Binary and Tertiary Complex Based on Short-Chain Glucan and Proanthocyanidins for Oral Insulin Delivery

β-Cyclodextrin/dialdehyde glucan-coated keratin nanoparticles for oral delivery of insulin

Successful oral insulin administration can considerably enhance the quality of life (QOL) of diabetes patients who must frequently take insulin injections. However, Oral insulin administration is seriously hampered by gastrointestinal enzymes, wide pH range, mucus and mucosal layers, which limit insulin oral bioavailability to ≤2 %. Herein, we developed a simple, inexpensive and safe dual β-cyclodextrin/dialdehyde glucan-coated keratin nanoparticle (β-CD-K-IN-DG). The resulted β-CD-K-IN-DG not only gave the ultra-high insulin loading (encapsulation efficiency (98.52 %)), but also protected insulin from acid and enzymatic degradation. This β-CD-K-IN-DG had a notable hypoglycemic effect, there was almost 80 % insulin release after 4 h of incubation under hyperglycemic conditions. Ex vivo results confirmed that β-CD-K-IN-DG possessed high mucus-penetration ability. Transepithelial transport and uptake mechanism studies revealed that bypass transport pathway and endocytosis promoted β-CD-K-IN-DG entered intestinal epithelial cells, thus increased the bioavailability of insulin (12.27 %). The improved stability of insulin during in vivo transport implied that β-CD-K-IN-DG might be a potential tool for the effective oral insulin administration.

Preparation and Characterization of Chitosan Nanofiber: Kinetic Studies and Enhancement of Insulin Delivery System

Insulin-loaded nanofibers were prepared using chitosan as a natural polymer. The loaded insulin with polyethylene oxide was used for preparing monolayer batch S1. Nanofiber S1 was coated by seven layers of film on both sides to form batch S2 as a sandwich containing Layer A (CS, PEG and PEO) and Layer B (PEG and PEO) using electrospinning apparatus. SEM, TEM and FT-IR techniques were used to confirm the drug loading within the composite nanofibers. The in vitro activity that provided a sustained and controlled release of the drug from the nanofiber batch was studied at different pH values spectrophotometrically using a dialysis method. In batches S1 and S2, the release of insulin from nanofiber proceeds via burst release necessary to produce the desired therapeutic activity, followed by slow step. The rate and the percentage release of insulin in batch S2 are found to be higher at all pH values.

Low-Cytotoxicity, Broad-Spectrum Corn Starch-Based Antibacterial Particles that Inhibit Multidrug-Resistant Bacteria

Antimicrobial resistance is a serious problem in biomedical applications that seriously increases the risk of medical failure. Therefore, developing highly efficient antibacterial agents that inhibit the growth of multidrug-resistant bacteria is a long-standing research goal. In this report, a low-cytotoxicity and highly efficient alternative to antibiotics was designed and prepared using edible corn starch as the scaffold and 2-hydroxypropyl-trimethylammonium chloride chitosan (HTCC) as the antimicrobial agent. The HTCC/starch particles were found to have a positively charged surface over a wide pH range and to possess broad-spectrum and highly efficient antimicrobial properties. These particles inhibited the growth of standard Gram-positive and Gram-negative bacteria from the China Pharmacopoeia and a clinical multidrug-resistant bacterial strain. Moreover, after treating the HTCC/starch particles with simulated gastric fluid (SGF, pH 1.2) for 4 h, the growth of clinical multidrug-resistant Escherichia coli (NT 2036) was inhibited effectively, indicating that these particles tolerate a gastric acid environment. Although the mass of SGF-treated HTCC/starch particles required to achieve similar antibacterial activity was ∼20-fold that of chloramphenicol or ampicillin, antibiotic-containing products require considerable amounts of pharmaceutical excipients to prepare. Therefore, the HTCC/starch particles described herein are potentially cost-effective alternatives to antibiotics that resolve the antimicrobial resistance issue, especially for inhibiting the growth of pathogenic intestinal bacteria.

