Titania coated upconverting nanoparticles - Em. Wavelength:365 nm,particle size:40 nm

Cat. No.: T140929

GRADE & PURITY Em. Wavelength:365 nm,particle size:40 nm

Synonyms

TiO2 coated UCNs

Storage

Room temperature

Shipped In

Normal

Übersicht

This product contains NaYREF4@dSiO2@TiO2 (RE:Yb, Er, Tm, Gd, Mn, Lu) nanospheres, composed of upconverting nanoparticles coated by a dense silica layer followed by a titania layer, which can be well dispersed in aqueous media. The optimal excitation wavelength is 975 nm. The concentrations of Yb and Tm ions were optimized, giving out strong upconverted light at 365 nm
The upconversion emission at 365 nm generated by the UCNs upon 975 nm excitation can activate the photocatalytic capacity of TiO2 and thus produce reactive oxygen species which leads to cell death. This product can be used as NIR-light triggered photosensitizers for use in photodynamic therapy of deep tissues.

Specifications

Synonyme

TiO2 coated UCNs

Spezifikationen & Reinheit

Em. Wavelength:365 nm,particle size:40 nm

Storage

Room temperature

Verschickt in

Normal

Application Protocols

Item-specific tested applications/dilutions: Not specified for this item; refer to CoA/Spec Sheet.

General example protocols (literature/practice):

1. Preparing an aqueous dispersion (titania-shelled UCNPs)

• Add nanoparticle powder to ultrapure water (or 10 mM HEPES, pH 7.5) at 0.1–1 mg/mL. Sonicate in a bath for 2–5 min. Measure DLS and zeta potential; adjust pH or add 0.01–0.05 wt% PEG-phosphonate for stability. Filter through 0.45 µm if needed.

2. Measuring upconversion emission

• Place dispersion in a quartz cuvette. Excite at 808 or 980 nm using a fiber-coupled diode laser (verify beam power at the cuvette). Collect emission spectra (350–800 nm) with appropriate long-pass/short-pass filters. Record power dependence by varying irradiance and plotting log(Iem) vs log(Pexc).

3. NIR-driven photocatalysis (slurry test)

• In a quartz vial, combine substrate solution (e.g., 10–100 µM dye in water or alcohol) with UCNP@TiO2 (0.2–1 mg/mL). Stir and irradiate with NIR (808/980 nm). Monitor substrate decay by UV–vis at intervals. Include dark and no-catalyst controls.

4. Surface functionalization (phosphonate anchoring)

• Disperse particles in ethanol/water (9:1). Add phosphonic acid ligand (1–5 mM). Stir 2–12 h at room temperature. Wash by centrifugation/redispersion. Confirm attachment by FTIR (P–O–Ti bands) and TGA.

All procedures are illustrative and for research use only.

Biological Roles

Item-specific biological roles: Not applicable; this is an engineered inorganic nanomaterial with no intrinsic role in biology.

General research context (non-clinical, literature):

• Luminescent probes: Upconverting cores provide anti-Stokes emission under NIR excitation, enabling low-autofluorescence detection in biological research. Titania shells can improve colloidal stability in aqueous buffers and provide anchoring sites for biomolecular conjugation (e.g., silanes, phosphonates).
• Photobiology experiments: UCNP@TiO2 can be used to locally generate UV/VIS photons or reactive oxygen species under NIR, allowing controlled photochemical stimulation in vitro. Experimental design must manage dose and prevent nonspecific photooxidation.
• Biocompatibility considerations: TiO2 is widely studied; surface chemistry, size, and dose dominate cellular responses. Thorough characterization (hydrodynamic size, zeta potential, endotoxin testing) is essential before any biological assays. No medical or clinical claims are made.

Practical notes:

• Protein corona: In serum-containing media, rapid adsorption onto TiO2 can alter colloidal behavior; pre-coating with PEG-phosphonates or BSA may improve stability.
• Photothermal effects: 980 nm excitation can heat water; monitor temperature to decouple thermal from photochemical/photophysical effects.

All uses are for laboratory research only. Consult institutional biosafety committees when introducing nanomaterials into biological systems.

Buffer Applications

Item-specific buffer compatibility: Not specified for this item; refer to CoA/Spec Sheet.

