Surface functional modification of self-assembled insulin nanospheres for improving intestinal absorption

Self-Assembled Polymers for Gastrointestinal Tract Targeted Delivery through the Oral Route: An Update

Gastrointestinal tract (GIT) targeted drug delivery systems have gained growing attention as potential carriers for the treatment of different diseases, especially local colonic diseases. They have lower side effects as well as enhanced oral delivery efficiency because of various therapeutics that are vulnerable to acidic and enzymatic degradation in the upper GIT are protected. The novel and unique design of self-assembled nanostructures, such as micelles, hydrogels, and liposomes, which can both respond to external stimuli and be further modified, making them ideal for specific, targeted medical needs and localized drug delivery treatments through the oral route. Therefore, the aim of this review was to summarize and critically discuss the pharmaceutical significance and therapeutic feasibility of a wide range of natural and synthetic biomaterials for efficient drug targeting to GIT using the self-assembly method. Among various types of biomaterials, natural and synthetic polymer-based nanostructures have shown promising targeting potential due to their innate pH responsiveness, sustained and controlled release characteristics, and microbial degradation in the GIT that releases the encapsulated drug moieties.

Alginate as a Promising Biopolymer in Drug Delivery and Wound Healing: A Review of the State-of-the-Art

Biopolymeric nanoparticulate systems hold favorable carrier properties for active delivery. The enhancement in the research interest in alginate formulations in biomedical and pharmaceutical research, owing to its biodegradable, biocompatible, and bioadhesive characteristics, reiterates its future use as an efficient drug delivery matrix. Alginates, obtained from natural sources, are the colloidal polysaccharide group, which are water-soluble, non-toxic, and non-irritant. These are linear copolymeric blocks of α-(1→4)-linked l-guluronic acid (G) and β-(1→4)-linked d-mannuronic acid (M) residues. Owing to the monosaccharide sequencing and the enzymatically governed reactions, alginates are well-known as an essential bio-polymer group for multifarious biomedical implementations. Additionally, alginate’s bio-adhesive property makes it significant in the pharmaceutical industry. Alginate has shown immense potential in wound healing and drug delivery applications to date because its gel-forming ability maintains the structural resemblance to the extracellular matrices in tissues and can be altered to perform numerous crucial functions. The initial section of this review will deliver a perception of the extraction source and alginate’s remarkable properties. Furthermore, we have aspired to discuss the current literature on alginate utilization as a biopolymeric carrier for drug delivery through numerous administration routes. Finally, the latest investigations on alginate composite utilization in wound healing are addressed.

Biodegradable phenylboronic acid-modified ε-polylysine for glucose-responsive insulin delivery via transdermal microneedles

Microneedles with insulin-loaded glucose-responsive particles are promising to control the blood glucose levels of diabetic patients. In particular, the long-term usage of these microneedles calls for biodegradable and cost-effective particles, which are still large challenges. In this paper, glucose-responsive 4-carboxy-3-fluorophenylboronic acid-grafted ε-polylysine (CFPBA-g-PL) was synthesized to meet these requirements. CFPBA-g-PL had low cytotoxicity, good hemocompatibility and no tissue reaction. The pharmacokinetics of CFPBA-g-PL were also studied. The self-assembled particles of CFPBA-g-PL were prepared via simple ultrasonic treatment. The insulin-loaded particles of CFPBA-g-PL (named INS/GRP-12.8) presented a glucose-responsive insulin delivery performance based on the disassembly-related mechanism in vitro. The INS/GRP-12.8-encapsulated microneedle patch with a uniform morphology and moderate skin penetration performance was prepared via a molding strategy. INS/GRP-12.8 lasted for more than 8 hours of normoglycemia on STZ-induced diabetic SD rats via subcutaneous injection and the INS/GRP-12.8-encapsulated microneedle patch also showed a blood-glucose-level-lowering performance in vivo via transdermal administration.

The immunogenic reaction and bone defect repair function of ε-poly-L-lysine (EPL)-coated nanoscale PCL/HA scaffold in rabbit calvarial bone defect