Materials and structure of polysaccharide-based delivery carriers for oral insulin: A review

Diabetes mellitus is a chronic metabolic disease that affects >500 million patients worldwide. Subcutaneous injection of insulin is the most effective treatment at present. However, regular needle injections will cause pain, inflammation, and other adverse consequences. In recent years, significant progress has been made in non-injectable insulin preparations. Oral administration is the best way of administration due to its simplicity, convenience, and good patient compliance. However, oral insulin delivery is hindered by many physiological barriers in the gastrointestinal tract, resulting in the low relative bioavailability of direct oral insulin delivery. To improve the relative bioavailability, a variety of insulin delivery vectors have been developed. Polysaccharides are used to achieve safe and effective insulin loading due to their excellent biocompatibility and protein affinity. The functional characteristics of polysaccharide-based delivery carriers, such as pH responsiveness, mucosal adhesion, and further functionalization modifications, enhance the gastrointestinal absorption and bioavailability of insulin. This paper reviews the materials and structures of oral insulin polysaccharide-based carriers, providing ideas for further improving the relative bioavailability of oral insulin.

Properties of Allicin-Zein Composite Nanoparticle Gelatin Film and Their Effects on the Quality of Cold, Fresh Beef during Storage

Allicin is a kind of natural antimicrobial active substance, but its water solubility is poor, and it is easy to degrade. In order to improve the stability and bioavailability of allicin, allicin-zein composite nanoparticles (Al-Ze) were prepared by the combination method of antisolvent precipitation and electrostatic deposition, and their characteristic parameters, such as average particle size, polydispersity index (PDI), and ζ-potential, were analyzed. Then, Al-Ze was used as the delivery carrier for the active substance (allicin), and gelatin with good film-forming properties was selected as the film-forming matrix to prepare Al-Ze gelatin films. The optical properties, mechanical properties, and characterization parameters were used to analyze the prepared composite materials; the results confirmed that Al-Ze gelatin film has good mechanical properties and barrier properties. The prepared film was applied to the storage of cold, fresh beef, and the quality change of beef was monitored at 4 °C. The results showed that Al-Ze gelatin film could effectively delay the quality deterioration of beef. This paper provides a new idea and data support for the application of Al-Ze gelatin film in meat storage and fresh-keeping, and offers new insight for the promotion and application of allicin in the food industry.

Ethanol-mediated synthesis of γ-cyclodextrin-based metal-organic framework as edible microcarrier: performance and mechanism

Here, an ethanol-mediated method was introduced to fabricate γ-cyclodextrin-based metal-organic frameworks (γ-CD-MOFs) as microcarriers for epigallocatechin-3-gallate (EGCG). Through adjusting ethanol gas diffusion temperature and ethanol liquid feed speed, we achieved control of crystallization efficiency and crystals size without extra surfactants. Under the sequential regulatory by ethanol in two phases, the obtained γ-CD-MOFs with cubic shape exhibited excellent crystallinity, high surface area, and uniform size distribution. Through the interplay of hydrogen bonding, hydrophobic interactions and π stacking, EGCG molecules could be stored efficiently within cavities and tunnels of the γ-CD-MOFs with high load capability of 334 mg g^-1. More importantly, the incorporation of EGCG within frameworks wouldn't disintegrate the unique body-centered cubic structure of γ-CD-MOFs, in turn, would improve the thermostability and antioxidative activity of EGCG. Significantly, all food-grade materials ensured the γ-CD-MOFs high acceptance and applicability for food and biomedical applications.

Progress and prospects of polysaccharide-based nanocarriers for oral delivery of proteins/peptides

The oral route has long been recognized as the most preferred route for drug delivery as it offers high patient compliance and requires minimal expertise. Unlike small molecule drugs, the harsh environment of the gastrointestinal tract and low permeability across the intestinal epithelium make oral delivery extremely ineffective for macromolecules. Accordingly, delivery systems that are rationally constructed with suitable materials to overcome barriers to oral delivery are exceptionally promising. Among the most ideal materials are polysaccharides. Depending on the interaction between polysaccharides and proteins, the thermodynamic loading and release of proteins in the aqueous phase can be realized. Specific polysaccharides (dextran, chitosan, alginate, cellulose, etc.) endow systems with functional properties, including muco-adhesiveness, pH-responsiveness, and prevention of enzymatic degradation. Furthermore, multiple groups in polysaccharides can be modified, which gives them a variety of properties and enables them to suit specific needs. This review provides an overview of different types of polysaccharide-based nanocarriers based on different kinds of interaction forces and the influencing factors in the construction of polysaccharide-based nanocarriers. Strategies of polysaccharide-based nanocarriers to improve the bioavailability of orally administered proteins/peptides were described. Additionally, current restrictions and future trends of polysaccharide-based nanocarriers for oral delivery of proteins/peptides were also covered.