General guidance for dispersing titania-coated UCNPs in aqueous buffers (literature/practice):

• pH control: Hydroxylated TiO2 surfaces exhibit isoelectric points around pH 5–6 (literature). For stable dispersions, operate sufficiently away from the IEP (e.g., pH ≥ 7.5) with low ionic strength to maintain electrostatic repulsion, or use polymeric steric stabilizers.
• Buffer selection:
  • Tris, HEPES: Mild interaction with TiO2; often better colloidal stability than phosphate at comparable ionic strengths.
  • Phosphate buffers: Strongly adsorb on TiO2; can induce flocculation or modify surface charge. If required, minimize concentration and screen pH/ionic strength.
  • Bicarbonate/carbonate: Can adsorb and shift surface charge; test empirically.
• Additives: Nonionic surfactants (e.g., Tween 20) at low levels or PEGylated phosphonates/catechols can enhance stability. BSA pre-coating may help but can quench emission in some cases.
• Preparation tips:
  • Exchange to buffer gradually (dialysis or stepwise dilution) to avoid osmotic shock and aggregation.
  • Sonicate gently (bath sonication) 1–5 minutes to redisperse. Filter through 0.45 µm if compatible.
  • Measure DLS and zeta potential before use; adjust pH/strength accordingly.

Note: UCNPs are insoluble; they form colloidal suspensions. Optimize buffer composition to balance colloidal stability with optical performance.

Green Alternatives

While titania-coated UCNPs are themselves inorganic and durable, greener choices focus on solvent systems, synthesis, and application design rather than replacing the functional material.

Greener considerations (literature/general):

• Aqueous processing: Favor water or low-toxicity alcohols for dispersion and device fabrication when surface chemistry permits, reducing VOC emissions compared to toluene/hexane.
• Ligand/shell choices: Use minimal, robust surface treatments (e.g., phosphonates, catechols, or silica interlayers) to improve aqueous stability and reduce need for surfactants.
• Illumination efficiency: Employ sensitizers enabling 808 nm excitation (lower water absorption) to decrease thermal load; optimize optical coupling to reduce input power and energy consumption.
• Recovery & reuse: As heterogeneous photocatalysts, UCNP@TiO2 can be magnetically retrievable if integrated with magnetic cores or supported on recyclable substrates, minimizing nanoparticle release.

Comparison snapshot (general, not product-specific):

• Nonpolar fabrication route (oleate-capped)
  • Pros: Excellent colloidal control, high crystallinity
  • Cons: Requires hydrocarbons/chlorinated solvents; post-synthesis ligand exchange needed for water use
• Aqueous/hydrothermal processing
  • Pros: Reduced VOCs, direct water compatibility
  • Cons: Potentially broader size distributions; lower crystallinity without high-temp anneals

Waste and EHS: Avoid acidifying rare-earth fluoride waste; collect and dispose according to institutional nanomaterial protocols to limit environmental release.

Pharmaceutical Uses

Not applicable for approved pharmaceutical products. This material is offered strictly for research use only.

General formulation research context (non-clinical, literature):

• Investigational delivery platforms: UCNP@TiO2 constructs are explored academically as luminescent tracers or light-harvesting components in experimental nanocarriers. The TiO2 shell provides robust inorganic interfaces for further coating (silica, polymers) to tailor dispersion behavior.
• Excipients/status: No compendial monograph exists for “titania-coated upconverting nanoparticles.” Any use in drug products would require extensive development and toxicological assessment. No therapeutic or diagnostic claims are made here.
• Analytical utility in manufacturing R&D: As durable optical tracers, UCNPs can serve as process surrogates in research-scale tracer studies under NIR illumination, without implying clinical application.

For any work toward regulated applications, researchers must develop full CMC packages including particle size distribution, surface chemistry, leachables/extractables, and stability—outside the scope of this product listing.

Physical Properties

Item-specific measured properties (this SKU):

• Particle size, size distribution, crystal phase, shell thickness, zeta potential, dispersant/ligands, concentration: Not specified for this item; refer to CoA/Spec Sheet.
• Bulk density, true density, refractive index (dispersion): Not specified for this item; refer to CoA/Spec Sheet.
• Solubility: UCNPs are insoluble solids; they form colloidal dispersions depending on surface ligands. Specific dispersibility for this item is not specified; refer to CoA/Spec Sheet.

