst stability even after five consecutive catalytic runs.

Ru-Containing Magnetically Recoverable Catalysts: A Sustainable Pathway from Cellulose to Ethylene and Propylene Glycols.

Biomass processing to value-added chemicals and biofuels received considerable attention due to the renewable nature of the precursors. Here, we report the development of Ru-containing magnetically recoverable catalysts for cellulose hydrogenolysis to low alcohols, ethylene glycol (EG) and propylene glycol (PG). The catalysts are synthesized by incorporation of magnetite nanoparticles (NPs) in mesoporous silica pores followed by formation of 2 nm Ru NPs. The latter are obtained by thermal decomposition of ruthenium acetylacetonate in the pores. The catalysts showed excellent activities and selectivities at 100% cellulose conversion, exceeding those for the commercial Ru/C. High selectivities as well as activities are attributed to the influence of Fe3O4 on the Ru(0)/Ru(4+) NPs. A facile synthetic protocol, easy magnetic separation, and stability of the catalyst performance after magnetic recovery make these catalysts promising for industrial applications.

Zinc-Containing Magnetic Oxides Stabilized by a Polymer: One Phase or Two?

Here we developed a new family of Zn-containing magnetic oxides of different structures by thermal decomposition of Zn(acac)2 in the reaction solution of preformed magnetite nanoparticles (NPs) stabilized by polyphenylquinoxaline. Upon an increase of the Zn(acac)2 loading from 0.15 to 0.40 mmol (vs 1 mmol of Fe(acac)3), the Zn content increases, and the Zn-containing magnetic oxide NPs preserve a spinel structure of magnetite and an initial, predominantly multicore NP morphology. X-ray photoelectron spectroscopy (XPS) of these samples revealed that the surface of iron oxide NPs is enriched with Zn, although Zn species were also found deep under the iron oxide NP surface. For all the samples, XPS also demonstrates the atom ratio of Fe(3+)/Fe(2+) = 2:1, perfectly matching Fe3O4, but not ZnFe2O4, where Fe(2+) ions are replaced with Zn(2+). The combination of XPS with other physicochemical methods allowed us to propose that ZnO forms an ultrathin amorphous layer on the surface of iron oxide NPs and also diffuses inside the magnetite crystals. At higher Zn(acac)2 loading, cubic ZnO nanocrystals coexist with magnetite NPs, indicating a homogeneous nucleation of the former. The catalytic testing in syngas conversion to methanol demonstrated outstanding catalytic properties of Zn-containing magnetic oxides, whose activities are dependent on the Zn loading. Repeat experiments carried out with the best catalyst after magnetic separation showed remarkable catalyst stability even after five consecutive catalytic runs.

Coat Protein-Dependent Behavior of Poly(ethylene glycol) Tails in Iron Oxide Core Virus-like Nanoparticles.

Here we explore the formation of virus-like nanoparticles (VNPs) utilizing 22-24 nm iron oxide nanoparticles (NPs) as cores and proteins derived from viral capsids of brome mosaic virus (BMV) or hepatitis B virus (HBV) as shells. To accomplish that, hydrophobic FeO/Fe3O4 NPs prepared by thermal decomposition of iron oleate were coated with poly(maleic acid-alt-octadecene) modified with poly(ethylene glycol) (PEG) tails of different lengths and grafting densities. MRI studies show high r2/r1 relaxivity ratios of these NPs that are practically independent of the polymer coating type. The versatility and flexibility of the viral capsid protein are on display as they readily form shells that exceed their native size. The location of the long PEG tails upon shell formation was investigated by electron microscopy and small-angle X-ray scattering. PEG tails were located differently in the BMV and HBV VNPs, with the BMV VNPs preferentially entrapping the tails in the interior and the HBV VNPs allowing the tails to extend through the capsid, which highlights the differences between intersubunit interactions in these two icosahedral viruses. The robustness of the assembly reaction and the protruding PEG tails, potentially useful in modulating the immune response, make the systems introduced here a promising platform for biomedical applications.

Fabrication of magnetically recoverable catalysts based on mixtures of Pd and iron oxide nanoparticles for hydrogenation of alkyne alcohols.

