INTRODUCTION:

Aquasomes are a novel class of nanoparticulate carrier systems that have gained significant attention in the field of drug delivery due to their unique properties and versatile applications. They are characterized by their ability to carry and deliver bioactive molecules, such as proteins, peptides, genes, and vaccines, while preserving their biological activity and structural integrity. Aquasomes are nanoparticulate carrier systems; however, they are three-layered self-assembled structures rather than simple nanoparticles. They are made of a solid phase nanocrystalline core covered in an oligomeric film, onto which biochemically active molecules are adsorbed, either completely or partially. The water-like characteristics of aquasomes, which resemble "bodies of water," protect and preserve delicate biological molecules. This ability to maintain conformational integrity while allowing for a high degree of surface exposure is used to target bioactive molecules, such as peptide and protein hormones, enzymes, antigens, and genes, to particular locations. These three-layered structures self-assemble by ionic and non-covalent bonding. These ceramic nanoparticles that stabilize carbohydrates are referred to as "aquasomes“.

The molecule with pharmacological activity that is added to pre-formed nanoparticles' carbohydrate surface through co-polymerization, diffusion, or adsorption. A principle from food chemistry, biophysics, and microbiology is combined with numerous findings about aquasomes, such as solid phase synthesis, supra molecular chemistry, molecular shape modification, and self assembly. The "Somes" are the innovative drugs delivery systems that resemble cells. A polyhydroxyl oligomeric layer covers the particle core of Aquasomes (Carbohydrates-ceramic nanoparticles), a form of nano biopharmaceutical carrier system. The particle core is made of nanocrystalline calcium phosphate or ceramic diamond. An alternative term for aquasomes is "bodies of water." It functions as an effective carrier system transporting bioactive molecules such as peptides, proteins, hormones, antigens, and genes to certain places because of its characteristics, which include surface exposure, conformational integrity, and protection and preservation of delicate biological molecules. These carbohydrates stabilize the "aquasomes," which are ceramic nanoparticles. which Nir Kossovsky initially developed. The chemical with pharmacological activity that is added to the carbohydrate surface of pre-formed nanoparticles through co-polymerization, diffusion, or adsorption.¹

Aqueous particles range in size from 60 to 300nm. Aquasome development primarily uses three types of core materials: brushite (calcium phosphate dihydrate), nanocrystalline carbon ceramics (diamonds), and tin oxide. For drugs with issues such distribution routes, chemical and physical instability, low absorption, and strong side effects, aquasomes present an appealing delivery option.

Principle of Self Assembly:

It is implied by the term "self assembly" that the individual components of a finished good take on structural orientations in two or three dimensions on their own. Three primary physicochemical processes govern the self-assembly of macromolecules in an aqueous environment, which can be utilized for the creation of smart nanostructure materials or in naturally occurring biochemistry. These processes are charged group interactions, dehydration effects, and structural stability.²

Interaction between Charged Groups:

The long-range approach of self-assembly sub units is facilitated by the interaction of charged groups, such as amino, carboxyl, sulphate, and phosphate groups. Additionally, folded proteins' tertiary structures are stabilized by charged groups.

Hydrogen Bonding and Dehydration Effect:

Alpha helices and beta sheets, both forms of secondary protein structures, are stabilized and base pair matched with the aid of hydrogen bonds. Hydrophilic molecules that form hydrogen bonds provide the surrounding water molecules with a lot of order. When it comes to molecules that are hydrophobic, meaning they cannot form hydrogen bonds. On the other hand, their propensity to reject water aids in the moiety's organization in relation to its surroundings. The overall degree of disorder/entropy of the surrounding medium is reduced by the ordered water. Organized water loses water or dehydrates and self-assembles because it is thermodynamically unfavorable.

Structural Stability:

A dipole moment is exhibited by molecules with a lower charge than formally charged groups. Van der Waals forces are the forces connected to dipoles. Van der Waals forces, which are mostly internal to the molecule, and the interaction between charged groups and hydrogen bonds, which are mostly external to the molecule, determine the structural stability of proteins in biological environments. The slight but crucial function that the Vander Waals forces play in preserving molecule shape or conformation during self-assembly is mostly felt by hydrophobic molecular areas that are protected from water.