General/literature values and notes (for context only; not product specifications):

• TiO2 density (anatase) ~3.9 g/cm³; rutile ~4.2 g/cm³ (literature). UCNP fluoride cores (e.g., NaYF4) ~4.2 g/cm³ (literature). Composite particle effective density lies between core and shell values.
• Optical behavior: Upon NIR excitation (commonly 808 or 980 nm depending on sensitizer), emission bands in VIS/UV. The TiO2 shell can absorb UV and participate in charge separation; UCNP-to-TiO2 energy/charge transfer is reported in literature for photocatalysis.
• Zeta potential: Strongly dependent on pH and surface chemistry; titania surfaces exhibit isoelectric points typically around pH 5–6 (anatase; literature). Functionalization can shift this markedly.
• Thermal stability: Inorganic core–shells are thermally robust; organic ligands (if present) desorb/decompose >200 °C in inert atmosphere (literature). Avoid sintering if colloidal redispersion is required.

Note: Nanoparticle melting/boiling points are not meaningful; focus on dispersion behavior, optical response, and surface chemistry.

Quality and Grades

• Item-specific grade/purity: Not specified for this item; refer to CoA/Spec Sheet.

How to evaluate quality for titania-coated upconverting nanoparticles (general guidance for researchers):

• Colloidal attributes: Hydrodynamic diameter, polydispersity index (PDI), and zeta potential indicate dispersion stability. Narrow size distributions (low PDI) are preferred for reproducible optical outputs.
• Structural verification: XRD for core phase (e.g., β-NaYF4 vs α-NaYF4 in common systems), evidence of TiO2 shell (TEM with lattice/fringe contrast, EDS line scans or STEM-EDS mapping). Raman can help differentiate anatase/rutile or amorphous titania.
• Optical quality: Upconversion emission spectra, absolute or relative upconversion quantum yield (UCQY), and power dependence (log–log slope). Shelling typically increases emission intensity by surface passivation.
• Surface chemistry: TGA for ligand loading; FTIR/XPS for functionality (–OH, Ti–O–Ti, carboxylates). For aqueous use, low residual organics and known isoelectric behavior across pH are beneficial.
• Purity considerations: Low residual ionic species (e.g., F−, Na+, nitrates), absence of free rare-earth salts, and minimal agglomerates. For catalytic uses, absence of extraneous transition metals is advantageous.

Documentation to request/consult: CoA/Spec Sheet, SDS, TEM micrographs, size distribution (DLS/NTA), zeta potential vs pH, UV–vis/NIR and emission spectra, and stability/shelf-life statements.

Reaction and Applications

Applications (research, non-clinical):

• Photocatalysis and photoredox: The TiO2 shell can accept upconverted VIS/UV photons from the UC core to generate electron–hole pairs, enabling oxidation/reduction of adsorbed substrates under NIR illumination. Reported uses include dye degradation, organic oxidations, and reductive dehalogenations (literature).
• Solar energy/upconversion-assisted processes: UCNP@TiO2 architectures are explored for NIR harvesting in dye-sensitized and perovskite solar cell research, photoelectrochemical water splitting, and CO2 reduction photocatalysis under NIR co-illumination (literature).
• Sensing and imaging (research only): Titania shells improve water compatibility and provide functional handles for bioconjugation (via silanes/phosphonates), enabling luminescent probes with reduced quenching. No clinical use implied.
• Surface chemistry: TiO2 offers robust anchoring via phosphonic acids, catechols, and silanes, facilitating further coating with silica, polymers, or biomolecules for tailored interfaces.

Practical tips (general):

• Light management: For 980 nm excitation (Yb-sensitized cores), water strongly absorbs; consider 808 nm systems or reduce pathlength to mitigate heating. Use beam shaping and power-density calibration; monitor temperature.
• Dispersion control: Brief probe or bath sonication improves deagglomeration; avoid prolonged high-power sonication that can fragment particles or strip ligands.
• Quenching and reabsorption: Shelling with TiO2 generally reduces surface quenching, but excessive shell thickness can attenuate emission; optimize shell growth for the intended application.
• Characterization coupling: Correlate catalytic rates or emission intensities with particle number concentration (via ICP-OES for metal content) rather than mass alone for reproducibility.