Tissue engineering is a promising strategy for bone tissue defect reconstruction. Immunogenic reaction, which was induced by scaffolds degradation or contaminating microorganism, influence cellular activity, compromise the efficiency of tissue engineering, or eventually lead to the failure of regeneration. Inhibiting excessive immune response through modulating scaffold is critical important to promote tissue regeneration. Our previous study showed that ε-poly-L-lysine (EPL)-coated nanoscale polycaprolactone/hydroxyapatite (EPL/PCL/HA) composite scaffold has enhanced antibacterial and osteogenic properties in vitro. However, the bone defect repair function and immunogenic reaction of EPL/PCL/HA scaffolds in vivo remains unclear. In the present study, three nanoscale scaffolds (EPL/PCL/HA, PCL and PCL/HA) were transplanted into rabbit paraspinal muscle pouches, and T helper type 1 (Th1), T helper type 2 (Th2), T helper type 17 (Th17), and macrophage infiltration were analyzed after 1 week and 2 weeks to detect their immunogenic reaction. Then, the different scaffolds were transplanted into rabbit calvarial bone defect to compare the bone defect repair capacities. The results showed that EPL/PCL/HA composite scaffolds decreased pro-inflammatory Th1, Th17, and type I macrophage infiltration from 1 to 2 weeks, and increased anti-inflammatory Th2 infiltration into the regenerated area at 2 weeks in vivo, when compared to PCL and PCL/HA. In addition, EPL/PCL/HA showed an enhanced bone repair capacity compared to PCL and PCL/HA when transplanted into rabbit calvarial bone defects at both 4 and 8 weeks. Hence, our results suggest that EPL could regulate the immunogenic reaction and promote bone defect repair function of PCL/HA, which is a promising agent for tissue engineering scaffold modulation.

Phospholipid complex based nanoemulsion system for oral insulin delivery: preparation, in vitro, and in vivo evaluations

Purpose: The aim of this research was to develop a phospholipid complex based nanoemulsion system for oral insulin delivery.

Methods: Insulin-phospholipid complex (IPC) was firstly prepared by an anhydrous co-solvent lyophilization method, and then encapsulated into the oil phase of nanoemulsion to obtain the IPC-based nanoemulsion (IPC-NE). Both water-in-oil (W/O) IPC-NE and oil-in-water (O/W) IPC-NE were formulated and evaluated for comparison.

Results: The obtained W/O IPC-NE and O/W IPC-NE were both spherical in shape with a mean particle size of 18.6±0.79 nm and 27.3±1.25 nm, respectively. While both IPC-NEs exhibited enhanced Caco-2 cell monolayers permeability than IPC and insulin solution, W/O IPC-NE showed relatively greater protective effects against enzymatic degradation than O/W IPC-NE. Moreover, oral administration of W/O IPC-NE exhibited significant hypoglycemic effects, with 12.4-fold and 1.5-fold higher oral bioavailability compared with insulin solution and O/W IPC-NE, respectively.

Conclusion: IPC-NEs, especially the W/O IPC-NE showed promising efficiency in vitro and in vivo, thus could be a potential strategy for oral insulin delivery.

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.

Selenium nanoparticles as versatile carriers for oral delivery of insulin: Insight into the synergic antidiabetic effect and mechanism

Oral insulin delivery has been plagued by limited bioavailability. This work reports selenium nanoparticles (SeNPs) for oral insulin delivery to overcome the absorption barrier. Insulin-loaded SeNPs (INS-SeNPs) were fabricated by ionic cross-linking/in situ reduction and characterized by particle size and drug entrapment. The resultant INS-SeNPs were 120nm around in particle size with high drug loading. INS-SeNPs exhibited controllable insulin release and outstanding stability in the digestive fluids. INS-SeNPs caused a significant hypoglycemic effect in both normal and diabetic rats. The pharmacological bioavailability was up to 9.15% relative to subcutaneous insulin. Likewise, the blood insulin evidently increased in terms of INS-SeNPs. Ex vivo intestinal imaging and cell experiments showed the excellent performance of INS-SeNPs in intestinal permeability. INS-SeNPs could alleviate oxidative stress, improve pancreatic islet function, and promote glucose utilization. Our study provides proof of concept for using SeNPs to orally deliver insulin, jointly potentiating the antidiabetic effect.

Catalase-only nanoparticles prepared by shear alone: Characteristics, activity and stability evaluation

Catalase is a promising therapeutic enzyme; however, it carries risks of inactivation and rapid degradation when it is used in practical bioprocess, such as delivery in vivo. To overcome the issue, we made catalase-only nanoparticles using shear stress alone at a moderate shear rate of 217s(-1) in a coaxial cylinder flow cell. Properties of nanoparticles, including particle size, polydispersity index and zeta potential, were characterized. The conformational changes of pre- and post-sheared catalase were determined using spectroscopy techniques. The results indicated that the conformational changes of catalase and reduction in α-helical content caused by shear alone were less significant than that by desolvation method. Catalase-only nanoparticles prepared by single shear retained over 90% of its initial activity when compared with the native catalase. Catalase nanoparticles lost only 20% of the activity when stored in phosphate buffer solution for 72h at 4°C, whereas native catalase lost 53% under the same condition. Especially, the activity of nanogranulated catalase was decreased only slightly in the simulated intestinal fluid containing α-chymotrypsin during 4h incubation at 37°C, implying that the catalase nanoparticle was more resistant to the degradation of proteases than native catalase molecules. Overall, catalase-only nanoparticles offered a great potential to stabilize enzymes for various pharmaceutical applications.