The van der Waals forces are mostly in charge of a molecule's hardness or softness. The hydrophobic side chain's van der Waals interaction enhances the stability of compact helix structures that are not favorable to enlarged random coils thermodynamically. Successful antigen-antibody interactions depend on the maintenance of internal secondary structures, like as helices, which provide the material enough softness and permit conformational maintenance during self-assembly. These minute modifications are essential. This can result in changed biological activity and molecular function in biotechnological self-assembly. Van der Waals must therefore be buffered in order to preserve the ideal biological activity. Sugars aid in the molecular plasticization of aquasomes.³

Applications in Drug Delivery:⁴

Protein and Peptide Delivery: Aquasomes are particularly useful for delivering proteins and peptides, which are often unstable and susceptible to degradation. The carbohydrate coating on aquasomes helps protect these molecules, ensuring they reach their target site in an active form.

Gene Therapy: Aquasomes can be used to deliver genetic material, such as DNA or RNA, for gene therapy applications. Their ability to protect and stabilize nucleic acids makes them promising carriers for treating genetic disorders.

Vaccine Delivery: The stability and preservation properties of aquasomes make them ideal for vaccine delivery. They can encapsulate antigens and adjuvants, enhancing the immune response and providing prolonged protection against infectious diseases.

Cancer Therapy: Targeted delivery of anticancer drugs using aquasomes can improve the efficacy of chemotherapy while minimizing side effects. The ability to modify the surface of aquasomes with targeting ligands allows for specific delivery to tumor cells.

Demerits:

By modifying their surface using a combination of targeted molecular shielding, controlled release of drugs, and particular targeting, it is possible to regulate the release of drugs from aquasomes.

Objectives:⁵

Aquasomes shield bioactive substances. Numerous alternative carriers, including as prodrugs and liposomes, are used; nevertheless, they are susceptible to harmful interactions between the drug and the carrier. In these situations, aquasomes prove to be a suitable carrier, and the carbohydrate coating stops harmful denaturing interactions between the drug and solid carriers.

Aquasomes maintains molecular confirmation and optimum pharmacological activity. Normally, active molecules possess following qualities i.e., a unique three-dimensional conformation, a freedom of internal molecular rearrangement induced by molecular interactions and a freedom of bulk movement but proteins undergo irreversible denaturation when desiccated, even unstable in aqueous state. In the aqueous state pH, temperature, solvents, salts cause denaturation. Hence, bio-active faces many biophysical constrain. In such case, aquasomes with natural stabilizers like various polyhydroxy sugars act as dehydroprotectant maintains water like state thereby preserves molecules in dry solid state.1

Rationale:

The water-like characteristics of aquasomes protect and preserve delicate biological molecules. This property, which allows for a high degree of surface exposure and conformational integrity, is used to direct bioactive molecules, such as peptide and protein hormones, enzymes, antigens, and genes, to specific locations.⁶

Properties:⁷

Aquasomes can efficiently load huge amounts of agents using ionic, non-covalent, van der Waals, and entropic forces due to their vast size and active surface. Solid particles with colloidal physical properties that are dispersed across an aqueous medium are known as colloids.

The aquasomes' mode of action is regulated by their surface chemical. Targeted delivery, molecule shielding, and a gradual release mechanism are the three ways that aquasomes distribute material.

The aquatic-matching characteristics of aquasomes offer a medium for preserving the biochemical stability and bio-active conformational integrity. Aquasomes are resistant to degradation by other environmental factors due to their size and structural integrity, as well as their resistance to clearance by the reticuloendothelial system. Six Colloidal range biodegradable nanoparticles, or aquasomes, are the drug delivery vehicle; this allows the drug to be more concentrated in the liver and muscles. The drug may not have any trouble recognizing the receptor on the active site since it is adsorbed onto the system's surface without undergoing any surface alteration, allowing for the quick achievement of the pharmacological or biological activity. The calcium phosphate in a typical system is a biodegradable ceramic.

Monocytes and multicellular cells called osteoclasts are mostly in charge of the biodegradation of ceramic in vivo because they initiate the inflammatory response at the biomaterial implantation site. Two types of phagocytosis have been described in response to biomaterial: either the calcium phosphate crystals are taken up by the cells and dissolve in the cytoplasm when the phagosome membrane disappears, or they dissolve following the formation of heterophagosomes.

