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Laser additive manufacturing of biodegradable magnesium alloy WE43: a detailed microstructure analysis
摘要： WE43, a magnesium alloy containing yttrium and neodymium as main alloying elements, has become a well-established bioresorbable implant material. Implants made of WE43 are often fabricated by powder extrusion and subsequent machining, but for more complex geometries laser powder bed fusion (LPBF) appears to be a promising alternative. However, the extremely high cooling rates and subsequent heat treatment after solidification of the melt pool involved in this process induce a drastic change in microstructure, which governs mechanical properties and degradation behaviour in a way that is still unclear. In this study we investigated the changes in the microstructure of WE43 induced by LPBF in comparison to that of cast WE43. We did this mainly by electron microscopy imaging, and chemical mapping based on energy-dispersive X-ray spectroscopy in conjunction with electron diffraction for the identification of the various phases. We identified different types of microstructure: an equiaxed grain zone in the center of the laser-induced melt pool, and a lamellar zone and a partially melted zone at its border. The lamellar zone presents dendritic lamellae lying on the Mg basal plane and separated by aligned Nd-rich nanometric intermetallic phases. They appear as globular particles made of Mg3Nd and as platelets made of Mg41Nd5 occurring on Mg prismatic planes. Yttrium is found in solid solution and in oxide particles stemming from the powder particles’ shell. Due to the heat influence on the lamellar zone during subsequent laser passes, a strong texture developed in the bulk material after substantial grain growth.
关键词： Rapid solidification,Microstructure,Bone scaffolds,Electron microscopy,Biodegradable implants,WE43,Laser powder bed fusion,Magnesium
更新于2025-11-21 11:20:48
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Biodegradable Micelles for NIR/GSH-Triggered Chemophototherapy of Cancer
摘要： The chemotherapy of stimuli-responsive drug delivery systems (SDDSs) is a promising method to enhance cancer treatment effects. However, the low efficiency of chemotherapy drugs and poor degradation partly limit the application of SDDSs. Herein, we report doxorubicin (DOX)-loading mixed micelles for biotin-targeting drug delivery and enhanced photothermal/photodynamic therapy (PTT/PDT). Glutathione (GSH)-responsive mixed micelles were prepared by a dialysis method, proportionally mixing polycaprolactone-disulfide bond-biodegradable photoluminescent polymer (PCL-SS-BPLP) and biotin-polyethylene glycol-cypate (biotin-PEG-cypate). Chemically linking cypate into the mixed micelles greatly improved cypate solubility and PTT/PDT effect. The micelles also exhibited good monodispersity and stability in cell medium (~119.7 nm), low critical micelles concentration, good biodegradation, and photodecomposition. The high concentration of GSH in cancer cells and near-infrared light (NIR)-mediated cypate decomposition were able to achieve DOX centralized release. Meanwhile, the DOX-based chemotherapy combined with cypate-based NIR-triggered hyperthermia and reactive oxygen species could synergistically induce HepG2 cell death and apoptosis. The in vivo experiments confirmed that the micelles generated hyperthermia and achieved a desirable therapeutic effect. Therefore, the designed biodegradable micelles are promising safe nanovehicles for antitumor drug delivery and chemo/PTT/PDT combination therapy.
关键词： photothermal therapy,photodynamic therapy,biodegradable,stimuli-responsive drug delivery systems,cypate
更新于2025-09-23 15:22:29
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Interventional Photothermal Therapy Enhanced Brachytherapy: A New Strategy to Fight Deep Pancreatic Cancer
摘要： Photothermal–radiotherapy (PT–RT) is an effective strategy for relieving hypoxia-related radiotherapy resistance and inducing tumor-specific cell apoptosis/necrosis. Nevertheless, limited tissue penetration of near-infrared (NIR) laser and the serious side effects of high-dose radiation severely hinder its applications for deep tumors. An interventional photothermal–brachytherapy (IPT–BT) technology is proposed here for the internal site-specific treatment of deep tumors. This technology utilizes a kind of biodegradable honeycomb-like gold nanoparticles (HGNs) acting as both internal photothermal agents and radiosensitizers. A high tumor inhibition rate of 96.6% is achieved in SW1990 orthotopic pancreatic tumor-bearing mice by HGNs-mediated IPT–BT synergistic therapy. Interestingly, this approach effectively causes double-stranded DNA damage and improves the oxygen supply and the penetration of nanoparticles inside the tumor. Therefore, it is believed that this strategy may open up a new avenue for PT–RT synergistic therapy of deep malignant tumors and has a significant impact on the future clinical translation.
