Fabrication of starch-based microparticles by an emulsification-crosslinking method

Protective Encapsulation of a Bioactive Compound in Starch-Polyethylene Glycol-Modified Microparticles: Degradation Analysis with Enzymes

Starch is a promising polymer for creating novel microparticulate systems with superior biocompatibility and controlled drug delivery capabilities. In this study, we synthesized polyethylene glycol (PEG)-modified starch microparticles and encapsulated folic acid using a solvent-mediated acid-base precipitation method with magnetic stirring, which is a simple and effective method. To evaluate particle degradation, we simulated physiological conditions by employing an enzymatic degradation approach. Our results with FTIR and SEM confirmed the successful synthesis of starch-PEG microparticles encapsulating folic acid. The average size of starch microparticles encapsulating folic acid was 4.97 μm and increased to 6.01 μm upon modification with PEG. The microparticles were first exposed to amylase at pH 6.7 and pepsin at pH 1.5 at different incubation times at physiological temperature with shaking. Post-degradation analysis revealed changes in particle size and morphology, indicating effective enzymatic degradation. FTIR spectroscopy was used to assess the chemical composition before and after degradation. The initial FTIR spectra displayed characteristic peaks of starch, PEG, and folic acid, which showed decreased intensities after enzymatic degradation, suggesting alterations in chemical composition. These findings demonstrate the ongoing development of starch-PEG microparticles for controlled drug delivery and other biomedical applications and provide the basis for further exploration of PEG-starch as a versatile biomaterial for encapsulating bioactive compounds.

Preparation of cassava starch-gelatin yolk-shell microspheres by water-in-water emulsion method

This paper reports the preparation and characterization of gelatin-cassava starch microspheres using the water-in-water emulsion technique. The effects of different weight ratios (10: 0, 9: 1, 8: 2, 7: 3, 6: 4, 5: 5) of starch to gelatin on the morphology, structure, thermal properties, and stability of microspheres were investigated. The morphology results showed that most microspheres had spherical shapes and smooth surfaces. When the weight ratio of starch to gelatin was 5: 5, the prepared microspheres formed a stable yolk-shell structure. The swelling capacity of the microspheres increased with the proportion of gelatin, up to 682.3 %. The gelatin and starch in the microspheres were compatible but not miscible. Compared with the native starch, the crystalline structure of microspheres changed from A-type to a mixture of B-type and V-type, and the relative crystallinity decreased. Differential scanning calorimetry results showed that the melting of microspheres involved both gelatin dissolution and starch gelatinization. Due to the formation of composite microspheres, the starch content decreased, and the release of reducing sugars from the microspheres upon hydrolysis was reduced. The gelatin-cassava starch microspheres are simple to prepare, biocompatible, and can be used as a potential material for microencapsulation.

Application of Starch, Cellulose, and Their Derivatives in the Development of Microparticle Drug-Delivery Systems

Micro- and nanotechnologies have been intensively studied in recent years as novel platforms for targeting and controlling the delivery of various pharmaceutical substances. Microparticulate drug delivery systems for oral, parenteral, or topical administration are multiple unit formulations, considered as powerful therapeutic tools for the treatment of various diseases, providing sustained drug release, enhanced drug stability, and precise dosing and directing the active substance to specific sites in the organism. The properties of these pharmaceutical formulations are highly dependent on the characteristics of the polymers used as drug carriers for their preparation. Starch and cellulose are among the most preferred biomaterials for biomedical applications due to their biocompatibility, biodegradability, and lack of toxicity. These polysaccharides and their derivatives, like dextrins (maltodextrin, cyclodextrins), ethylcellulose, methylcellulose, hydroxypropyl methylcellulose, carboxy methylcellulose, etc., have been widely used in pharmaceutical technology as excipients for the preparation of solid, semi-solid, and liquid dosage forms. Due to their accessibility and relatively easy particle-forming properties, starch and cellulose are promising materials for designing drug-loaded microparticles for various therapeutic applications. This study aims to summarize some of the basic characteristics of starch and cellulose derivatives related to their potential utilization as microparticulate drug carriers in the pharmaceutical field.

