In vitro study of magnetic particle seeding for implant assisted-magnetic drug targeting

The concept of using magnetic particles (seeds) as the implant for implant assisted-magnetic drug targeting (IA-MDT) was analyzed in vitro. Since this MDT system is being explored for use in capillaries, a highly porous (ε∼70%), highly tortuous, cylindrical, polyethylene polymer was prepared to mimic capillary tissue, and the seeds (magnetite nanoparticles) were already fixed within. The well-dispersed seeds were used to enhance the capture of 0.87 μm diameter magnetic drug carrier particles (MDCPs) (polydivinylbenzene embedded with 24.8 wt% magnetite) under flow conditions typically found in capillary networks. The effects of the fluid velocity (0.015–0.15 cm/s), magnetic field strength (0.0–250 mT), porous polymer magnetite content (0–7 wt%) and MDCP concentration (C=5 and 50 mg/L) on the capture efficiency (CE) of the MDCPs were studied. In all cases, when the magnetic field was applied, compared to when it was not, large increases in CE resulted; the CE increased even further when the magnetite seeds were present. The CE increased with increases in the magnetic field strength, porous polymer magnetite content and MDCP concentration. It decreased only with increases in the fluid velocity. Large magnetic field strengths were not necessary to induce MDCP capture by the seeds. A few hundred mT was sufficient. Overall, this first in vitro study of the magnetic seeding concept for IA-MDT was very encouraging, because it proved that magnetic particle seeds could serve as an effective implant for MDT systems, especially under conditions found in capillaries.     

Synthesis of allylic thiocyanates and novel 1,3-thiazin-4-ones from 2-(bromomethyl)alkenoates and S-nucleophiles in aqueous medium

Allylic thiocyanates and novel heterocycles containing the 1,3-thiazin-4-one core are easily obtained in high yields and mild conditions by nucleophilic displacement of 2-(bromomethyl)alkenoates (derived from Morita-Baylis-Hillman adducts) with sulphur-centred nucleophiles in aqueous acetone at 25 °C. Treatment of allylic bromides with NaSCN gave the corresponding (Z)-2-(thiocyanomethyl)alkenoates, while the reaction with thiourea followed by a basic work-up selectively produced (5Z)-2-amino-5-arylidene-1,3-thiazin-4-ones. The structural assignments were confirmed by X-ray diffraction analysis.     

Combating small molecule environmental contaminants: detection and sequestration using functional nucleic acids

Small molecule contaminants pose a significant threat to the environment and human health. While regulations are in place for allowed limits in many countries, detection and remediation of contaminants in more resource-limited settings and everyday environmental sources remains a challenge. Functional nucleic acids, including aptamers and DNA enzymes, have emerged as powerful options for addressing this challenge due to their ability to non-covalently interact with small molecule targets. The goal of this perspective is to outline recent efforts toward the selection of aptamers for small molecules and describe their subsequent implementation for environmental applications. Finally, we provide an outlook that addresses barriers that hinder these technologies from being widely adopted in field friendly settings and propose a path forward toward addressing these challenges.

Small molecule contaminants pose a significant threat to the environment and human health.     

In vitro study of ferromagnetic stents for implant assisted-magnetic drug targeting

Implant-assisted-magnetic drug targeting (IA-MDT) was studied in vitro using a coiled ferromagnetic wire stent made from stainless steel 430 or 304, and magnetic drug carrier particle (MDCP) surrogates composed of poly(styrene/divinylbenzene) embedded with 20 wt% magnetite. The fluid velocity, particle concentration, magnetic field strength, and stent material all proved to be important for capturing the MDCP surrogates. Overall, this in vitro study further confirmed the important role of the ferromagnetic implant for attracting and retaining MDCPs at the target zone.     

