RESUMEN
The abnormal increase in low-density lipoprotein (LDL) in human blood is a main independent risk factor for the pathogenesis of atherosclerosis, whereas a reduced LDL level effectively lowers morbidity. It is important to develop LDL adsorption materials with high efficiency and selectivity, as well as to simplify their fabrication processes. In this paper, polysulfone (PSF), sulfonated polysulfone (SPSF), and sulfonated polysulfone/dextran (SPSF/GLU) membranes were successfully fabricated for LDL adsorption using a solution casting technique. Attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy measurements confirmed the success of the preparation. The water contact angle decreased from 89.7 ± 3.4° (PSF) to 76.4 ± 3.2° (SPSF) and to 71.2 ± 1.9° (SPSF/GLU), respectively. BSA adsorption testing showed that the SPSF/GLU with surface enrichment of sulfonate groups and glycosyl groups possessed higher resistance to protein solution. The adsorption and desorption behaviors of the studied samples in single-protein or binary-protein solutions were systematically investigated by enzyme-linked immunosorbent assay (ELISA), The results showed that SPSF/GLU, which had excellent resistance to protein adsorption, possessed a similar adsorption capacity to that of PSF. SPSF membrane exhibited excellent selective affinity for LDL in single and binary protein solutions, suggesting potential applications in LDL removal.
RESUMEN
The strong adhesion of thermally conductive silicone encapsulants on highly integrated electronic devices can avoid external damages and lead to an improved long-term reliability, which is critical for their commercial application. However, due to their low surface energy and chemical reactivity, the self-adhesive ability of silicone encapsulants to substrates need to be explored further. Here, we developed epoxy and alkoxy groups-bifunctionalized tetramethylcyclotetrasiloxane (D4H-MSEP) and boron-modified polydimethylsiloxane (PDMS-B), which were synthesized and utilized as synergistic adhesion promoters to provide two-component addition-cured liquid silicone rubber (LSR) with a good self-adhesion ability for applications in electronic packaging at moderate temperatures. The chemical structures of D4H-MSEP and PDMS-B were characterized by Fourier transform infrared spectroscopy. The mass percentage of PDMS-B to D4H-MSEP, the adhesion promoters content and the curing temperature on the adhesion strength of LSR towards substrates were systematically investigated. In detail, the LSR with 2.0 wt% D4H-MSEP and 0.6 wt% PDMS-B exhibited a lap-shear strength of 1.12 MPa towards Al plates when curing at 80 °C, and the cohesive failure was also observed. The LSR presented a thermal conductivity of 1.59 W m-1 K-1 and good fluidity, which provided a sufficient heat dissipation ability and fluidity for potting applications with 85.7 wt% loading of spherical α-Al2O3. Importantly, 85 °C and 85% relative humidity durability testing demonstrated LSR with a good encapsulation capacity in long-term processes. This strategy endows LSR with a good self-adhesive ability at moderate temperatures, making it a promising material requiring long-term reliability in the encapsulation of temperature-sensitive electronic devices.
RESUMEN
A polydimethylsiloxane armed with epoxy, alkoxy and acrylate groups was synthesized from silanol terminated-PDMS and epoxy and acrylate groups functionalized silane coupling agents, and utilized as the adhesion promoter (AP) to prepare addition-cured liquid silicone rubber that exhibited self-adhesion ability (SA-LSR) with biocompatible thermoplastic polyurethanes (TPU) sheets. The structural characteristics of AP were characterized by Fourier transform infrared (FTIR) spectroscopy, which demonstrated the strong adhesion to polyester-based TPU sheets due to a sufficient amount of acrylate groups, epoxy groups and silanol groups obtained by the hydrolysis of alkoxy groups. In detail, the peel-off strength of SA-LSR and TPU joints reached up to 7.63 N mm-1 after the optimization of adhesion promoter including type and content, and curing condition including time and temperature. The cohesive failure was achieved during the sample breakage process. Moreover, the SA-LSR showed a good storage stability under proper storage conditions. This design strategy provided the feasibility to combine the advantages of addition-cured liquid silicone rubber and plastics with low melting points, promoting the potential application range of those silicone-based materials.
RESUMEN
OBJECTIVE: To investigate the incidence of local reactions (LRs) and systemic reactions (SRs) of subcutaneous immunotherapy (SCIT) and to analyze the potential risk factors of such reactions in Chinese population. METHOD: This is a retrospective study on 234 dust mite sensitized patients with allergic rhinitis and asthma who received allergen immunotherapy in our hospital from 2003 to 2010. Chart review was conducted to capture clinical data of reactions to immunotherapy. Parameters included signs and symptoms, the onset of reaction, and interventions in treating such reactions, particularly, the administration of epinephrine (EPI) and adjustment of vaccine dosage due to LRs and SRs. RESULT: The 234 patients received a total of 7679 injections. Among them, 4973 LRs (64.8%) and 235 SRs (3.1%) were observed in 67 patients (28.6% of all patients). SRs included respiratory symptoms (205 events, 88.4%) and cutaneous symptoms (31.5%). Of the total of 235 SR events, 212 (90.2%) were presented as mild SRs and 23 (9.8%) were in severe SR category (grade III and grade IV, EAACI grading system). Overall, severe SRs accounted for 0.3% of total injections. Seventeen of the 23 SR events required epinephrine treatment (0.2% of total injections). Of the 67 patients, 61 completed the course of treatment after dose adjustment; 36 patients had their doses decreased prior to further advancing to target dose. Nineteen subjects tolerated splitting two injections at 30 minutes interval. Six patients advanced the dose based on protocol and another 6 had to stop immunotherapy. Most of the SRs (77.4%) occurred during the maintenance phase of immunotherapy. The levels of TIgE, SIgE D1 and SIgE D2 were found to be significantly higher in patients with SRs comparing to patients without SRs (P < 0.05). SRs more commonly occurred in patients with age less than 14 years than their older counterparts (95.5% vs. 85.6%, OR = 3.58, 95%CI = 1.040 - 12.322, P < 0.01). The incidence of SRs were significantly higher in asthma patients who received SCIT than non-asthma patients (OR = 2, 95%CI = 1.136 - 4.624). CONCLUSION: Our study suggests that risk factors of SRs include maintenance phase (higher allergen vaccine doses), patients with asthma, age of less than 14 years, higher levels of TIgE, and SIgE D1 and SIgE D2. Effective management includes proper dose adjustment, splitting doses into 2 injections at 30 min apart, and strictly following immunotherapy indications.