Fabrication of Microfiber-Templated Microfluidic Chips with Microfibrous Channels for High Throughput and Continuous Production of Nanoscale Droplets

A polydimethylsiloxane (PDMS) microfluidic chip with well-interconnected microfibrous channels was fabricated by using an electrospun poly(ε-caprolactone) (PCL) microfibrous matrix and 3D-printed pattern as templates. The microfiber-templated microfluidic chip (MTMC) was used to produce nanoscale emulsions and spheres through multiple emulsification at many small micro-orifice junctions among microfibrous channels. The emulsion formation mechanisms in the MTMC were the cross-junction dripping or Y-junction splitting at the micro-orifice junctions. We demonstrated the high throughput and continuous production of water-in-oil emulsions and polyethylene glycol-diacrylate (PEG-DA) spheres with controlled size ranges from 2.84 μm to 83.6 nm and 1.03 μm to 45.7 nm, respectively. The average size of the water droplets was tuned by changing the micro-orifice diameter of the MTMC and the flow rate of the continuous phase. The MTMC theoretically produced 58 trillion PEG-DA nanospheres per hour without high shear force. In addition, we demonstrated the higher encapsulation efficiency of the PEG-DA microspheres in the MTMC than that of the microspheres fabricated by ultrasonication. The MTMC can be used as a powerful platform for the large-scale and continuous productions of emulsions and spheres.

Impact on various properties of native starch after synthesis of starch nanoparticles: A review

In recent years, interdisciplinary research is more focused on particle size, which helps in exploring the relation between micro and macroscopic properties of various materials. Starch nanoparticles are generally synthesized by using acid/enzymatic hydrolysis, gamma irradiation, simple nanoprecipitation, ultra-sonication, and homogenization treatments. The properties like amylose content, pasting, rheological, morphological, size distribution, etc. are affected after the formation of nanoparticles from starch. This study emphasizes how various properties are changed in starch nanoparticles. Starch nanoparticles are mainly used in the formulation of nano-emulsion, nano starch-based composite film, and drug delivery. The impact on various native starch properties after the preparation of starch nanoparticles are less reported. So, all the aspects related to various starch properties and their nanoparticles are extensively reviewed in this study so that the listed findings can be utilized in future processes to increase the various foods and non-food utilization of starch nanoparticles.

Xylan microparticles for controlled release of mesalamine: Production and physicochemical characterization

Xylan extracted from corn cobs was used to produce mesalamine-loaded xylan microparticles (XMP5-ASA) by cross-linking polymerization using a non-hazardous cross-linking agent. The microparticles were characterized by thermal analysis (DSC/TG), X-ray diffraction (XRD), Infrared spectroscopy (FTIR-ATR) and scanning electron microscopy (SEM). A comparative study of the in vitro drug release from XMP5-ASA and from gastro-resistant capsules filled with XMP5-ASA (XMPCAP5-ASA) or 5-ASA was also performed. NMR, FTIR-ATR, XRD and DSC/TG studies indicated molecularly dispersed drug in the microparticles with increment on drug stability. The release studies showed that XMPCAP5-ASA allowed more efficient drug retention in the simulated gastric fluid and a prolonged drug release lasting up to 24 h. XMPCAP5-ASA retained approximately 48 % of its drug content after 6 h on the drug release assay. Thus, the encapsulation of 5-ASA into xylan microparticles together with gastro-resistant capsules allowed a better release control of the drug during different simulated gastrointestinal medium.