A nano-delivery system based on preventing degradation and promoting absorption to improve the oral bioavailability of insulin

Oral insulin delivery can improve patient compliance and simulate the portal-peripheral insulin concentration gradient produced by endogenous insulin, so oral insulin delivery has a broad prospect. However, some characteristics of the gastrointestinal tract, lead to low oral bioavailability. Therefore, a "ternary mutual-assist" nano-delivery system based on poly(lactide-co-glycolide) (PLGA) as the backbone combined with ionic liquids (IL) and vitamin B12-chitosan (VB12-CS) was constructed in this study, the protein protection performance of IL improves the room temperature stability of the loaded insulin during nanocarrier preparation, transportation and storage to a certain extent, and the protein protection function of IL combined with the slow degradation property of PLGA and the pH-responsive function of VB12-CS to prevent the degradation of insulin in the gastrointestinal tract. In addition, the mucosal adhesion function of VB12-CS, VB12 receptor- and clathrin-mediated transcellular transport involving VB12-CS and IL, and paracellular transport mediated by IL and CS can be combined to improve the intestinal epithelial transport efficiency of insulin, thus, the nanocarrier has stronger preventing degradation and promoting absorption effects. Pharmacodynamic studies showed that after oral administration of VB12-CS-PLGA@IL@INS NPs to diabetic mice, the blood glucose level decreased to about 13 mmol/L, below the critical point of 16.7 mmol/L, and the blood glucose reached a normal level, which was 0.4 times of the blood glucose value before administration, its relative pharmacological bioavailability was 31.8 %, higher than the general nanocarriers (10-20 %) and more beneficial to the clinical transformation of oral insulin.

Nanoprecipitates of γ-cyclodextrin/epigallocatechin-3-gallate inclusion complexes as efficient antioxidants for preservation of shrimp surimi products: synthesis, performance and mechanism

BACKGROUND

Epigallocatechin-3-gallate (EGCG) is well known for excellent chain-breaking antioxidant capability. However, browning by oxidation and aggregation of EGCG is a non-negligible defect that hinders its applications as an antioxidant in various foodstuffs. Therefore, how to eliminate or mitigate browning efficiently, while retaining functionalities as food additive is a challenge in the food industry.

RESULTS

Our results demonstrated that EGCG could be anchored within the internal cavity of γ-cyclodextrin (γ-CD) to form an inclusion structure, where hydrophobic interaction, hydrogen bonding, and π-stacking were identified to be the primary drivers. The interplay between two molecules and the steric hindrance from γ-CD could restrict the motion and aggregation of EGCG efficiently, thus alleviating the browning effect. In addition, the conformational adaption of EGCG within the inclusions would result in general decreases in hydrogen-bond dissociation enthalpies for the pyrogallol-type structure on the b ring, thus enhancing the antioxidant capability. In practical application, the nanoscale γ-CD/EGCG inclusion complexes were validated preliminarily as efficient additives in the preservation of shrimp surimi, presenting significant effects on prolonging the shelf-life of products.

CONCLUSION

Here, nanoscale γ-CD/EGCG inclusion complexes as alternatives to EGCG were tailored as food antioxidants for the preservation of shrimp surimi products, exerting antioxidant effects while mitigating the browning effects of EGCG on products. Through self-assembly, EGCG would be anchored with the cavity of γ-CD, which could regulate the release modes and restrict the aggregation of EGCG. This facile strategy has great potential in food preservation. © 2023 Society of Chemical Industry.

Biopolymeric nanocarrier: an auspicious system for oral delivery of insulin

Subcutaneous administration of insulin has been practiced for the clinical supervision of diabetes pathogenesis but it is often ineffective to imitate the glucose homeostasis and is always invasive. Therefore, it causes patient discomfort and infection of local tissue. These issues lead to finding an alternative route for insulin delivery that could be effective, promising, and non-invasive. However, delivery of insulin orally is the most suitable route but the rapid breakdown of insulin by the gastrointestinal enzymes becomes a major barrier to this method. Therefore, nanocarriers (which guard insulin against degradation and facilitate its uptake) are preferred for oral insulin delivery. Among various categories of nanocarriers, bio-polymeric nanocarriers draw special attention owing to their hydrophilic, non-toxic, and biodegradable nature. This review provides a detailed overview of insulin-loaded biopolymer-based nanocarriers, which give future direction in the optimization and development of a clinically functional formulation for their effective and safe delivery.

