Fabrication of uniform enzyme-immobilized carbohydrate microparticles with high enzymatic activity and stability via spray drying and spray freeze drying

Modern trends in the formulation of microparticles for lung delivery using porogens: methods, principles and examples

Inhalation drug administration is increasingly used for local pharmacotherapy of lung disorders and as an alternative route for systemic drug delivery. Modern inhalation powder systems aim to target drug deposition in the required site of action. Large porous particles (LPP), characterized by an aerodynamic diameter over 5 μm, density below 0.4 g/cm3, and the ability to avoid protective lung mechanisms, come to the forefront of the research. They are mostly prepared by spray techniques such as spray drying or lyophilization using pore-forming substances (porogens). These substances could be gaseous, solid, or liquid, and their selection depends on their polarity, solubility, and mutual compatibility with the carrier material and the drug. According to the pores-forming mechanism, porogens can be divided into groups, such as osmogens, extractable porogens, and porogens developing gases during decomposition. This review characterizes modern trends in the formulation of solid microparticles for lung delivery; describes the mechanisms of action of the most often used porogens, discusses their applicability in various formulation methods, emphasizes spray techniques; and documents discussed topics by examples from experimental studies.

An Overview of Crosslinked Enzyme Aggregates: Concept of Development and Trends of Applications

Enzymes are commonly used as biocatalysts for various biological and chemical processes in industrial applications. However, their limited operational stability, catalytic efficiency, poor reusability, and high-cost hamper further industrial usage. Thus, crosslinked enzyme aggregates (CLEAs) are developed as a better enzyme immobilization tool to extend the enzymes' operational stability. This immobilization method is appealing because it is simpler due to the absence of ballast and permits the collective use of crude enzyme cocktails. CLEAs, so far, have been successfully developed using a variety of enzymes, viz., hydrolases, proteases, amidases, lipases, esterases, and oxidoreductase. Recent years have seen the emergence of novel strategies for preparing better CLEAs, which include the combi- and multi-CLEAs, magnetics CLEAs, and porous CLEAs for various industrial applications, viz., laundry detergents, organic synthesis, food industries, pharmaceutical applications, oils, and biodiesel production. To better understand the different strategies for CLEAs' development, this review explores these strategies and highlights the relevant concerns in designing innovative CLEAs. This article also details the challenges faced during CLEAs preparation and solutions for overcoming them. Finally, the trending strategies to improve the preparation of CLEAs alongside their industrial application trends are also discussed.

Micro-fluidic Spray Freeze Dried Ciprofloxacin Hydrochloride-Embedded Dry Powder for Inhalation

Active pharmaceutical ingredient (API)-embedded dry powder for inhalation (AeDPI) is highly desirable for pulmonary delivery of high-dose drug. Herein, a series of spray freeze-dried (SFD) ciprofloxacin hydrochloride (CH)-embedded dry powders were fabricated via a self-designed micro-fluidic spray freeze tower (MFSFT) capable of tuning freezing temperature of cooling air as the refrigerant medium. The effects of total solid content (TSC), mass ratio of CH to _L-leucine (Leu) as the aerosol dispersion enhancer, and the freezing temperature on particle morphology, size, density, moisture content, crystal properties, flowability, and aerodynamic performance were investigated. It was found that the Leu content and freezing temperature had considerable influence on the fine particle fraction (FPF) of the SFD microparticles. The optimal formulation (CH/Leu = 7:3, TSC = 2%w/w) prepared at - 40°C exhibited remarkable effective drug deposition (~ 33.38%), good aerodynamic performance (~ 47.69% FPF), and excellent storage stability with ultralow hygroscopicity (~ 1.93%). This work demonstrated the promising feasibility of using the MFSFT instead of conventional liquid nitrogen assisted method in the research and development of high-dose AeDPI.

Microencapsulation of a Commercial Food-Grade Protease by Spray Drying in Cross-Linked Chitosan Particles

In this study, the use of spray-drying technology for encapsulating Flavourzyme® (protease–peptidase complex) was evaluated to overcome the limitations (low encapsulation efficiency and no large-scale production) of other encapsulation processes. To the best of our knowledge, spray drying has not been applied previously for the immobilization of this enzyme. Firstly, bovine serum albumin (BSA), as a model protein, was encapsulated by spray drying in chitosan and tripolyphoshate (TPP) cross-linked-chitosan shell matrices. The results showed that the chitosan–TPP microcapsules provided a high encapsulation efficiency and better protein stability compared to the non-crosslinked chitosan microcapsules. The effect of enzyme concentration and drying temperature were tested during the spray drying of Flavourzyme®. In this regard, an activity yield of 88.0% and encapsulation efficiency of 78.6% were obtained with a concentration of 0.1% (v/v) and an inlet temperature of 130 °C. Flavourzyme®-loaded chitosan microcapsules were also characterized in terms of their size and morphology using scanning electron microscopy and laser diffractometry.

Microencapsulation of nattokinase from fermentation by spray drying: Optimization, comprehensive score, and stability

Nattokinase from fermentation has recently gained more attention due to its beneficial effects on cardiovascular system. However, the instability of free nattokinase limits its application. The aim of the study was to develop a spray-drying microencapsulation process to obtain the nattokinase powder with high activity, high quality, and strong storage stability. Hence, the microencapsulation process of nattokinase from fermentation by spray drying was optimized. Experiments of single-factor and response surface methodology were used to assess the comprehensive scores and nattokinase activities. According to single-factor and response surface methodology results, optimum parameters of microencapsulation process of the nattokinase power by spray drying were 30% of mass ratio of wall materials, 139°C of air inlet temperature, 8 L/h of feed rate, and 80°C of outlet temperature. The final optimized result encompassed a comprehensive score of 96, nattokinase activity of 1,340 IU/ml, and moisture content of 4.1 ± 0.1%. In addition, the microencapsulated nattokinase power showed strong storage stability in the conditions of different temperatures and pH. After 30 days of storage, the nattokinase powder was still white or light yellow, with a special smell, no peculiar smell and paste taste, and no impurity. These results build the basis of further industrialization of the nattokinase powder from fermentation broth by spray drying.

Effects of particle formation behavior on the properties of fish oil microcapsules fabricated using a micro-fluidic jet spray dryer

Fish oil was encapsulated with whey protein isolate (WPI) as wall material using a Micro-Fluidic Jet Spray Dryer. The effects of core/wall material ratio, drying temperature and total solids content on the properties of microcapsules were studied. Low core/wall material ratios at 1:5 and 1:3 resulted in high encapsulation efficiency (EE) and excellent oxidative stability of microparticles during storage. Reducing the inlet temperature from 160 to 110 °C remarkably decreased EE from around 99 to 64.8%, associated with substantial increases in peroxide value during storage. The total solids content mainly altered the morphology of microcapsules, showing little influence on EE and oxidative stability. We proposed that the different drying conditions impacted on particle formation behavior during spray drying, which could be a crucial factor responsible for the differences in the quality attributes of microparticles. A low core/wall material ratio and high drying temperature facilitated the formation of a rigid protein skin at droplet surface during drying, whereas a high solids fraction in the droplets could limit possible droplet shrinkage. These factors contributed positively to the encapsulation of the lipophilic core material.

A review on microfluidics in the detection of food pesticide residues

This paper briefly explains the food safety problems related to pesticide residues and introduces microfluidics technology as a pesticide residue detection method. Three mainstream microfluidic detection devices are detailed: one driven by liquid surface tension, one by motor siphon drive, and one by centrifugal force. The advantages and disadvantages of each are considered in an analysis of future trends in microfluidic technology for pesticide detection.