A nanocomposite of rare earth upconversion nanoparticles and nanodiamonds for dual-mode imaging and drug delivery

Advancements and applications of upconversion nanoparticles in wound dressings

Wound healing is a complex process that requires effective management to prevent infections and promote efficient tissue regeneration. In recent years, upconversion nanoparticles (UCNPs) have emerged as promising materials for wound dressing applications due to their unique optical properties and potential therapeutic functionalities. These nanoparticles possess enhanced antibacterial properties when functionalized with antibacterial agents, helping to prevent infections, a common complication in wound healing. They can serve as carriers for controlled drug delivery, enabling targeted release of therapeutic agents to the wound site, allowing for tailored treatment and optimal healing conditions. These nanoparticles possess the ability to convert near-infrared (NIR) light into the visible and/or ultraviolet (UV) regions, making them suitable for therapeutic (photothermal therapy and photodynamic therapy) and diagnostic applications. In the context of wound healing, these nanoparticles can be combined with other materials such as hydrogels, fibers, metal-organic frameworks (MOFs), graphene oxide, etc., to enhance the healing process and prevent the growth of microbial infections. Notably, UCNPs can act as sensors for real-time monitoring of the wound healing progress, providing valuable feedback to healthcare professionals. Despite their potential, the use of UCNPs in wound dressing applications faces several challenges. Ensuring the stability and biocompatibility of UCNPs under physiological conditions is crucial for their effective integration into dressings. Comprehensive safety and efficacy evaluations are necessary to understand potential risks and optimize UCNP-based dressings. Scalability and cost-effectiveness of UCNP synthesis and manufacturing processes are important considerations for practical applications. In addition, efficient incorporation of UCNPs into dressings, achieving uniform distribution, poses an important challenge that needs to be addressed. Future research should prioritize addressing concerns regarding stability and biocompatibility, efficient integration into dressings, rigorous safety evaluation, scalability, and cost-effectiveness. The purpose of this review is to critically evaluate the advantages, challenges, and key properties of UCNPs in wound dressing applications to provide insights into their potential as innovative solutions for enhancing wound healing outcomes. We have provided a detailed description of various types of smart wound dressings, focusing on the synthesis and biomedical applications of UCNPs, specifically their utilization in different types of wound dressings.

Erbium-ytterbium containing upconversion mesoporous bioactive glass microspheres for tissue engineering: luminescence monitoring of biomineralization and drug release

The development of functional biomaterials with real-time monitoring of mineralization processes, drug release and biodistribution has potential applications but remains an unsolved challenge. Herein, erbium- and ytterbium- containing mesoporous bioactive glass microspheres (MBGs:Er/Yb) with blue and red emission at an excitation wavelength of 980 nm were synthesized by a sol-gel combined with organic template method. As the concentration of Yb3+ ions gradually increases, the emission intensity of the MBGs:Er/Yb exhibits a clear concentration quenching effect. Combined with in vitro bioactivity tests, the optimal molar ratio of Er3+/Yb3+ was determined to be 4:3. Therefore, MBGs:4Er/3Yb was selected for in vitro biomineralization and drug release monitoring. The results of biomineralization monitoring show that the upconversion luminescence intensity is closely related to the degree of biomineralization. The upconversion luminescence intensity of MBGs:4Er/3Yb is quenched with the increase of the degree of biomineralization. The degree of luminescence quenching during biomineralization can be semiquantized. Drug release monitoring experiments showed that the anticancer drug doxorubicin hydrochloride (DOX) was successfully loaded into MBGs:4Er/3Yb and selectively quenched the green emission. When DOX was released, the green emission recovered stably, and It/I0 increased gradually. Moreover, there was a linear relationship between It/I0 and cumulative drug release, indicating that DOX-MBGs:4Er/3Yb is highly sensitive to DOX release, and monitoring the It/I0 values of DOX-MBGs:4Er/3Yb can achieve real-time tracking of the DOX release process to a certain extent. In conclusion, MBGs:4Er/3Yb has potential application as an upconversion luminescence biomonitoring material in the field of bone tissue engineering. STATEMENT OF SIGNIFICANCE: Mesoporous bioactive glasses have great potential for applications in bone tissue repair due to their excellent biological properties, but the effective information of the repair process cannot be grasped in a timely manner. Therefore, real-time monitoring of mineralization and drug release processes will be beneficial to obtain the degree of healing and optimize the amount and distribution of drugs to improve targeted therapeutic effects. For biomaterials, in vitro biological properties determine their biological properties in vivo, where the environment is more complex and diverse, and thus in vitro biomonitoring is particularly crucial. The organic combination of physical properties and biological properties will also provide a feasible idea for the development of biomaterials.