Natural Polysaccharide-Based Nanodrug Delivery Systems for Treatment of Diabetes

In recent years, natural polysaccharides have been considered as the ideal candidates for novel drug delivery systems because of their good biocompatibility, biodegradation, low immunogenicity, renewable source and easy modification. These natural polymers are widely used in the designing of nanocarriers, which possess wide applications in therapeutics, diagnostics, delivery and protection of bioactive compounds or drugs. A great deal of studies could be focused on developing polysaccharide nanoparticles and promoting their application in various fields, especially in biomedicine. In this review, a variety of polysaccharide-based nanocarriers were introduced, including nanoliposomes, nanoparticles, nanomicelles, nanoemulsions and nanohydrogels, focusing on the latest research progress of these nanocarriers in the treatment of diabetes and the possible strategies for further study of polysaccharide nanocarriers.

Versatile Oral Insulin Delivery Nanosystems: From Materials to Nanostructures

Diabetes is a chronic metabolic disease characterized by lack of insulin in the body leading to failure of blood glucose regulation. Diabetes patients usually need frequent insulin injections to maintain normal blood glucose levels, which is a painful administration manner. Long-term drug injection brings great physical and psychological burden to diabetic patients. In order to improve the adaptability of patients to use insulin and reduce the pain caused by injection, the development of oral insulin formulations is currently a hot and difficult topic in the field of medicine and pharmacy. Thus, oral insulin delivery is a promising and convenient administration method to relieve the patients. However, insulin as a peptide drug is prone to be degraded by digestive enzymes. In addition, insulin has strong hydrophilicity and large molecular weight and extremely low oral bioavailability. To solve these problems in clinical practice, the oral insulin delivery nanosystems were designed and constructed by rational combination of various nanomaterials and nanotechnology. Such oral nanosystems have the advantages of strong adaptability, small size, convenient processing, long-lasting pharmaceutical activity, and drug controlled-release, so it can effectively improve the oral bioavailability and efficacy of insulin. This review summarizes the basic principles and recent progress in oral delivery nanosystems for insulin, including physiological absorption barrier of oral insulin and the development of materials to nanostructures for oral insulin delivery nanosystems.

Fabrication, characterization and in vitro cell exposure study of zein-chitosan nanoparticles for co-delivery of curcumin and berberine

For the first time, we synthesized the co-delivery nanopolymers using zein protein as the core and chitosan polysaccharide as the shell to deliver curcumin (Cur) and berberine (Ber) in MDA-MB-231 breast cancer cells. It has been shown that Cur and Ber altogether have synergistic effects on multiple cancers. Herein, the curcumin-zein-berberine-chitosan (Cur-Z-Ber-Ch) nanoparticles were fabricated and their organization procedure was reported. Physicochemical properties of synthesized nanoparticles were determined by Fourier transform infrared (FTIR) spectroscopy, XRD and fluorescence spectroscopy analyses. The nanoparticles included relatively small particles (d = 168.24 nm) with +36.76 mV zeta potential. The resulting nanoparticles had high entrapment efficiency (about 75%) for Cur and 60% for Ber. The Cur-Z-Ber-Ch nanoparticles represented ideal redispersibility and storage stability after 4 months. Drug release of the freeze-dried nanoparticles had pH-sensitive characteristic. In vitro cytoxicity assay demonstrated that Cur-Z-Ber-Ch nanoparticles induced elevated cytotoxic effect in MDA-MB-231 and A549 cancer cells. In vitro studies in MDA-MB-231 cells demonstrated that the Cur-Z-Ber-Ch nanoparticles could successfully increase cellular uptake and apoptosis with significant inhibition of IL-8 pro-inflammatory cytokines in comparison to the free Cur + Ber bioactive molecules. These bio-nanoparticles are the co-delivery vehicle for Cur and Ber which could be beneficial for participating them into pharmaceutical products.

