INTRODUCTION:

Polymeric nanoparticles (NPs) have sparked a lot of attention in recent years owing to its unique features that come from their small size^1-2. Polymeric NPs as drug carriers have several features, including the capacity to control drug release, shield drug and other biologically active compounds from the environment, and improve bioavailability and therapeutic index^3-4. The term "nanoparticle" refers to both nanocapsules and nanospheres, which are morphologically distinct^5-6. Nanocapsules have an oily core in which the medicine is normally dissolved, and a polymeric shell that regulates the drug's release profile from the core⁷. The medication can be maintained inside or adsorbed onto the surface of nanospheres, which are made up of a continuous polymeric network^8-9. The reservoir framework (nanocapsule) and matrix system (Nanosphere) are two different forms of polymeric NPs^10-11. Among the most intriguing techniques to obtaining local controlled therapeutic delivery is the use of polymeric nanoparticles.

Polymeric nanoparticles are colloidal solid particles with a diameter ranging of 10 to 1000nm that can be spherical, branched, or shell structures built from biodegradable and non-biodegradable polymers, wherein substances are embedded into nanoparticles through dissolution, entrapment, adsorption, and attachment, or encapsulation¹². In order to ensure effectiveness, polymeric nanoparticles are a major advance over traditional oral and intravenous methods. Polymeric nanoparticles could be efficiently utilized in numerous drug delivery operations, such as tissue engineering, as well as therapeutic delivery for non-human animals¹³. Polymeric nanoparticles are attractive candidates for treating cancer, vaccine administration, contraception, and delivery of targeted antibiotics due to their choice of polymer and capacity to adjust drug release via polymeric nanoparticles^14-15.

Advantages of Polymeric Nanoparticle:¹⁷

· Controlled and sustained release of active during transit and at the point of administration, modifying the drug's organ distribution and subsequent clearance in order to improve therapeutic potential and reduce side effects.

· Lower toxicity and the occurrence of adverse medication responses, as well as improved drug consumption.

· Targeting ligands could be attached to the surface of the particles or magnetic guiding is used to accomplish site deliberate targeting.

· The system can be used in a diversity of treatment modalities, such as oral, nasal, parenteral, intra ocular, and so on.

Fig 1: Diagram of Polymeric Nanoparticle¹⁶

Different Approaches for Synthesis of Polymeric Nanoparticle:

The technological advancement of emulsification equipment has prompted the development of the solvent evaporation technique, which has prompted the development of methods for emulsion preparation with nanoscale droplets over the last decade. Although this procedure is simple and adaptable, it can only be used with liposoluble medicines, it is time consuming, and nanoparticle coalescence during evaporation is a possibility¹⁸.

Emulsification-solvent diffusion:

It involves creating a traditional o/w emulsion from a somewhat water-miscible solvent containing the polymer and medication and an aqueous solution containing a surfactant. To establish the initial thermodynamic equilibrium of both liquids, the polymer solvent and water must be mutually saturated at room temperature for this approach to work. The development of colloidal particles is induced by solvent diffusion from the dispersed droplets into the exterior phase after dilution with a large volume of water ^19-20. Diffusion rather than direct evaporation of the organic solvent from the nanodroplets is a more gentle procedure. Unlike approaches based on solvent evaporation, the droplet size in this technique falls abruptly over a millisecond time scale during solvent diffusion^21-22. This process is usually used to make nanospheres, but it may also be used to make nanocapsules by simply adding a small amount of oil. Finally, evaporation or filtering can be used to remove the solvent, relying on its boiling point.

Fig 2: Diagram of Emulsification-solvent diffusion²³.

Emulsification–reverse salting-out:

The recently reported emulsification solvent diffusion approach can be thought of as a refinement of the emulsification-reverse salting-out method^24-25. The key distinction is in the emulsion's composition, which is made up of a water-miscible polymer carrier such as acetone and an aqueous gel comprising the salting-out agent and a colloidal stabilizer. Electrolytes like magnesium chloride, calcium chloride, or magnesium acetate, as well as non-electrolytes like sucrose, are good salting-out agents. The emulsification is accomplished using the Ouzo effect rather than high-shear forces ^26-27. By saturating the aqueous phase, the miscibility of acetone and water is lowered, allowing the production of an o/w emulsion from the otherwise miscible phases. Dilution of the produced o/w emulsion including an excess of water promotes the diffusion of acetone into the aqueous medium, resulting in the precipitation of the polymer dissolved in the emulsified nanodroplets, resulting in a reverse salting-out action. Cross-flow filtration removes the leftover polymer solvent and salting-out agent^28-29. Adequate miscibility of the organic solvent and water is not required, although it facilitates the execution process. If this is not the case, a higher water/solvent volume proportion will be required throughout nanoparticle production.