Water-in-Water Emulsion as a New Approach to Produce Mesalamine-Loaded Xylan-Based Microparticles

The water-in-water emulsion method has been reported as a technique able to prepare microparticles without using harmful solvents. However, there are few reports showing the encapsulation of small molecules into microparticles produced within this technique. The probable reason relays on the rapid diffusion of these molecules from the discontinuous phase to the continuous phase. In the present study, xylan microparticles containing mesalamine were produced and the doubled crosslinking approach, used to promote higher encapsulation rates, was disclosed. To achieve this goal, a 23 full factorial design was carried out. The results revealed that all formulations presented spherical-shaped microparticles. However, at specific conditions, only few formulations reached up to 50% of drug loading. In addition, the new xylan-based microparticles formulation retained almost 40% of its drug content after 12 h of a dissolution assay likely due to the degree of crosslinking. Thus, the doubled crosslinking approach used was effective on the encapsulation of mesalamine and may pave the way to successfully produce other polysaccharide-based carriers for clinical use.

Development of repaglinide microspheres using novel acetylated starches of bitter and Chinese yams as polymers

Tropical starches from Dioscorea dumetorum (bitter) and Dioscorea oppositifolia (Chinese) yams were acetylated with acetic anhydride in pyridine medium and utilized as polymers for the delivery of repaglinide in microsphere formulations in comparison to ethyl cellulose. Acetylated starches of bitter and Chinese yams with degrees of substitution of 2.56 and 2.70 respectively were obtained. Acetylation was confirmed by FTIR, ¹H NMR spectroscopy. A 3² factorial experimental design was performed using polymer type and drug-polymer ratio as independent variables. Particle size, swelling, entrapment and time for 50% drug release (t₅₀) were dependent variables. Contour plots showed the relationship between the independent factors and the response variables. All variables except swelling increased with drug: polymer ratio. Entrapment efficiency was generally in the rank of Bitter yam>Ethyl cellulose>Chinese yam. Repaglinide microspheres had size 50±4.00 to 350±18.10μm, entrapment efficiency 75.30±3.03 to 93.10±2.75% and t₅₀ 3.20±0.42 to 7.20±0.55h. Bitter yam starch gave longer dissolution times than Chinese yam starch at all drug-polymer ratios. Drug release fitted Korsmeyer-Peppas and Hopfenberg models. Acetylated bitter and Chinese yam starches were found suitable as polymers to prolong release of repaglinide in microsphere formulations.

Monodisperse aqueous microspheres encapsulating high concentration of l-ascorbic acid: insights of preparation and stability evaluation from straight-through microchannel emulsification

Stabilization of l-ascorbic acid (l-AA) is a challenging task for food and pharmaceutical industries. The study was conducted to prepare monodisperse aqueous microspheres containing enhanced concentrations of l-AA by using microchannel emulsification (MCE). The asymmetric straight-through microchannel (MC) array used here constitutes 11 × 104 μm microslots connected to a 10 μm circular microholes. 5–30% (w/w) l-AA was added to a Milli-Q water solution containing 2% (w/w) sodium alginate and 1% (w/w) magnesium sulfate, while the continuous phase constitutes 5% (w/w) tetraglycerol condensed ricinoleate in water-saturated decane. Monodisperse aqueous microspheres with average diameters (dav) of 18.7–20.7 μm and coefficients of variation (CVs) below 6% were successfully prepared via MCE regardless of the l-AA concentrations applied. The collected microspheres were physically stable in terms of their dav and CV for >10 days of storage at 40°C. The aqueous microspheres exhibited l-AA encapsulation efficiency exceeding 70% during the storage.

Supramolecular Complexation of Carbohydrates for the Bioavailability Enhancement of Poorly Soluble Drugs

In this review, a comprehensive overview of advances in the supramolecular complexes of carbohydrates and poorly soluble drugs is presented. Through the complexation process, poorly soluble drugs could be efficiently delivered to their desired destinations. Carbohydrates, the most abundant biomolecules, have diverse physicochemical properties owing to their inherent three-dimensional structures, hydrogen bonding, and molecular recognition abilities. In this regard, oligosaccharides and their derivatives have been utilized for the bioavailability enhancement of hydrophobic drugs via increasing the solubility or stability. By extension, polysaccharides and their derivatives can form self-assembled architectures with poorly soluble drugs and have shown increased bioavailability in terms of the sustained or controlled drug release. These supramolecular systems using carbohydrate will be developed consistently in the field of pharmaceutical and medical application.