An edible kanamycin sulfate cross-linked cellulose active against multiple pathogenic bacteria

In this work, an edible cellulose-based antibacterial material was prepared by cross-linking α-cellulose and kanamycin sulfate via glutaraldehyde to form kanamycin sulfate-glutaraldehyde-cellulose. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction results indicated that the kanamycin sulfate molecule was cross-linked with the molecular chain of cellulose. The optimal mass ratio of kanamycin sulfate to α-cellulose was 1:100 and the degree of substitution reached 1.11%. The optimal kanamycin sulfate-glutaraldehyde-cellulose material showed an excellent inhabitation against both Gram-positive and Gram-negative bacteria. Meantime, the optimal kanamycin sulfate-glutaraldehyde-cellulose had a marked resistance to gastric acid and had low cell cytotoxicity. To promote the application of the kanamycin sulfate-glutaraldehyde-cellulose material, the porous microspheres were prepared via the sol-gel method. The particle size of the homogeneous porous microspheres is mainly distributed between 1.5 and 2.0 μm. Therefore, the kanamycin sulfate-glutaraldehyde-cellulose described herein is a potential edible, eco-friendly, potent, stable, inexpensive, and antibacterial carrier material for delivering drugs, proteins, or vaccines.

Evaluation of the physicochemical properties and in vitro digestibility of the complex formed between rice starch and a novel pigment from Vaccinium bracteatum Thunb. leaf

This study investigated the effect of Vaccinium bracteatum Thunb. leaf (VBTL) dark blue pigment on the physicochemical properties and in vitro digestibility of different rice starches. The results showed that glutinous rice starch (GRS) had a higher pigment loading capacity than indica rice starch (IRS) and japonica rice starch (JRS). Fourier transform infrared spectroscopy showed that these binary complexes between pigment and starch molecules bind through strong hydrogen bonds. All starch-pigment complexes displayed a lower gelatinization enthalpy than the controls. The addition of this pigment reduced the maximum starch in vitro digestion amount. Furthermore, the addition of pigment significantly increased the resistant starch and decreased the rapidly digestible starch in 'Wu mi', rice grains dyed by VBTL. This study provided important evidence of the digestion resistibility of VBTL dark blue pigment on 'Wu mi' to promote glycaemic regulation as a healthy cereal product.

Characterization of Cationic Modified Short Linear Glucan and Fabrication of Complex Nanoparticles with Low and High Methoxy Pectin

In this study, we chemically modified the short linear glucan (SLG) using the 3-chloro-2-hydroxypropyl trimethylammonium chloride to introduce a positive surface charge via cationization (CSLG). We then prepared CSLG-based binary nanocomplex particles through electrostatic interactions with low and high methoxyl pectin. The two new types of binary nanocomplex were comprehensively characterized. It was found that the nanocomplex particles showed a spherical shape with the particle size of <700 nm, smooth surface, homogeneous distribution, and negative surface charge. Fourier transform infrared spectroscopy (FTIR) revealed that the driving forces to form nanocomplex were primarily electrostatic interactions and hydrogen bonding. In addition, increasing the CSLG concentration in the nanocomplex significantly enhanced both thermal stability and digestive stability. By comparing the two complex nanoparticles, the HMP-CSLG has a larger particle size and better stability under the GI condition due to the high content of the methoxy group. Additionally, the HMP-CSLG nanoparticle has a higher encapsulation efficiency and slower release rate under simulated gastrointestinal fluid for tangeretin compared with the LMP-CSLG. These results provide new insights into designing the CSLG-based nanocomplex as a potential oral delivery system for nutraceuticals or active ingredients.

Fabrication of nanostructured multi-unit vehicle for intestinal-specific delivery and controlled release of peptide

An oral multi-unit delivery system was developed by incorporating the nanoparticle (NP) into the nanofiber mat and its efficiency for intestinal-specific delivery and controlled release of a peptide (insulin) was investigated. Initially, the influence of deacetylation degree (DD) of chitosan and ionic gelation methods on the properties of NPs was studied. High DD (95%) chitosan was attributed to higher encapsulation efficiency and stability when crosslinked with polyanion tripolyphosphate. Subsequently, the multi-unit system was fabricated using a pH-sensitive polymer (sodium alginate) as the coating layer to further encapsulate the NP. Fiber mat with an average diameter of 481 ± 47 nm could significantly decrease the burst release of insulin in acidic condition and release most amount of insulin (>60%) in the simulated intestinal medium. Furthermore, the encapsulated peptide remained in good integrity. This multi-unit carrier provides the better-designed vehicle for intestinal-specific delivery and controlled release of the peptide.

pH-Responsive Cellulose-Based Microspheres Designed as an Effective Oral Delivery System for Insulin