The phagocytosis of calcium phosphate was accompanied by the accumulation of residual bodies within the cell and autophagy.⁸

Aquasomes Fate:⁹

Aquasomes use biodegradable, colloidal-range nanoparticles as their drug delivery medium, which allows the medicine to be more concentrated in the muscles and liver. The medication may not have any trouble recognizing the receptor on the active site since it is adsorbed onto the system's surface without undergoing any surface alteration, allowing for the quick achievement of the pharmacological or biological activity. The Ca3(PO4)2 is a biodegradable ceramic in a typical setup. In vivo biodegradation of ceramic is mostly accomplished by monocytes and osteoclasts, which are multicellular cells. When cells come into touch with biomaterial, two different forms of phagocytosis have been identified.

a) After the phagosome membrane vanished, Ca₃(PO₄)₂ crystals were taken up alone and dissolved in the cytoplasm;

b) dissolution followed the development of heterophagosomes.

Composition of Aquasomes:¹⁰

Core material: Polymers and ceramics are common core materials. Ceramics that are crystalline, simple to make, inexpensive, biocompatible, and naturally biodegradable include tin oxide, diamond particles, and brushite (calcium phosphate). It offers a high level of structural regularity and order. Higher surface energy is produced as a result of the high degree of order, and this enables effective carbohydrate binding. These characteristics make it a strong contender for the formulation of an aquasome. There is utilization of polymers like acrylate, gelatin, and albumin.

Coating material: Commonly utilized coating materials include cellobiose, citrate, trehalose, sucrose, chitosan, and pyridoxal 5 phosphate. Carbohydrate is favored since it is a natural stabilizer and serves an important role. Adsorbed as a glassy layer in the nanometer size range, carbohydrates coat the calcium phosphate dihydrate particles that self-assemble and the preformed ceramic nanoparticles (colloidal precipitation). The types of carbohydrates utilized for this are as.

Cellobiose: This reducing sugar is 4-O-beta-D-glucopyranosyl-D-glucopyranose. It is obtained from cellulose's partial hydrolysis. It guards the drug molecule from being dehydrated.

Trehalose: This non-reducing sugar is an alpha-D-glucopuyranosyl-alpha-D-glucopyranoside.

Additionally, trehalose protects the drug molecule from denaturation and dehydration. It has been found to be more successful than cellobiose.

Bio-active molecules: Aquasomes have shown to be an excellent fit for drugs with the ability to interact with films through ionic and non-covalent interactions. Carbohydrate is one of the three layers of aquasomes that satisfies the aquasomal goal. When proteins get dehydrated, their watery structure is preserved because the hydroxyl groups on carbohydrates interact with the polar and charged groups of proteins in the same way that they do with water.

Methods of preparation of Aquasomes:¹¹

There are three steps of preparation of Aquasomes:

Preparation of core

Carbohydrate coating

Immobilization of drug

Preparation of Core:

The creation of the ceramic core is the first step in the preparation of aquasomes. Depending on the materials chosen, cores can be created using a variety of techniques, such as inverted magnetron sputtering, plasma condensation, colloidal precipitation and sonication, and other methods. Since ceramics are the most regular materials known in terms of structure, any surface modification will have a limited effect on the nature of the atoms below the surface layer, preserving the bulk properties of the ceramic. A high surface will exhibit a high level of surface energy, which will favor the binding of poly hydroxy oligomeric surfacefilm.

Two ceramic cores that are most often used are diamond and calcium phosphate. The equation for the reaction is as follows;

2Na₂HPO₄ + 3CaCl₂ + H₂O→

Ca₃ (PO₄)₂ + 4NaCl+ 2H₂ + Cl₂ + (O)

Carbohydrate Coating:

It is the second phase in the aquasome preparation process. It entails covering ceramic cores with a carbohydrate layer. The carbohydrate (polyhydroxy oligomers) coating can adsorb epitaxially on the surface of the nano-crystalline ceramic cores by a variety of methods. To encourage the nearly irreversible adsorption of carbohydrates onto the ceramic surfaces, the procedures typically involve adding polyhydroxy oligomer to a dispersion of finely cleaned ceramics in ultra pure water, sonicating the mixture, and then lyophilizing the mixture. Stir cell ultra-filtration is used to remove excess and quickly desorbing carbohydrates. The coating materials that are frequently utilized include trehalose, cellobiose, citrate, pyridoxal-5-phosphate, and sucrose.