We report a novel method for development of magnetically recoverable catalysts prepared by thermal decomposition of palladium acetylacetonate in the presence of iron oxide nanoparticles (NPs). Depending on conditions, the reaction results either in a dispersed mixture of Pd and iron oxide NPs or in their aggregates. It was demonstrated that the Pd loading, reaction temperature, solvent, and iron oxide NP size and composition are crucial to control the reaction product including the degree of aggregation of Pd and iron oxide NPs, and the catalyst properties. The aggregation controlled by polarization and magnetic forces allows faster magnetic separation, yet the aggregate sizes do not exceed a few hundred nanometers, making them suitable for various catalytic applications. These NP mixtures were studied in a selective hydrogenation of 2-methyl-3-butyn-2-ol to 2-methyl-3-buten-2-ol, demonstrating clear differences in catalytic behavior depending on the catalyst structure. In addition, one of the catalysts was also tested in hydrogenation of 3-methyl-1-pentyn-3-ol and 3-methyl-1-nonyn-3-ol, indicating some specificity of the catalyst toward different alkyne alcohols.

Multicore iron oxide mesocrystals stabilized by a poly(phenylenepyridyl) dendron and dendrimer: role of the dendron/dendrimer self-assembly.

We report the formation of multicore iron oxide mesocrystals using the thermal decomposition of iron acetyl acetonate in the presence of the multifunctional and rigid poly(phenylenepyridyl) dendron and dendrimer. We thoroughly analyze the influence of capping molecules of two different architectures and demonstrate for the first time that dendron/dendrimer self-assembly leads to multicore morphologies. Single-crystalline ordering in multicore NPs leads to cooperative magnetic behavior: mesocrystals exhibit ambient blocking temperatures, allowing subtle control over magnetic properties using a minor temperature change.

Functionalization of monodisperse iron oxide NPs and their properties as magnetically recoverable catalysts.

Here we report the functionalization of monodisperse iron oxide nanoparticles (NPs) with commercially available functional acids containing multiple double bonds such as linolenic (LLA) and linoleic (LEA) acids or pyridine moieties such as 6-methylpyridine-2-carboxylic acid, isonicotinic acid, 3-hydroxypicolinic acid, and 6-(1-piperidinyl)pyridine-3-carboxlic acid (PPCA). Both double bonds and pyridine groups can be reacted with noble metal compounds to form catalytically active species in the exterior of magnetic NPs, thus making them promising magnetically recoverable catalysts. We determined that both LLA and LEA stabilize magnetic iron oxide NPs, allowing the formation of π-complexes with bis(acetonitrile)dichloropalladium(II) in the NP shells. In both cases, this leads to the formation of NP aggregates because of interparticle complexation. In the case of pyridine-containing ligands, only PPCA with two N-containing rings is able to provide NP stabilization and functionalization whereas other pyridine-containing acids did now allow sufficient steric stabilization. The interaction of PPCA-based particles with Pd acetate also leads to aggregation because of interparticle interactions, but the aggregates that are formed are much smaller. Nevertheless, the catalytic properties in the selective hydrogenation of dimethylethynylcarbinol (DMEC) to dimethylvinylcarbinol were the best for the catalyst based on LLA, demonstrating that the NP aggregates in all cases are penetrable for DMEC. Easy magnetic separation of this catalyst from the reaction solution makes it promising as a magnetically recoverable catalyst.

Polyphenylenepyridyl dendrimers as stabilizing and controlling agents for CdS nanoparticle formation.

Semiconductor nanoparticles (NPs) are being actively explored for applications in medical diagnostics and therapy and numerous electronic devices including solar cells. In this paper we demonstrate the influence of the third generation rigid polyphenylenepyridyl dendrimers (PPPDs) of a different architecture on the formation of well-defined CdS NPs. A high temperature approach to the synthesis of novel CdS/PPPD nanocomposites is feasible due to the high thermal stability of PPPDs. The PPPD architecture affects the CdS NP formation: larger NPs are obtained in the presence of dendrimers with 1,3,5-triphenylbenzene cores compared to those with tetrakis(4-ethynylphen-1-yl)methane cores. The reaction conditions such as concentrations of PPPDs and NP precursors and the temperature regime also influence the CdS NP sizes. For the first time, we elucidated a mechanism of CdS NP formation in a non-coordinating solvent through the CdO redispersion in the presence of PPPDs. Interesting optical properties of these CdS/PPPD nanocomposites make them promising candidates for imaging applications.