Functional modified cellulose microsphere (CMs) materials exhibit great application potential in drug various fields. Here, we designed pH-responsive carboxylated cellulose microspheres (CCMs) by the citric/hydrochloric acid hydrolysis method to enhance oral bioavailability of insulin by a green route. The CMs were high purity cellulose that dissolved and regenerated from a green solvent by the green sol-gel method. The prepared microspheres were characterized by spectroscopic techniques, such as field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectrum (FT-IR), X-ray diffraction (XPS), etc. The spherical porous structure and carboxylation of cellulose were confirmed by FESEM and FT-IR, respectively. Insulin was loaded into the CCMs by electrostatic interactions, and the insulin release was controlled through ionization of carboxyl groups and proton balance. In vitro insulin release profiles demonstrated the suppression of insulin release in artificial gastric fluid (AGF), while a significant increase at artificial intestinal fluid (AIF) was observed. The insulin release profile was fitted in Korsmeyer-Peppas kinetic model, and insulin release was governed by the Fickian diffusion mechanism. The stability of the secondary structure of insulin was studied by dichroism circular. Excellent biocompatibility and no cytotoxicity of designed CCMs cast them as a potential oral insulin carrier.

Starch nanoparticles prepared by enzymatic hydrolysis and self-assembly of short-chain glucans

Enzymatic hydrolysis and self-assembly are considered promising methods for preparation of starch nanoparticles (SNPs) because they are environmentally friendly, and time- and cost-effective. These methods are based on the self-assembly of short-chain glucans released from the α-1,6 bonds in amylopectin. Since their discovery, many studies have described the structural and physicochemical properties of self-assembled SNPs. Self-assembled SNPs can be prepared by two methods: using only the soluble portion containing the short-chain glucans, or using the whole hydrolyzate including both insoluble and soluble fractions. Although the structural and physical properties of self-assembled SNPs can be attributed to the composition of the hydrolyzates that participate in self-assembly, this aspect has not yet been discussed. This review focuses on SNPs self-assembled with only soluble short-chain glucans and addresses their characteristics, including formation mechanisms as well as structural and physicochemical properties, compared with SNPs prepared with total hydrolyzates.

Core-Shell Biopolymer Nanoparticles for Co-Delivery of Curcumin and Piperine: Sequential Electrostatic Deposition of Hyaluronic Acid and Chitosan Shells on the Zein Core

Curcumin and piperine are natural nutraceuticals that exhibit synergistic biological activities, but have different polarities, which can make their encapsulation within a single delivery system challenging. In this study, the two bioactive components were encapsulated within core-shell nanoparticles formed by a combination of antisolvent precipitation and layer-by-layer deposition. Initially, strongly hydrophobic curcumin (log P = 4.12) was embedded in the hydrophobic core of zein-hyaluronic acid nanoparticles using the antisolvent precipitation method. Then, the weakly hydrophobic piperine (log P = 2.78) was adsorbed to the outer biopolymer shell of these nanoparticles. Finally, the nutraceutical-loaded particles were coated with a layer of chitosan by the electrostatic deposition method. The surface charge and coating thickness depended on the number of adsorbed layers and the nature of the outer layer, being negative for hyaluronic acid and positive for chitosan. Low-, medium-, and high-molecular weight chitosan were utilized to modify the surface properties. Chitosan with a low-molecular weight was selected to fabricate the core-shell nanoparticles because it produced small highly charged cationic particles (d = 599 nm; ζ = +38.1 mV). The encapsulation efficiency and loading capacities were 90.4 and 5.7% for curcumin, and 86.4 and 5.4% for piperine, respectively. The core-shell nanoparticles protected the nutraceuticals from chemical degradation during light exposure, thermal processing, and storage for 2 months. Moreover, the nanoparticles were able to control the release of the bioactive components in simulated gastrointestinal conditions. Our results should facilitate the development of more effective nanodelivery systems for nutraceuticals that exhibit synergistic activities, but have different molecular characteristics.

Formation of Nanocomplexes between Carboxymethyl Inulin and Bovine Serum Albumin via pH-Induced Electrostatic Interaction