In vitro study of magnetic particle seeding for implant-assisted-magnetic drug targeting: Seed and magnetic drug carrier particle capture

An implant-assisted-magnetic drug targeting system using seed particles as the implant to increase the capture of magnetic drug carrier particles (MDCPs) in capillary tissue was studied in vitro. Dextran-coated magnetite particles were used as seeds, polydivinylbenzene magnetite particles were used as MDCPs, and a polyethylene porous cylinder was used as surrogate capillary tissue. The results showed that seeds could be magnetically captured first and then used to magnetically capture the MDCPs, causing a significant increase in their collection compared to when the seeds were absent.     

Ferromagnetic seeding for the magnetic targeting of drugs and radiation in capillary beds

A new implant assisted-magnetic drug targeting approach is introduced and theoretically analyzed to demonstrate its feasibility. This approach uses ferromagnetic particles as seeds for collecting magnetic drug carrier particles at the desired site in the body, such as in a capillary bed near a tumor. Based on the capture cross section (λ_c) approach, a parametric study was carried out using a 2-D mathematical model to reveal the effects of the magnetic field strength (μ₀H₀=0.01–1.0 T), magnetic drug carrier particle radius (R_p=20–500 nm), magnetic drug carrier particle ferromagnetic material content (x_fm,p=20–80 wt%), average blood velocity (u_B=0.05–1.0 cm/s), seed radius (R_s=100–2000 nm), number of seeds (N_s=1–8), seed separation (h=0–8R_s), and magnetic drug carrier particle and seed ferromagnetic material saturation magnetizations (iron, SS 409, magnetite, and SS 304) on the performance of the system. Increasing the magnetic field strength, magnetic drug carrier particle size, seed size, magnetic drug carrier particle ferromagnetic material content, or magnetic drug carrier particle or seed saturation magnetization, all positively and significantly affected λ_c, while increasing the average blood velocity adversely affected it. Increasing the number of seeds or decreasing the seed separation, with both causing less significant increases in λ_c, verified that cooperative magnetic effects exist between the seeds that enhance the performance. Overall, these theoretical results were encouraging as they showed the viability of this minimally invasive, implant assisted-magnetic drug targeting approach for targeting drugs or radiation in capillary beds.     

Matrix Pearson Equations Satisfied by Koornwinder Weights in Two Variables

We consider Koornwinder’s method for constructing orthogonal polynomials in two variables from orthogonal polynomials in one variable. If semiclassical orthogonal polynomials in one variable are used, then Koornwinder’s construction generates semiclassical orthogonal polynomials in two variables. We consider two methods for deducing matrix Pearson equations for weight functions associated with these polynomials, and consequently, we deduce the second order linear partial differential operators for classical Koornwinder polynomials.     

In Vivo Anti-Inflammatory Effect,Antioxidant Activity,and Polyphenolic Content of Extracts from Capsicum chinense By-Products

By-products of Capsicum chinense Jacq., var Jaguar could be a source of bioactive compounds. Therefore, we evaluated the anti-inflammatory effect, antioxidant activity, and their relationship with the polyphenol content of extracts of habanero pepper by-products obtained from plants grown on black or red soils of Yucatán, Mexico. Moreover, the impact of the type of extraction on their activities was evaluated. The dry by-product extracts were obtained by maceration (ME), Soxhlet (SOX), and supercritical fluid extraction (SFE). Afterward, the in vivo anti-inflammatory effect (TPA-induced ear inflammation) and the in vitro antioxidant activity (ABTS) were evaluated. Finally, the polyphenolic content was quantified by Ultra-Performance Liquid Chromatography (UPLC), and its correlation with both bioactivities was analyzed. The results showed that the SFE extract of stems of plants grown on red soil yielded the highest anti-inflammatory effect (66.1 ± 3.1%), while the extracts obtained by ME and SOX had the highest antioxidant activity (2.80 ± 0.0052 mM Trolox equivalent) and polyphenol content (3280 ± 15.59 mg·100 g⁻¹ dry basis), respectively. A negative correlation between the anti-inflammatory effect, the antioxidant activity, and the polyphenolic content was found. Overall, the present study proposed C. chinense by-products as a valuable source of compounds with anti-inflammatory effect and antioxidant activity.