Preparation of cationic starch microspheres and study on their absorption to anionic-type substance

Cationic starch microspheres (CSMs) were prepared from lab-made neutral starch-based microspheres using a cationic adsorbent, namely 3-chloro-2-hydroxypropyltrimethyl ammonium chloride, as the cationic etherifying agent. Detection by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and laser diffraction techniques revealed that CSMs had coarse surfaces with good sphericity and dispersibility. Differential thermal analysis showed the lower thermostability of the CSMs' main chains. Furthermore, scores of experiments confirmed that CSMs are capable of absorption to N-(phosphonomethyl) iminodiacetic acid (PMIDA), a type of anionic substance, which is the intermediate to the preparation of glyphosate, maximally up to 95.24 mg/g. Compared with the Freundlich isotherm model, the Langmuir isotherm model can better describe the absorption process. The kinetic study showed that the pseudo-second-order model demonstrated a better correlation of the experimental data in contrast with the pseudo-first-order model. It can be therefore concluded that the rate-limiting step was the chemical absorption rather than the mass transport.

Formation and Stability of Vitamin E Enriched Nanoemulsions Stabilized by Octenyl Succinic Anhydride Modified Starch

Vitamin E (VE) is highly susceptible to autoxidation; therefore, it requires systems to encapsulate and protect it from autoxidation. In this study, we developed VE delivery systems, which were stabilized by Capsul® (MS), a starch modified with octenyl succinic anhydride. Influences of interfacial tension, VE viscosity, molecular weight distribution, and surfactant type (MS versus Tween 80) on stability and droplet size obtained by high-pressure homogenization were investigated. Both surfactants reduced interfacial tension and small droplet diameters (<350 nm) were produced at high VE content (80% oil phase, w/w) and low emulsifier (2.5%, w/w), which was attributed to their molecular distribution and interfacial characteristics and the magnitude of disruptive forces generated within homogenizer. MS nanoemulsions were stable to droplet coalescence at high temperature–short time exposure (30, 55, 80°C; 30 min). Results indicated that MS can be used successfully to stabilize VE nanoemulsions at ambient temperatures. Such nanoemulsions may be incorporated in many food products.

Preparation of Polysaccharide-Based Microspheres by a Water-in-Oil Emulsion Solvent Diffusion Method for Drug Carriers

Polysaccharide-based microspheres of chitosan, starch, and alginate were prepared by the water-in-oil emulsion solvent diffusion method for use as drug carriers. Blue dextran was used as a water-soluble biomacromolecular drug model. Scanning electron microscopy showed sizes of the resultant microspheres that were approximately 100 μm or less. They were spherical in shape with a rough surface and good dispersibility. Microsphere matrices were shown as a sponge. Drug loading efficiencies of all the microspheres were higher than 80%, which suggested that this method has potential to prepare polysaccharide-based microspheres containing a biomacromolecular drug model for drug delivery applications.

Chitosan scaffolds with BMP-6 loaded alginate microspheres for periodontal tissue engineering

The aim of this study is to develop an effective growth factor releasing scaffold-microsphere system for promoting periodontal tissue engineering. Bone morphogenetic protein-6 (BMP-6)-loaded alginate microspheres in narrow size distribution were produced by optimising electrospraying conditions. The addition of these microspheres to chitosan gels produced a novel scaffold in which not only the pore sizes and interconnectivity were preserved, but also a controlled release vehicle was generated. Loading capacity was adjusted as 50 ng or 100 ng BMP-6 for each scaffold and the controlled release behaviour of BMP-6 from chitosan scaffolds was observed during seven days. Cell culture studies were carried out with rat mesenchymal stem cells derived from bone marrow in three groups; chitosan scaffolds, chitosan scaffolds containing BMP-6-loaded alginate microspheres and chitosan scaffolds with free BMP-6 in culture medium. Results showed that controlled delivery of BMP-6 from alginate microspheres has a significant effect on osteogenic differentiation.