As a functional polysaccharide, inulin was carboxymethylated and it formed nanocomplexes with bovine serum albumin (BSA). The success of obtaining carboxymethyl inulin (CMI) was confirmed by a combination of Fourier transform Infrared (FT-IR), Raman spectroscopy, gel permeation chromatography (GPC), and titration. The effects of pH and ionic strength on the formation of CMI/BSA nanocomplexes were investigated. Our results showed that the formation of complex coacervate (pHφ1) and dissolution of CMI/BSA insoluble complexes (pHφ2) appeared in pH near 4.85 and 2.00 respectively. FT-IR and Raman data confirmed the existence of electrostatic interaction and hydrogen bonding between CMI and BSA. The isothermal titration calorimetry (ITC) results suggested that the process of complex formation was spontaneous and exothermic. The complexation was dominated by enthalpy changes (∆Η < 0, ∆S < 0) at pH 4.00, while it was contributed by enthalpic and entropic changes (∆Η < 0, ∆S > 0) at pH 2.60. Irregularly shaped insoluble complexes and globular soluble nanocomplexes (about 150 nm) were observed in CMI/BSA complexes at pH 4.00 and 2.60 while using optical microscopy and atomic force microscopy, respectively. The sodium chloride suppression effect on CMI/BSA complexes was confirmed by the decrease of incipient pH for soluble complex formation (or pHc) and pHφ1 under different sodium chloride concentrations. This research presents a new functional system with the potential for delivering bioactive food ingredients.

Characterization of Cationic Modified Debranched Starch and Formation of Complex Nanoparticles with κ-Carrageenan and Low Methoxyl Pectin

The functional modifications of debranched starch (DBS) has been attracting the interest of researchers. This study marks the first time that DBS was modified by cationization through the use of (3-chloro-2-hydroxypropyl) trimethylammonium chloride with the introduction of cationic functional groups. The physicochemical properties and structural characteristics of cationized debranched starch (CDBS) were systematically assessed. The results demonstrate that the maximum degree of substitution (DS) value obtained was as high as 1.14, and the corresponding CDBS exhibited significantly higher zeta potential values: approximately +35 mV. The minimal inhibitory concentration values of the CDBS of DS 1.14 against Escherichia coli and Staphylococcus aureus were 6 and 8 mg mL^-1, respectively. In addition, nanoparticles were successfully prepared with a combination of CDBS and low methoxyl pectin (LMP) and a combination of CDBS and κ-carrageenan (CRG). The maximum encapsulation efficiency of nanoparticles for (-)-epigallocatechingallate can reach 87.8%.

Novel Approach with Controlled Nucleation and Growth for Green Synthesis of Size-Controlled Cyclodextrin-Based Metal-Organic Frameworks Based on Short-Chain Starch Nanoparticles

In this study, the nano- and microsized cyclodextrin-based metal-organic frameworks (CD-MOFs) were successfully conducted using short-chain starch nanoparticles as seeds through the seed-mediated method. The morphology, size, crystal structure, thermal, and N₂ adsorption properties of CD-MOFs prepared at different time intervals were investigated. The scanning electron microscopy results showed that the size variation from nanometer to millimeter could be controlled by crystal growth time. The CD-MOFs based on short-chain starch nanoparticle had higher crystallinity and N₂ uptake, thus indicating that the method of seed-mediated was more facile and efficient than the previous approach. Resveratrol (Res) is a natural polyphenol compound that has anticancer and antimicrobial activities against several pathogens. However, this compound suffers from poor stability. trans-Res rapidly isomerizes when exposed under ultraviolet or visible light. The results showed that the stability of Res was substantially enhanced by its encapsulation in CD-MOF crystals.

Preparation and Characterization of Insulin-Loaded Zein/Carboxymethylated Short-Chain Amylose Complex Nanoparticles

In this work, we use antisolvent precipitation to prepare zein/carboxymethylated short-chain amylose (CSA) complex nanoparticles for insulin encapsulation, showing that insulin-loaded zein/CSA complex nanoparticles are homogeneous, generally exhibiting sizes of <200 nm with a narrow distribution (polydispersity index < 0.100), spherical shape, and strong negative charge (-40 mV). Fourier transform infrared spectroscopy analysis reveals that the formation of the above nanoparticles is mainly driven by hydrophobic, hydrogen-bonding, and electrostatic interactions between CSA, insulin, and zein. In comparison to zein nanoparticles, zein/CSA complex nanoparticles feature much higher insulin encapsulation efficiency (45.8 versus 90.5%, respectively) and are essentially nontoxic to Caco-2 cells. Thus, this work provides new insights into the design of drug delivery systems and is expected to inspire their further development.

