Yongchun Liu

Temperature-Triggered Enzyme Immobilization and Release Based on Cross-Linked Gelatin Nanoparticles

A glucoamylase-immobilized system based on cross-linked gelatin nanoparticles (CLGNs) was prepared by coacervation method. This system exhibited characteristics of temperature-triggered phase transition, which could be used for enzyme immobilization and release. Their morphology and size distribution were examined by transmission electron microscopy and dynamic light scattering particle size analyzer. Their temperature-triggered glucoamylase immobilization and release features were also further investigated under different temperatures. Results showed that the CLGNs were regularly spherical with diameters of 155±5 nm. The loading efficiencies of glucoamylase immobilized by entrapment and adsorption methods were 59.9% and 24.7%, respectively. The immobilized enzyme was released when the system temperature was above 40°C and performed high activity similar to free enzyme due to the optimum temperature range for glucoamylase. On the other hand, there was no enzyme release that could be found when the system temperature was below 40°C. The efficiency of temperature-triggered release was as high as 99.3% for adsorption method, while the release of enzyme from the entrapment method was not detected. These results indicate that CLGNs are promising matrix for temperature-triggered glucoamylase immobilization and release by adsorption immobilization method.

High drug-loading nanomedicines: progress, current status, and prospects

Drug molecules transformed into nanoparticles or endowed with nanostructures with or without the aid of carrier materials are referred to as “nanomedicines” and can overcome some inherent drawbacks of free drugs, such as poor water solubility, high drug dosage, and short drug half-life in vivo. However, most of the existing nanomedicines possess the drawback of low drug-loading (generally less than 10%) associated with more carrier materials. For intravenous administration, the extensive use of carrier materials might cause systemic toxicity and impose an extra burden of degradation, metabolism, and excretion of the materials for patients. Therefore, on the premise of guaranteeing therapeutic effect and function, reducing or avoiding the use of carrier materials is a promising alternative approach to solve these problems. Recently, high drug-loading nanomedicines, which have a drug-loading content higher than 10%, are attracting increasing interest. According to the fabrication strategies of nanomedicines, high drug-loading nanomedicines are divided into four main classes: nanomedicines with inert porous material as carrier, nanomedicines with drug as part of carrier, carrier-free nanomedicines, and nanomedicines following niche and complex strategies. To date, most of the existing high drug-loading nanomedicines belong to the first class, and few research studies have focused on other classes. In this review, we investigate the research status of high drug-loading nanomedicines and discuss the features of their fabrication strategies and optimum proposal in detail. We also point out deficiencies and developing direction of high drug-loading nanomedicines. We envision that high drug-loading nanomedicines will occupy an important position in the field of drug-delivery systems, and hope that novel perspectives will be proposed for the development of high drug-loading nanomedicines.

Ratiometric Nanothermometer Based on Rhodamine Dye-Incorporated F127-Melamine-Formaldehyde Polymer Nanoparticle: Preparation, Characterization, Wide-Range Temperature Sensing, and Precise Intracellular Thermometry

A series of fluorescent nanothermometers (FTs) was prepared with Rhodamine dye-incorporated Pluronic F-127-melamine-formaldehyde composite polymer nanoparticles (R-F127-MF NPs). The highly soluble Rhodamine dye molecules were bound with Pluronic F127 micelles and subsequently incorporated in the cross-linked MF resin NPs during high-temperature cross-link treatment. The morphology and chemical structure of R-F127-MF NPs were characterized with dynamic light scattering, electron microscopy, and Fourier-transform infrared (FTIR) spectra. Fluorescence properties and thermoresponsivities were analyzed using fluorescence spectra. R-F127-MF NPs are found to be monodispersed, presenting a size range of 88-105 nm, and have bright fluorescence and high stability in severe treatments such as autoclave sterilization and lyophilization. By simultaneously incorporating Rhodamine B and Rhodamine 110 (as reference) dyes at a doping ratio of 1:400 in the NPs, ratiometric FTs with a high sensibility of 7.6%·°C(-1) and a wide temperature sensing range from -20 to 110 °C were obtained. The FTs exhibit good stability in solutions with varied pH, ionic strengths, and viscosities and have similar working curves in both intracellular and extracellular environments. Cellular temperature variations in Hela cells during microwave exposure were successfully monitored using the FTs, indicating their considerable potential applications in the biomedical field.

A self-monitored fluorescence DNA anti-counterfeiting system based on silica coated SYBR Green I/DNA gelatin nanoparticles

A novel strategy was developed to prepare silica-coated SYBR Green I (SG)/DNA gelatin nanoparticles (SSDG NPs) for fabricating a self-monitored anti-counterfeiting system. In this system, definite DNA was first entwined with positively charged gelatin to form DNA-loaded gelatin nanoparticles (DG NPs) in acid solution by electrostatic interaction. After changing the DG NPs surface charge to negative by adjusting the pH to neutral, positively charged SG was adsorbed by the electrostatic interaction and high affinity with DNA. Finally, DG NPs were coated with silica to protect the DNA. The SSDG NPs are stable and resistant to DNA degradation. The fluorescence is stable under extreme environments, such as acidic and basic solutions, high temperature and salt, oxidation, exogenous DNA, and photobleaching. The SSDG NPs-based anti-counterfeiting label is stable under the weather test, with a shelf-life of longer than one year. The activity of encapsulated DNA was self-monitored by fluorescence of SG, which can also realize rapidly nondestructive DNA detection for anti-counterfeiting. Further accurate detection was carried out by agarose gel electrophoresis of PCR amplification and even DNA sequencing. The system offers good potential for anti-counterfeiting and long-term DNA storage.

The effect of cationic starch on hemoglobin, and the primary attempt to encapsulate hemoglobin

Abstract Though starch has been a common material used for drug delivery, it has not been used as an encapsulation material for hemoglobin-based oxygen carriers. In this study, cationic amylose (CA) was synthesized by an etherification reaction. The interaction behaviors between CA and hemoglobin (Hb) were measured by zeta potential, size, and UV-Vis absorption spectra at different pH values. Cationic starch encapsulated Hb by electrostatic adhesion, reverse micelles, and cross-linking, and showed a core shell structure with a size of around 100 nm, when measured immediately after dispersing in PBS solution. However, we found that it was prone to swell, aggregate, and leak Hb with a longer duration of dispersal in PBS.

Progress of recyclable magnetic particles for biomedical applications

Recyclable magnetic particles constitute a class of particles that can be manipulated by external magnetic fields and reused multiple times. These particles consist of a magnetic part and a functional part and have been widely used in the biomedical field, such as in enzyme immobilization, biochemical separation, nucleic acid detection and antibacterial agents, owing to their advantages of convenient operation, high efficiency, mild separation, and easy recycling. In this review, we investigate the research status of recyclable magnetic particles, and discuss their preparation methods, types and recycling methods in detail. According to their structure, existing recyclable magnetic particles are divided into three main types: core-shell structure particles, matrix-dispersed structure particles and hollow structure particles. Each type of recyclable magnetic particle requires a treatment procedure for reuse, which includes direct reuse, washing treatment, chemical treatment and high-temperature calcination. To date, most recycling methods for magnetic particles belong to washing and chemical treatment, and few studies focus on novel magnetic recycling methods, owing to the lack of systemic summary and theoretical studies. We also point out the limitations of preparation and treatment methods, and predict the development direction of recyclable magnetic particles. We predict that recyclable magnetic particles will occupy an important position in the field of sustainable development and environmental protection, and considerable perspectives will be presented for the development of recyclable magnetic particles.