The effect of nanoparticle softness on the interfacial dynamics of a model polymer nanocomposite

The introduction of soft organic nanoparticles (NPs) into polymer melts has recently expanded the material design space for polymer nanocomposites, compared to traditional nanocomposites that utilize rigid NPs, such as silica, metallic NPs, and other inorganic NPs. Despite advances in the fabrication and characterization of this new class of materials, the effect of NP stiffness on the polymer structure and dynamics has not been systematically investigated. Here, we use molecular dynamics to investigate the segmental dynamics of the polymer interfacial region of isolated NPs of variable stiffness in a polymer matrix. When the NP-polymer interactions are stronger than the polymer-polymer interactions, we find that the slowing of segmental dynamics in the interfacial region is more pronounced for stiff NPs. In contrast, when the NP-polymer interaction strength is smaller than the matrix interaction, the NP stiffness has relatively little impact on the changes in the polymer interfacial dynamics. We also find that the segmental relaxation time τα of segments in the NP interfacial region changes from values lower than to higher than the bulk material when the NP-polymer interaction strength is increased beyond a "critical"strength, reminiscent of a binding-unbinding transition. Both the NP stiffness and the polymer-surface interaction strength can thus greatly influence the relative segmental relaxation and interfacial mobility in comparison to the bulk material

Status and prospects of percutaneous vertebroplasty combined with 125I seed implantation for the treatment of spinal metastases

Metastatic spinal tumours are the most common type of bone metastasis. Various methods have been used to treat metastatic spinal lesions, including radiotherapy, chemotherapy, isotope therapy, bisphosphonate therapy, analgesics, and surgery. Conservative treatments such as radiotherapy and chemotherapy are not appropriate and usually are ineffective in patients with vertebral fractures and/or spinal instability. Minimally invasive surgical treatments using non-vascular interventional technology, such as percutaneous vertebroplasty (PVP), have been successfully performed in the clinical setting. PVP is a non-invasive procedure that creates small wounds and is usually associated with only minor complications. In the present study, we will review the clinical status and prospects for the use PVP combined with (125)I seed implantation (PVPI) to treat spinal metastases. The scientific evidence for this treatment, including safety, efficacy, and outcome measures, as well as comparisons with other therapies, was analysed in detail. PVPI effectively alleviates pain in metastatic spinal tumour patients, and the use of interstitial (125)I seed implants can enhance the clinical outcomes. In conclusion, PVPI is a safe, reliable, effective, and minimally invasive treatment. The techniques of PVP and (125)I seed implantation complement each other and strengthen the treatment’s effect, presenting a new alternative treatment for spinal metastases with potentially wide application

Selection of Angiotensin I Converting Enzyme Inhibitory Peptides from Enzymatic Hydrolysate of Pinctada martensii Using Surface Plasmon Resonance

Surface plasmon resonance (SPR) technology was used to analyze the binding of the three ultrafiltration fractions of the protein hydrolysate of Pinctada martensii (PHPM) with angiotensin I converting enzyme (ACE) as a protein ligand. The amino acid sequences of the bound peptides were identified by mass spectrometry (MS) and those with strong inhibitory potential against ACE were selected and synthesized. The in vitro ACE inhibitory activity and inhibition type of the peptides were studied as well as their interaction with ACE. It was found that the ultrafiltration fraction with a molecular mass of 3 000–5 000 Da had a strong binding signal to ACE. Among the four synthesized ACE inhibitory peptides, SLPWPMKPMNLIE had the lowest 50% inhibitory concentration (IC50) value and bound to the hydrophobic pocket of the C domain in ACE through hydrogen bonding