Fig 3: Diagram of Emulsification–reverse salting-out ²³.

Nanoprecipitation method:

This technique's core premise is based on the interfacial deposition of a polymer when the organic solvent is displaced from a lipophilic solution to the aqueous environment. The polymer is dissolved in an intermediate polarity water-miscible solvent and then introduced to a stirred aqueous phase in a single shot, sequentially, dropwise, or by controlled addition rate³⁰. Nanoparticles form instantly in an order to dodge water molecules due to the fast spontaneous diffusion of the polymer solution into the aqueous phase. The Marangoni effect appears to govern this phenomenon, in which a decrease in the interfacial conflict between two phases increases the surface area due to fast diffusion, resulting in the creation of tiny droplets of organic solvent³¹. The polymer precipitates in the form of nanocapsules or nanospheres as the solvent diffuses out of the nanodroplets. The organic phase is typically introduced to the aqueous phase; however the procedure might be reversed without impacting nanoparticle production. Acetone is the most commonly used organic solvent since it is miscible with water and quick to evaporate. Nonetheless, ethanol and binary solvent mixes, such as acetone with a tiny amount of water, ethanol, or methanol, can be utilised ³². As long as the solubility, insolubility, and miscibility requirements are met, either two organic or two aqueous phases can be used. Surfactants are often used in the technique to enhance the integrity of the colloidal suspension, but their existence is not needed for nanoparticle creation. The resultant nanoparticles are typically well-defined in size and have a limited size variation, which is superior to that, obtained using the emulsification solvent evaporation technique ³³.

Fig 4: Diagram of Nanoprecipitation Method ²³.

Dialysis:

The dialysis approach has been used to make small PNPs with a restricted size distribution successfully ³⁴. It's regulated by a method similar to that of the nanoprecipitation technique, but with a bit distinct test design. As a physical barrier for the polymer, dialysis tubes or semipermeable membranes with a sufficient molecular MWCO are employed³⁵. The polymer is usually emulsified, inserted into the dialysis membrane, and dialyzed against a non-solvent. The inclusion of dilute polymer solutions and the miscibility of the solvents are also essential requirements. As the solvent within the membrane is displaced, the mixture becomes less capable of dissolving the polymer. Furthermore, a rise in interfacial tension causes. Furthermore, an elevation in interfacial tension causes polymer agglomeration and the creation of a colloidal nanoparticle suspension. Whereas dialysis is a straightforward and frequent approach, the enormous volume of counter dialyzing liquid could cause the nanoparticle payload to be released prematurely due to the lengthy process.

Fig 5: Diagram of Dialysis method²³.

CONCLUSION:

Nanomedicine holds the prospect of developing novel therapeutic platforms that are more effective and have fewer negative effects than traditional formulations. The advantage of delivery systems with nanoscale dimensions is that they have the highest volumeto-size ratio of any dose form. Nanoplatforms have been used in the field of oral medication administration to improve drug solubility, absorption, and bioavailability due to this feature. Nanoformulations also offer the potential to safeguard labile APIs and control drug release, as well as to treat chronic GI illnesses by site-specific and target-oriented delivery.In particular, the development of nanocarriers for oral drug administration has covered three primary sectors of application, in our opinion: increasing the bioavailability of APIs in BCS classes II and IV, treating specific GI regions locally, and delivering biotherapeutics (protein, peptide, and nucleic acids).

To summarise, nanomaterials research for oral medication delivery has recently seen a diversification of material kinds and a rise in the complexity of formulations, as well as the development of new "smart" nanosystems.

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Received on 12.05.2022 Modified on 08.06.2022

Asian J. Res. Pharm. Sci. 2022; 12(4):341-344.

DOI: 10.52711/2231-5659.2022.00058