NIR-to-NIR and NIR-to-Vis up-conversion of SrF2:Ho3+nanoparticles under 1156 nm excitation

Recently, the up-converting (UC) materials, containing lanthanide (Ln³⁺) ions have attracted considerable attention because of the multitude of their potential applications. The most frequently investigated are UC systems based on the absorption of near-infrared (NIR) radiation by Yb³⁺ions at around 975-980 nm and emission of co-dopants, usually Ho³⁺, Er³⁺or Tm³⁺ions. UC can be observed also upon excitation with irradiation with a wavelength different than 975-980 nm. The most often studied systems capable of UC without the use of Yb³⁺ion are those based on the properties of Er³⁺ions, which show luminescence resulting from the excitation at 808 or 1532 nm. However, also other Ln³⁺ions are worth attention. Herein, we focus on the investigation of the UC phenomenon in the materials doped with Ho³⁺ions, which reveal unique optical properties upon the NIR irradiation. The SrF₂NPs doped with Ho³⁺ions in concentrations from 4.9% to 22.5%, were synthesized by using the hydrothermal method. The structural and optical characteristics of the obtained SrF₂:Ho³⁺NPs are presented. The prepared samples had crystalline structure, were built of NPs of round shapes and their sizes ranged from 16.4 to 82.3 nm. The NPs formed stable colloids in water. Under 1156 nm excitation, SrF₂:Ho³⁺NPs showed intense UC emission, wherein the brightest luminescence was recorded for the SrF₂:10.0%Ho³⁺compound. The analysis of the measured lifetime profiles and dependencies of the integral luminescence intensities on the laser energy allowed proposing the mechanism, responsible for the observed UC emission. It is worth mentioning that the described SrF₂:Ho³⁺samples are one of the first materials for which the UC luminescence induced by 1156 nm excitation was obtained.

Upconversion, MRI imaging and optical trapping studies of silver nanoparticle decorated multifunctional NaGdF4:Yb,Er nanocomposite

The multifunctional upconversion nanoparticles (UCNPs) are fascinating tool for biological applications. In the present work, photon upconverting NaGdF₄:Yb,Er and Ag nanoparticles decorated NaGdF₄:Yb,Er (NaGdF₄:Yb,Er@Ag) nanoparticles were prepared using a simple polyol process. Rietveld refinement was performed for detailed crystal structural and phase fraction analysis. The morphology of the NaGdF₄:Yb,Er@Ag was examined using high-resolution transmission electron microscope, which reveals silver nanoparticles of 8 nm in size were decorated over spherical shaped NaGdF₄:Yb,Er nanoparticles with a mean particle size of 90 nm. The chemical compositions were confirmed by EDAX and inductively coupled plasma-optical emission spectrometry analyses. The upconversion luminescence (UCL) of NaGdF₄:Yb,Er at 980 nm excitation showed an intense red emission. After incorporating the silver nanoparticles, the UCL intensity decreased due to weak scattering and surface plasmon resonance effect. The VSM magnetic measurement indicates both the UCNPs possess paramagnetic behaviour. The NaGdF₄:Yb,Er@Ag showed computed tomography imaging. Magnetic resonance imaging study exhibited better T1 weighted relaxivity in the NaGdF₄:Yb,Er than the commercial Gd-DOTA. For the first time, the optical trapping was successfully demonstrated for the upconversion NaGdF₄:Yb,Er nanoparticle at near-infrared 980 nm light using an optical tweezer setup. The optically trapped UCNP possessing paramagnetic property exhibited a good optical trapping stiffness. The UCL of trapped single UCNP is recorded to explore the effect of the silver nanoparticles. The multifunctional properties for the NaGdF₄:Yb,Er@Ag nanoparticle are demonstrated.