Recent advances of polysaccharide-based nanoparticles for oral insulin delivery

Diabetes mellitus is a highly prevalent metabolic and chronic disease affecting millions of people in the world. The most common route of insulin therapy is the subcutaneous injection due to its low bioavailability and enzymatic degradation. The search for effective and high patient compliance insulin delivery systems has been a major challenge over many decades. The polysaccharide-based nanoparticles as delivery vehicles for insulin oral administration have recently attracted substantial interests. The present review highlights the recent advances on the development of nanoparticles prepared from polysaccharides, including chitosan, alginate, dextran and glucan, for oral delivery of insulin, overcoming multiple barriers in gastrointestinal tract. The aims of this review are first to summarize the strategies that have been applied in the past 5 years to fabricate polysaccharide-based nanoparticles for insulin oral delivery, and then to provide in-depth understanding on the mechanisms by which such nanoparticles protect insulin against degradation in the digestive tract and provide sustained release to enhance mucus permeation and transepithelial transport of insulin administered via oral route.

Development of Functional or Medical Foods for Oral Administration of Insulin for Diabetes Treatment: Gastroprotective Edible Microgels

Insulin and an antacid [Mg(OH)₂] were co-encapsulated inside calcium alginate microgels (diameter = 280 μm) using a vibrating nozzle injector. Confocal microscopy indicated that insulin was successfully encapsulated inside the microgels and remained inside them after they were exposed to simulated gastric conditions. Localized fluorescence intensity measurements indicated that the internal pH of the antacid-loaded microgels was around pH 7.4 after incubation in acidic gastric fluids but below the limit of detection (pH < 4) in the antacid-free microgels. After incubation in small intestine conditions, around 30% of the insulin was released from the antacid-loaded microgels over a 2 h period. Encapsulation of insulin within the antacid-loaded microgels increased its biological activity after exposure to simulated gastric conditions. In particular, the encapsulated insulin significantly increased Akt phosphorylation at both Thr308 and Ser473 in L6 myotubes when compared to free insulin.

Green Synthesis of Cyclodextrin-Based Metal-Organic Frameworks through the Seed-Mediated Method for the Encapsulation of Hydrophobic Molecules

Metal-organic frameworks (MOFs) are attracting considerable attention as a result of their unique structural properties, such as a high surface area, highly porous topology, and tunable size and shape, which enable them to have potential applications as a new class of carriers for functional agent or drug delivery. However, most of the MOFs and the polymers used are not pharmaceutically acceptable. For the first time, this study successfully conducted the rapid synthesis of cyclodextrin metal-organic frameworks (CD-MOFs) through a facile and green seed-mediated method. The size control, crystal structure, and thermal properties of CD-MOFs with and without seeds were investigated. When 1 mg/mL seed was added, the size of γ-CD-MOF crystals decreased from 6.2 ± 0.8 to 1.8 ± 0.4 μm. The CD-MOFs synthesized though the seed-mediated method had higher crystallinity and thermal stability than those that were not. Furthermore, the CD-MOFs could encapsulate hydrophobic molecules, such as Nile red (NR), which was chosen as a model, and the interaction mechanism between γ-CD-MOFs and NR was investigated. Results showed the formation of a 1:1 complex between NR and CD-MOFs, demonstrating the potential of these polymers as carriers for hydrophobic drug delivery applications.

Fabrication and characterization of complex nanoparticles based on carboxymethyl short chain amylose and chitosan by ionic gelation

The combination of carboxymethyl short chain amylose with chitosan could be considered as a candidate for oral delivery of insulin.

Oral insulin delivery: existing barriers and current counter-strategies

Objectives

The chronic and progressive nature of diabetes is usually associated with micro- and macrovascular complications where failure of pancreatic β-cell function and a general condition of hyperglycaemia is created. One possible factor is failure of the patient to comply with and adhere to the prescribed insulin due to the inconvenient administration route. This review summarizes the rationale for oral insulin administration, existing barriers and some counter-strategies trialled.

Key findings

Oral insulin mimics the physiology of endogenous insulin secreted by pancreas. Following the intestinal absorption of oral insulin, it reaches the liver at high concentration via the portal vein. Oral insulin on the other hand has the potential to protect pancreatic β-cells from autoimmune destruction. Structural modification, targeting a particular tissue/receptor, and the use of innovative pharmaceutical formulations such as nanoparticles represent strategies introduced to improve oral insulin bioavailability. They showed promising results in overcoming the hurdles facing oral insulin delivery, although delivery is far from ideal.

Summary

The use of advanced pharmaceutical technologies and further research in particulate carrier system delivery predominantly nanoparticle utilization would offer useful tools in delivering insulin via the oral route which in turn would potentially improve diabetic patient compliance to insulin and the overall management of diabetes.