Immobilization of Drug:

Partial adsorption is one way to load the drug into aquasomes. The solid phase for a wide spectrum of biochemically active molecules' subsequent non-denaturing self-assembly is provided by the surface-modified nanocrystalline cores.¹²

Characterization:

The main characteristics of aquasomes are their particle size distribution, drugloading capability, and structural and morphological characteristics.

Characterization of Ceramic Core Size Distribution. For Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) are commonly employed for morphological characterisation and size distribution analysis. These methods are used to examine core, coated core, and drug-loaded aquasomes. Photo correlation spectroscopy is another tool that can be used to estimate the mean particle size and zeta potential of the particles.

Structural Analysis:

Structure analysis can be done with FT-IR spectroscopy. The core and coated core can be examined using the potassium bromide sample disk method by taking an IR spectrum in the 4000–400 cm–1 wave number band. The distinctive peaks found in the spectrum are then compared to reference peaks.

The sample can also be analyzed using FT-IR to confirm the identification of the drug and sugar put over the ceramic core.

Crystallinity:

Using x-ray diffraction, the created ceramic core can be examined to determine if it behaves crystalline or amorphously. Using this method, interpretations are formed by comparing the sample's x-ray diffraction pattern to a standard diffractogram.

Characterization of Coated Core:¹³

Carbohydrate Coating.

The amount of sugar coated over the ceramic core can be measured using the concanavalin A-induced aggregation method, or the residual sugar unbound or residual sugar left after coating can be determined using the anthrone method. Moreover, zeta potential testing can verify the adsorption of sugar across the core.

Glass transition temperature:

DSC can be used to analyze the effect of carbohydrate on the drug loaded to aquasomes. DSC studies have been extensively used to study glass transition temperature of carbohydrates and proteins. The transition from glass to rubber state can be measured using a DSC analyzer as a change in temperature upon melting of glass.

Characterization of Drug-Loaded Aquasomes Drug Payload.¹⁴

The basic aquasome formulation (i.e., without drug) can be incubated for 24hours at 4°C in a known concentration of the drug solution to determine the drug loading. After that, the supernatant is separated in a chilled centrifuge using high-speed centrifugation for an hour at a low temperature. Any appropriate analysis technique can be used to quantify the amount of medication that remains in the liquid supernatant after loading.

In Vitro Drug Release Studies:

The By incubating a known quantity of the loaded medication, the in vitro release kinetics of the drug are evaluated in order to examine the release pattern of drug from the aquasomes.

Drug-loaded aquasomes continuously stirred at 37°C in a pH-appropriate buffer. Periodically, samples are taken out and centrifuged quickly for predetermined periods of time. After every withdrawal, the medium needs to be replenished in equal amounts. The amount of medication released from the supernatants is then determined using any appropriate technique. studies of in-process stability. When the aquasomes are being created, the stability and integrity of the protein can be assessed using SDS-PAGE.Thirteen.

Applications¹⁵

Insulin delivery: Cherian et al. developed aquasomes with a ceramic calcium phosphate core for injectable insulin administration. Its core was encased in disaccharides such as trehalose, cellobiose, and pyridoxal-5-phosphate. After that, an adsorption procedure was used to apply its drugs to these particles. The in vivo performance of several aquasome insulin formulations was tested in albino rats. Every formulation produced a prolonged decrease in blood glucose, with the exception of those coated with cellobiose particles. It was discovered that pyridoxal 5-phosphate-coated particles were superior to aquasomes coated in cellobiose or trehalose for decreasing blood glucose.

Enzyme delivery by mouth: It was suggested by Rawat et al. to use a nanoscale ceramic core-based approach to ingest the acid-labile enzyme serratiopeptidase. The Nano core was created using colloid precipitation and room temperature sonication. Subsequently, the enzyme was adsorbed onto the core while being continuously stirred and covered in chitosan. The enzyme was further maintained by encasing the enzyme-loaded core in an alginate gel. TEM scans showed that the particles were spherical in form and had an average diameter of 925 nm. The enzyme loading efficiency of the particles was found to be approximately 46%.