关键词： photothermal therapy,pancreatic cancer,biodegradable,interventional,brachytherapy,honeycomb-like gold
更新于2025-09-23 15:22:29
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Ultrasmall MoS2 Nanodots Doped Biodegradable SiO2 Nanoparticles for Clearable FL/CT/MSOT Imaging Guided PTT/PDT Combination Tumor therapy
摘要： Recently, we developed ultrasmall molybdenum disulfide (MoS2) quantum dots for computed tomography (CT) and multispectral optoacoustic tomography (MSOT) image-guided photothermal therapy (PTT). But, due to the rapid body elimination and the limited blood circulation time, the tumor uptake of the dots is low. In our study, this problem was solved via designing an amino modified biodegradable nanomaterial based on MoS2 quantum dots doped disulfide-based SiO2 nanoparticles (denoted MoS2@ss-SiO2) for multimodal application. By integrating the MoS2 quantum dots into clearable SiO2 nanoparticles, this nanoplatform with an appropriate particle size can not only degrade and excrete in a reasonable period induced by the redox-responsive with the glutathione (GSH), but also exhibits a high tumor uptake due to the longer blood circulation time. Moreover, hyaluronic acid (HA) and chlorin e6 (Ce6) were adsorbed on the outer shell for the tumor targeting effect and photodynamic therapy, respectively. So this biodegradable and clearable theranostic nanocomposite applicable in integrated fluorescence(FL)/CT/MSOT imaging guided combined photothermal therapy (PTT) and photodynamic therapy (PDT) is very optimistic in biomedical applications in the future.
关键词： biodegradable,multi-modal imaging,clearable,combination tumor therapy,ultrasmall MoS2 quantum dots
更新于2025-09-23 15:22:29
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Novel Biodegradable Polymer Tethered Platinum (II) for Photoacoustic Imaging
摘要： Photoacoustic microscopy (PAM) is an emerging imaging diagnostic technique for various diseases. Coupled with contrast agents, photoacoustic (PA) imaging yields additional information to facilitate an accurate diagnosis. While many organic-based contrast agents, notably those of cyanine dyes, nanoparticles, polyhydroxy-fullerene and carbon nanotubes, have become available, the use of transition metal as contrast agent is scant. Here, for the first time, we report a platinum II-based biodegradable polymer for PA imaging that is capable of effective cellular internalization with very low cytotoxicity. The experiment results show great promise as a novel photoacoustic contrast agent as its detectable PA signal was observed both in cell imaging and in vivo rat cerebral vascular imaging via designed PAM. This work exemplifies the incorporation of transition metal complex with polymeric nanoparticles, further expanding the field of the ability of PA imaging.
关键词： Platinum,Biodegradable polymer,Photoacoustic imaging,Contrast agent,Transition metal
更新于2025-09-23 15:21:21
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Incidence of late-acquired stent malapposition of drug eluting stents with second generation permanent and biodegradable polymer coatings-A prospective, randomized comparison using optical coherence tomography
摘要： Objectives and Background: Polymer coatings of drug-eluting stents (DES) may induce allergic reactions and inflammation, resulting in late-acquired stent malapposition (LASM) with the risk of stent thrombosis. This study evaluated, if biodegradable polymer (BP) reduces the incidence of LASM compared to permanent polymer (PP) after treatment with newer generation DES. Methods and Results: Fifty patients with 59 lesions were randomized (2:1) to elective treatment with second generation PP-DES (n = 32, 39 stents), either Everolimus-eluting or Zotarolimus-eluting stents, or with BP-DES (Biolimus-eluting stents [BES]; n = 18, 20 stents) and underwent optical coherence tomography directly after implantation and after 1 year. After implantation acute stent malappositions (ASM) were documented in 30 stents (51%) distributed to 22 stents treated with PP-DES (56%) and 8 with BP-DES (40%; n.s.). After 1 year, late stent malappositions (LSM) were detected in 14 stents (24 %); ASM persisted (APSM) in 9 stents after one year (7 PP-DES—18%, 2 BES—10%), whereas ASM resolved in 21 stents. In addition, LASM was documented in nine stents including five stents without and four stents with additional APSM. All LASM were located in PP-DES (n = 9; 23%), none in BP-DES (P = 0.022). Compared to the reference lumen area, in-stent lumen area of stents without LASM was smaller due to neointimal hyperplasia (P = 0.021), whereas in-stent lumen area at maximum LASM of stents with LASM was larger due to positive remodeling (P = 0.002). Conclusions: In conclusion the use of BP-DES reduced the occurrence of LASM due to positive remodeling compared to second generation PP-DES.
