Drug Polymer Nanoparticles: An Advancement in Biomedical Solutions and Targeted Drug Delivery

Abstract

Polymer nanoparticles (PNPs) are compact particulate systems typically ranging from 10 to 1000 nm in size and have emerged as versatile platforms in modern biomedical research. Their growing importance stems from a unique combination of physicochemical properties, including tunable size, surface functionality, high drug loading capacity, and favourable biocompatibility. These features enable PNPs to act as efficient matrix carriers capable of encapsulating, protecting, and co-delivering a wide variety of therapeutic agents, including small molecules, proteins, and nucleic acids, within a single targeted delivery system. One of the key advantages of PNPs lies in their ability to improve both pharmacokinetic and pharmacodynamic profiles of drugs. By controlling drug release, enhancing solubility of poorly water soluble compounds, and reducing premature degradation or clearance, PNP-based systems can increase therapeutic efficacy while minimizing systemic toxicity. Targeting ligands can be incorporated on the nanoparticle surface to promote site-specific drug delivery, further improving treatment outcomes. A range of preparation techniques has been developed for the fabrication of advanced PNPs. These methods are generally classified according to the underlying particle formation mechanism, including polymerization-based approaches that generate nanoparticles directly and techniques that utilize preformed polymers. Advances in nanotechnology and polymer chemistry have enabled precise control over nanoparticle composition, morphology, and surface characteristics, leading to the development of sophisticated colloidal drug delivery systems. The integration of diverse nanomaterials into PNP formulations has further expanded their functional scope, significantly influencing the pharmacological and biopharmaceutical behavior of encapsulated drugs. Owing to their biocompatibility and design flexibility, PNPs have found broad applications in the treatment of cancer, neurodegenerative diseases, central nervous system disorders, and other complex medical conditions. This review elaborates on these aspects, highlighting the potential of PNPs as adaptable and powerful tools in nextgeneration therapeutic strategies.

Introduction

The class of natural or artificial materials known as polymers is made up of large molecules known as macromolecules. The size of polymer nanoparticles (PNPs) ranges from 1 to 1000 nm. Active chemicals trapped at the surface are adsorbed onto the polymeric core. Polymers possess advantageous characteristics when used as carriers in targeted medication delivery systems, making them a suitable choice of material in such systems. Polymer nanoparticles have different shapes, are easy to produce and engineer, and show interesting biomedical properties.1 These macromolecular materials dissolve, entrap, encapsulate, adsorb, or chemically attach therapeutically active ingredients.2

Polymers are light materials with several very interesting and versatile properties and can be used in a vast number of various applications. PNPS are formed variously by molding to construct diverse structures like monolayers, bilayers, thin films, and a nano-coated film that is synthesized by different methods such as film casting, spin-coating, dip-coating, and printing.3 Conducting polymers are a key element in various sectors, eg, electronics, sensors, photonics, pollution control, environment, and biotechnology.4,5 Due to their nanosize, these polymer-based nanoparticles possess superlative traits. Without changing the nature of the materials, the bulk polymer is converted into a nano-sized polymer that provides tantalizing new features. By transforming polymers into polymer nanoparticles, physicochemical property modifications will ultimately introduce the functions of nanoscience and nanotechnology.6,7

PNPs are efficient tools in terms of transportation and targeting of drugs, proteins, and genes to a specific cell that is needed. Their minute size not only allows them to remain stable during blood circulation but also facilitates their penetration through cell membranes. Polymers are essentially perfect materials to fabricate various molecular designs, which can be further combined with special properties for more efficient medicinal applications.8 Nanomedicines were created based on PNPS across various types of nanoparticles,9 hydrogel nanoparticles,10 metal-organic frameworks (MOFs),11 liposomes,12 drug nanoparticles,13–15 etc as well as different sizes and shapes. As depicted in Figure 1, the PNPs can be developed and synthesized in many different forms such as spherical polymer micelles, dendrimers, nanodiscs, nanospheres, nanoring polymersomes, and nanorods. These figures are what mainly cause the remarkable difference of their functions.