Antigen delivery: Adjuvants that are frequently used to increase immunity to antigens have a tendency to either protect the functional groups of the antigen or change its structure through absorption. Consequently, Kossovsky et al. demonstrated the effectiveness of a particular synthetic polymer ceramic antigen transport vehicle. These nanoparticles, which were composed of an immunologically active surface molecule and a diamond substrate coated with a glassy carbohydrate (cellobiose) layer inside an aqueous dispersion, demonstrated both conformational stability and a high rate of surface exposure to protein antigens. Since diamond is an elevated material, it was originally selected for cellobiose adsorption and adhesion.

Medication delivery: Oviedo by first generating an inorganic calcium phosphate center encased in a lactose layer, Oviedo and associates were able to generate indomethacin-loaded aquasomes, which were subsequently used to adsorb the reduced medication. Aquasome strength and function, grain size, and form have all been evaluated using X-ray powder diffractometry, TEM, and SEM. It was found that the drug-loaded aquasomes had a particle size of 60–120 nanometers. TEM and SEM techniques were used to validate the spherical shape of aquasomes.

Gene delivery: It is possible to look at aquasomes for gene transfer. It shows a genetic code-loaded, aesthetically pleasing delivery system. Research indicates that aquasomes protect and maintain the structural integrity of the gene segment. A polyhydroxyl oligomeric film coating, a therapeutic gene fragment surface bound noncovalently, an additional carbohydrate film, a ceramic Nano crystalline core, and a layer of viral protein complexes designed to target stereochemical preservation are the five layers of a composition proposed for regenerative medicine. In addition to offering all of the advantages of viral vectors, the aquasome vehicle would drastically lower the likelihood of irrelevant integrated and coordinated attacks.¹⁶

ACKNOWLEDGMENT:

We are thankfull to Principal and Management of Ali Allana College of Pharmacy Akkalkuwa for providing all necessary facilities during this study.

CONCLUSION:

Aquasomes represent an innovative approach to drug delivery, distinct from traditional nanoparticles. Composed of a solid-phase nanocrystalline core enveloped by an oligomeric film, aquasomes serve as effective carriers for bioactive molecules due to their unique water-like characteristics. This characteristic facilitates the preservation of delicate biological molecules, ensuring their conformational integrity and surface exposure, thus targeting specific locations efficiently.

The principle of self-assembly underlies aquasome formation, where charged group interactions, hydrogen bonding, and structural stability play vital roles. These physicochemical processes govern the orientation of macromolecules, contributing to the formation of smart nanostructured materials or occurring naturally in biochemistry.

Aquasomes offer numerous advantages, including the maintenance of structural and biochemical consistency of drug particles, colloidal properties, and the ability to address stability issues of vulnerable drugs. By modifying aquasome surfaces, drug release can be regulated, offering controlled and targeted delivery.

Various applications have emerged for aquasomes, spanning insulin and enzyme delivery to antigen and gene delivery. For instance, aquasomes have shown promise in insulin delivery, where formulations coated with specific substances demonstrated prolonged reduction in blood glucose levels in animal models. Similarly, enzyme delivery via aquasomes has been proposed, utilizing nanoscale ceramic cores to encapsulate acid-labile enzymes for oral administration.

In antigen delivery, aquasomes have demonstrated conformational stability and high surface exposure to protein antigens, potentially enhancing immune response. Aquasomes have also been explored for medication delivery, where formulations loaded with drugs exhibited appropriate particle size and shape for effective delivery. Furthermore, gene delivery using aquasomes presents a promising avenue for regenerative medicine, offering a protective and structurally preserving environment for therapeutic gene fragments.

In conclusion, aquasomes represent a versatile and promising platform for drug delivery, characterized by their unique three-layered structure and water-like properties. Through the principle of self-assembly and targeted modifications, aquasomes offer controlled and efficient delivery of bioactive molecules, with applications across various medical fields.

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Received on 25.04.2024 Revised on 20.07.2024

Accepted on 02.09.2024 Published on 18.11.2024

Available online from December 19, 2024

Res. J. Pharma. Dosage Forms and Tech.2024; 16(4):343-349.

DOI: 10.52711/0975-4377.2024.00053