关键词： malapposition,permanent polymer,drug eluting stents,optical coherence tomography,biodegradable polymer
更新于2025-09-23 15:21:01
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Shell-free Copper Indium Sulfide Quantum Dots Induce Toxicity <i>In Vitro</i> and <i>In Vivo</i>
摘要： Semiconductor quantum dots (QDs) are attractive fluorescent contrast agents for in vivo imaging due to their superior photophysical properties, but traditional QDs comprise toxic materials such as cadmium or lead. Copper indium sulfide (CuInS2, CIS) QDs have been posited as a non-toxic and potentially clinically translatable alternative; however, previous in vivo studies utilized particles with a passivating zinc sulfide (ZnS) shell, limiting direct evidence of the biocompatibility of the underlying CIS. For the first time, we assess the biodistribution and toxicity of unshelled CIS and partially zinc-alloyed CISZ QDs in a murine model. We show that bare CIS QDs breakdown quickly, inducing significant toxicity as seen in organ weight, blood chemistry, and histology. CISZ demonstrate significant, but lower, toxicity compared to bare CIS, while our measurements of core/shell CIS/ZnS are consistent with literature reports of general biocompatibility. In vitro cytotoxicity is dose-dependent on the amount of metal released due to particle degradation, linking degradation to toxicity. These results challenge the assumption that removing heavy metals necessarily reduces toxicity: indeed, we find comparable in vitro cytotoxicity between CIS and CdSe QDs, while CIS caused severe toxicity in vivo compared to CdSe. In addition to highlighting the complexity of nanotoxicity and the differences between the in vitro and in vivo outcomes, these unexpected results serve as a reminder of the importance of assessing the biocompatibility of core QDs absent the protective ZnS shell when making specific claims of compositional biocompatibility.
关键词： in vivo imaging,biodegradable,CIS,nanotoxicity,nanomedicine,CuInS2,fluorescent contrast agent,QDs
更新于2025-09-19 17:13:59
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[IEEE 2020 8th International Winter Conference on Brain-Computer Interface (BCI) - Gangwon, Korea (South) (2020.2.26-2020.2.28)] 2020 8th International Winter Conference on Brain-Computer Interface (BCI) - Implementation of multi-connected single-channel functional near-infrared spectroscopy system for hyperscanning study
摘要： A drug delivery system is used for targeting drugs to specific cells. Various drug carriers, that also reduce the side effects of unbound drugs, have been introduced and commercialized in the pharmaceutical field. Among them, synthetic biodegradable polymers have received much attention attributed to their low toxicity, controllable biodegradation rates, manufacturability, and low costs. This paper reviews the salient characteristics of biodegradable polymers as drug carriers and their microfabrication methods. The reviewed microfabrication methods include laser micromachining, rapid prototyping, replication, emulsification, microfluidic fabrication, and X-ray-lithography-based methods. For these microfabrication methods, critical dimensions, feature variety, solvent compatibility, production throughput, and tooling requirements are also summarized.
关键词： poly-capro-lactone (PCL),laser micromachining,emulsification,microfluidics,poly(lactic-co-glycolic acid) (PLGA),biodegradable polymers,Drug delivery systems (DDS),rapid prototyping,replication,x-ray-lithography,microfabrication,drug carriers
更新于2025-09-19 17:13:59
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Distarch Phosphate as a Matrix for the Generation of Quantum Dots
摘要： Generation of ZnS, CdS, CaS and MgS quantum dots (QDs) was attempted in the matrix of distarch phosphate, an anionic polysaccharide. Based on the analysis of FTIR spectra, thermograms and Differential Scanning Calorimetry, interactions of QDS with the matrix could be excluded. On generation of MgS QDs and also, to a certain extent, CaS QDs, hydrolysis of the salts generating these QDs took place. That process had an impact on the partial destruction of the matrix. Molecular weight and radii of gyration of the products showed that the generation of QDs was dependent on the properties of the matrix polysaccharide. The elasticity, plasticity and viscosity of the gels containing QDs were significantly lower than those of plain distarch phosphate. Generally these values changed with time similarly to gels free of QDs.
关键词： Biocomposites,Calcium sulfide,Cadmium sulfide,Magnesium sulfide,Zinc sulfide,Luminescent biodegradable foils
更新于2025-09-16 10:30:52
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On the Characterization of Novel Step-Index Biocompatible and Biodegradable poly(D,L- lactic acid) Based Optical Fiber
摘要： We report on the first step-index biodegradable polymer optical fiber (bioPOF) fabricated using commercially available polyesters, with a core made from poly(D,L-lactic-co-glycolic acid) and a cladding made from poly(D,L-lactic acid). We prepared the preforms with a rod-in-tube technique and the fibers with a standard heat drawing process. We discuss the chemical and optical properties of the polyesters along the fabrication process from polymer granulates to optical fiber. More specifically, we address the influence of the processing steps on the molecular weight and thermal properties of the polymers. Cutback measurements return an attenuation of 0.26 dB∕cm at 950 nm for fibers with an outer diameter of 1000 ± 50 μm, a core of 570 ±30 μm and a numerical aperture of 0.163. When immersed in phosphate-buffered saline (PBS), bioPOFs degrade over a period of 3 months, concurrent with a 91% molecular weight loss. The core decomposes already after 3 weeks and features a 85% molecular weight loss. There is no any additional optical loss caused by immersion in PBS during the first 30-40 min for a bioPOFs with a diameter of about 500 μm. Our result demonstrates that bioPOF can be suitable for applications requiring light delivery deep into living tissue, such as photodynamic therapy.
关键词： optical polymers,biodegradable materials,optical fibers,optical fiber materials,plastic optical fiber
更新于2025-09-12 10:27:22