Reaction Conditions

Item-specific conditions are not specified; refer to CoA/Spec Sheet for any provided use notes. The following are general, literature-based parameters for UCNP@TiO2 in photocatalysis and photoredox research:

• Excitation sources: 808 nm diode lasers for Nd-sensitized cores; 980 nm lasers for Yb-sensitized cores. Typical irradiances 0.1–2 W/cm² at the sample surface; optimize to balance rate and heating. Use active cooling or stirring.
• Reactor setup: Quartz vials/cuvettes for optical access. For slurries, 0.1–5 mg/mL catalyst loading is common. Magnetic stirring ensures uniform exposure; maintain thin optical pathlengths in water at 980 nm.
• Atmosphere: Aerated conditions for oxidative pathways on TiO2; inert (N2/Ar) for reductive pathways or when oxygen quenches intermediates.
• Solvents: Water, alcohols (MeOH/EtOH/IPA), acetonitrile, or toluene depending on surface chemistry and reaction. Avoid strong acids/bases that can etch the shell or core; maintain pH 6–9 where possible for TiO2 stability.
• Additives: Sacrificial donors (e.g., triethanolamine, alcohols) for reductive quenching or electron scavengers (O2, persulfate) for oxidative routes (literature). Surface-bound photosensitizers or cocatalysts (e.g., Pt nanoparticles) can enhance specific reactions.
• Time/kinetics: Reactions often proceed over 0.5–8 h under continuous irradiation; monitor by GC/GC–MS/HPLC. Include dark controls and non-upconverting TiO2 controls to deconvolute mechanisms.

Note: Validate optical power at the sample using a calibrated photodiode; report temperature to separate thermal from photochemical contributions.

Safety and Handling

Item-specific hazard classification (GHS), pictograms, H/P statements: Not specified for this item; refer to the product SDS for authoritative safety information.

General safety guidance for titania-coated UCNP powders/dispersions (literature/best practice):

• Primary hazards: Nuisance dust and respiratory exposure to ultrafine particles. Handle powders in a certified fume hood or ventilated enclosure; avoid aerosol generation. For dispersions, avoid spray formation.
• PPE: Lab coat, safety glasses, and appropriate gloves (nitrile). Use a particulate respirator if airborne exposure is possible. Consider double-gloving when handling concentrated dispersions.
• Incompatibilities: Strong acids can attack rare-earth fluoride cores, potentially releasing fluoride; avoid acidifying waste. Strong bases can etch titania. Avoid strong oxidizers/reducers with organic ligands present.
• Photoreactivity: Under UV and, via upconversion, under NIR excitation, TiO2 surfaces can generate reactive oxygen species. Protect bulk suspensions from intense light when not in use to minimize unintended photocatalytic reactions with solvents or biomolecules.
• First aid (overview; defer to SDS): If inhaled, move to fresh air; seek medical attention if symptoms persist. Skin/eye contact: rinse with water for at least 15 minutes; remove contaminated clothing. If ingested, rinse mouth; do not induce vomiting; seek medical attention.
• Spill & disposal: Avoid dry sweeping; wet-wipe or use HEPA-filtered vacuum. Collect nanoparticle waste as hazardous; do not discharge to drains. Neutralize/contain without strong acids to prevent fluoride liberation.

Solvent Selection

Item-specific dispersibility/solvent recommendations: Not specified for this item; refer to CoA/Spec Sheet.

General guidance (nanoparticle dispersions depend on surface ligands and titania shell chemistry):

• Hydrophobic systems: If capped with long-chain carboxylates (e.g., oleate), dispersions are favored in nonpolar/apolar solvents (hexane, toluene, chloroform) and some ethers (TBME). Add small amounts of coordinating cosolvents (e.g., THF) cautiously to avoid ligand stripping.
• Hydrophilic/titania-dominant surfaces: Hydroxylated TiO2 shells tend to disperse in polar protic solvents (water, ethanol) with pH control and ionic-strength minimization. Phosphate buffers can adsorb strongly to TiO2; evaluate effects on stability and optical output.
• Surfactants/polymers: For aqueous media, electrosteric stabilizers such as PEG-phosphonates, poly(acrylic acid), or catechol-terminated PEG can improve stability on TiO2. For nonpolar media, additional oleic acid or amphiphiles can help control aggregation.
• Dielectric and polarity considerations: Upconversion is sensitive to local environment; high-refractive-index media can alter scattering and extraction efficiency. Avoid solvents that absorb strongly at the excitation wavelength (808/980 nm) to minimize heating.

Comparison (literature, typical):

• Water (pH 7–9): Good for hydroxylated TiO2 with polymer stabilizers; may need sonication.
• Ethanol/IPA: Useful for processing/coatings; moderate stability.
• Toluene/hexane: Preferred for oleate-capped particles; excellent dispersion if dry and oxygen-free.

Always filter dispersions (0.2–0.45 µm) before precise optical measurements to remove large agglomerates.

Storage and Reconstitution

• Storage conditions (item-specific): Room temperature (per Product Data). Protect from excessive light to avoid unintended photochemical processes. Keep container tightly closed. Shipped at ambient conditions.
• Shelf life: Not specified for this item; refer to CoA/Spec Sheet.