Improved drug pharmacokinetics and bioavailability, less toxicity, and the potential to increase therapeutic dosage are all benefits of PNP-based drug delivery systems converted into nanomedicines.16 PNPs’ enhanced stability and simplicity of manufacture position them as a substantial advance over conventional oral and intravenous administration techniques. With reduced toxicity and adverse drug reactions, they can be utilised in drug delivery processes, including for tissue engineering and organ distribution.

Functionalization of PNPs can occur using drugs, biomolecules, targeting agents, and other nanoparticles as shown in Figure 2. Their large surface area and small size aggregation, however, make physical handling difficult in both liquid and dry powder form. The main disadvantage is the preparation process’s usage of organic solvents, which can damage physiological systems and the environment, and ruin some pharmaceutical drug molecules.2,17,18

Polymer-based nanoparticles are a colloidal system made from natural or synthetic polymers. They retain significant advantages over other nanocarriers like micelles, liposomes, and inorganic nanosystems. The polymer has two types of nanoparticles, viz., natural and synthetic PNPs, which differ based on the preparation of nanoparticles. The natural polymer which has been produced naturally from plant origin or animal origin that dissolves in water is named natural hydrophilic polymer. For examples- starch,19 algin,20 pectin,21 xanthan gum,22 insulin, agarose etc. are natural hydrophilic polymers. The choice of polymer in polymeric nanoparticle (PNP) synthesis is a critical factor that directly influences the physicochemical properties, stability, and biological performance of the nanoparticles. Biodegradable polymers, such as poly(lactic-co-glycolic acid) (PLGA), polycaprolactone (PCL), and natural polymers like chitosan and alginate, are commonly selected due to their biocompatibility and safe degradation products. The polymer’s molecular weight, hydrophilicity or  ydrophobicity, and functional groups determine drug loading efficiency, release kinetics, and surface characteristics, which in turn affect cellular uptake and biodistribution. Additionally, polymers can be tailored or
functionalized to provide stimuli-responsiveness, targeting capabilities, or prolonged circulation times.

Therefore,polymers, such as poly(lactic-co-glycolic acid) (PLGA), polycaprolactone (PCL), and natural polymers like chitosan and alginate, are commonly selected due to their biocompatibility and safe degradation products. The polymer’s molecular weight, hydrophilicity or hydrophobicity, and functional groups determine drug loading efficiency, release kinetics, and surface characteristics, which in turn affect cellular uptake and biodistribution. Additionally, polymers can be tailored or functionalized to provide stimuli-responsiveness, targeting capabilities, or prolonged circulation times. Therefore,polymer selection is guided by the intended therapeutic application, the nature of the encapsulated drug, and the desired pharmacokinetic and pharmacodynamic profile, ensuring optimal efficacy and safety of the PNP formulation.

Synthetic polymers, including Polyacrylic acid (PAA), Polyethene glycol (PEG), Polyvinyl pyrrolidone (PVP), and Polylactic acid (PLA), are chemically synthesized and utilized in biotechnology, pharmacology, and chemistry. These polymers, extracted from regenerative sources, have been approved by the FDA as drug conjugated carriers for clinical us.23

A. Polyacrylic acid (PAA) is a homopolymer of acrylic acid which is cross-linked with allyl ether propylene. It has the potential of absorbing and retaining water and also swells many times to its original volume so it is used in disposable diapers.24

B. Polyvinyl pyrrolidone (PVP) is a binder used in tablet formation, synthesized by polymerizing vinylpyrrolidone in water or isopropanol. Its molecular weight ranges from 40,000 to 360,000, and it is widely available in different grades.25

C. Polyethene glycol (PEG) is a promising material for drug delivery due to its high drug loading ability, biocompatibility, biodegradability, extended circulation half-life, and simple functionalization.26

D. Polylactic acid (PLA) is a significant polymer suitable for synthesizing polymeric nanoparticles due to its biodegradability and biocompatibility properties. Due to its low molecular weight, PLA is chosen as a drug carrier due to its shorter degradation time, accelerating the formation of a required drug delivery system in multiple formulations.24

E. Polycaprolactone (PCL) – PCL is biodegradable polyester. PCL is formed by ring-opening polymerization of ɛ- caprolactone by using a catalyst like stannous octanoate. Variousdrugs can be encapsulated within PCL used for targeted drug delivery. PCL is conjugated with starch to obtain a good biodegradable material.27