General guidance for nanomaterial handling:

• Form of supply: If provided as a dry powder, store desiccated to limit moisture uptake and agglomeration. If supplied as a dispersion, avoid freezing unless specified; freeze–thaw can induce irreversible aggregation.
• Reconstitution into dispersions:
  • Nonpolar media: For hydrophobic/oleate-capped materials, use dry, oxygen-free toluene or hexane. Add particles gradually with mild sonication. Optionally add 0.1–1 vol% oleic acid to aid stabilization.
  • Aqueous media: For hydroxylated TiO2 surfaces, start with DI water or low-ionic-strength buffers at pH 7–9. Employ brief bath sonication (2–5 min). Introduce polymeric stabilizers (e.g., PEG-phosphonate) if aggregation occurs.
• Handling tips: Minimize headspace agitation to reduce aerosolization. When scaling dispersions, work in enclosed systems and verify stability by DLS/zeta before critical experiments.

Always consult the product’s SDS and CoA for definitive storage and handling instructions. Research use only.

Structure and Identity

Titania coated upconverting nanoparticles (UCNPs) are inorganic core–shell nanomaterials in which an upconverting luminescent core is encapsulated by a conformal shell of titanium dioxide (TiO2, titania).

• Item-specific identifiers
  • CAS, CID, InChIKey, SMILES: Not specified for this item; refer to CoA/Spec Sheet.
  • Empirical formula and molecular weight: Not specified for this item; refer to CoA/Spec Sheet (nanoparticulate solid; composition depends on core dopants and shell thickness).
• Structural features (general, literature)
  • Core: Typically a rare-earth–doped host lattice (e.g., NaYF4:Yb,Er or Yb,Tm; other fluoride/oxide hosts possible). Sensitizer (e.g., Yb3+, Nd3+) absorbs NIR and transfers energy to activators (e.g., Er3+, Tm3+, Ho3+) to emit VIS/UV light.
  • Shell: An amorphous or crystalline TiO2 layer (anatase or amorphous at low-temperature coatings) that passivates the core surface, improves photostability, enables photocatalysis, and provides surface –OH for further functionalization.
  • Morphology: Commonly quasi-spherical cores with concentric shell; faceted particles possible depending on synthesis. Overall diameters in literature often tens of nanometers, governed by core size and TiO2 thickness.
  • Surface chemistry: As-synthesized UCNPs are often hydrophobic (oleate-capped); titania coating can render surfaces more hydrophilic and reactive toward silanes, phosphonates, and catechols. Actual ligand state for this item: Not specified; refer to CoA/Spec Sheet.
• 2D description in words: An inner luminescent nanoparticle (rare-earth–doped host) surrounded by a continuous, inorganic TiO2 shell presenting hydroxylated surface sites.

Synthetic Utility

As functional nanomaterials, titania-coated UCNPs can serve as heterogeneous photocatalysts or photonic additives in synthetic chemistry research.

• Heterogeneous photoredox catalyst scaffold (literature):
  • Mechanism: NIR excitation of the UC core generates VIS/UV photons that are harvested by the TiO2 shell to form electron–hole pairs. These drive redox events at the surface. Alternatively, direct UC emission can activate molecular photocatalysts tethered to TiO2.
  • Advantages: Enables use of NIR light (deep penetration, lower scattering) to perform UV/VIS photochemistry; simplifies catalyst recovery and reuse; reduces dye leaching compared to organic photocatalysts.
• Surface functionalization chemistry:
  • Robust anchoring of phosphonic acids, catechols, or silanes onto TiO2 allows immobilization of organocatalysts, transition-metal complexes, or organic substrates for proximity-enhanced photoreactions.
  • Subsequent coating (e.g., silica) can impart porosity and control mass transport.
• Example transformations (reported in literature):
  • Oxidations (alcohols to aldehydes/ketones), azo-dye degradation as test reactions, radical additions, and halide reductions under NIR irradiation via UCNP@TiO2.
• Practical considerations:
  • Match excitation wavelength to sensitizer (often 808 or 980 nm); ensure optical flux sufficient for the intended rate while controlling heating.
  • Verify that substrates and solvents do not strongly absorb at the excitation wavelength to avoid parasitic heating; degas or oxygenate depending on desired redox pathway.

Target Specificity

Not applicable. This product is a nanomaterial, not a biological targeting reagent or antibody. No antigen/epitope specificity, clone, isotype, or species reactivity is defined.