F. Poly(lactic-co-glycolic acid) (PLGA)- PLGA, a biocompatible and biodegradable polymer, is under study as a delivery vehicle for proteins, drugs, and macromolecules like peptides, RNA, DNA, and RNA due to its tunable mechanical properties and its long-term stability.28,29 Drugs were released at specific doses without surgery, allowing active PLGA degradation. The physical properties of the polymer-drug matrix were adjusted to achieve the desired dosage and release intervals, based on factors such as polymer molecular weight, lactide-glycolide ratio, and drug concentration, depending on the type of drug.30,31

G. Polyacrylic acid (PAA) is a homopolymer of acrylic acid which is cross-linked with allyl ether propylene. It has the potential of absorbing and retaining water and also swells many times to its original volume so it is used in disposable diapers.24

H. Polyvinyl pyrrolidone (PVP) is a binder used in tablet formation, synthesized by polymerizing vinylpyrrolidone in water or isopropanol. Its molecular weight ranges from 40,000 to 360,000, and it is widely available in different grades.25

I. Polyethene glycol (PEG) is a promising material for drug delivery due to its high drug loading ability, biocompatibility, biodegradability, extended circulation half-life, and simple functionalization.26

J. Polylactic acid (PLA) is a significant polymer suitable for synthesizing polymeric nanoparticles due to its biodegradability and biocompatibility properties. Due to its low molecular weight, PLA is chosen as a drug carrier due to its shorter degradation time, accelerating the formation of a required drug delivery system in multiple formulations.24

K. Polycaprolactone (PCL) – PCL is biodegradable polyester. PCL is formed by ring-opening polymerization of ɛ- caprolactone by using a catalyst like stannous octanoate. Variousdrugs can be encapsulated within PCL used for targeted drug delivery. PCL is conjugated with starch to obtain a good biodegradable material.27

L. Poly(lactic-co-glycolic acid) (PLGA)- PLGA, a biocompatible and biodegradable polymer, is under study as a delivery vehicle for proteins, drugs, and macromolecules like peptides, RNA, DNA, and RNA due to its tunable mechanical properties and its long-term stability.28,29 Drugs were released at specific doses without surgery, allowing active PLGA degradation. The physical properties of the polymer-drug matrix were adjusted to achieve the desired dosage and release intervals, based on factors such as polymer molecular weight, lactide-glycolide ratio, and drug concentration, depending on the type of drug.30,31

Synthetic hydrophobic polymers are those which are not soluble in water or other polar solvents such as epoxides, polystyrene, polyvinylchloride (PVC), polystyrene, polyisobutylcyanoacrylates, polymethyl (methcyanoacrylates), poly (butylcyanoacrylates), and poly (alkyl cyanoacrylates).32,33

Drug therapies have long been a cornerstone of medicine, yet more than half of the currently approved medications suffer from low solubility and weak permeability, limiting their clinical utility.34 Polymer-drug conjugates, particularly those utilizing drug-loaded polymeric nanoparticles, present a highly promising therapeutic strategy. This method involves the attachment of sensitive bioactive molecules—including proteins, peptides, hormones, enzymes, and growth factors—to a hydrophilic polymer backbone through reversible, physiologically degradable linkers. These linkages protect encapsulated and potentially fragile therapeutic agents from premature enzymatic degradation and significantly prolong their circulation half-life, thereby enhancing the potential for intestinal absorption and systemic bioavailability. It is to be noted that a sustained presence in the bloodstream increases the likelihood that the conjugate will interact with its intended molecular target, establishing a controlled delivery system that enhances therapeutic efficacy while also narrowing the therapeutic window. By meticulously adjusting essential physicochemical properties such as surface charge, hydrodynamic diameter, and biocompatibility, these polymer-drug conjugates can achieve targeted and effective delivery to the specific site of action.35,36

Given their unique pharmacokinetic behavior, these entities are regarded as novel chemical entities distinct from the parent compound, and they are incorporated into standard pharmaceutical formulations by being physically entrapped within the carrier matrix.13,37 Ongoing investigation is directed at enhancing the absorption of the drug, achieving disease-targeted delivery, improving solubility, minimizing toxicity, and amplifying the therapeutic efficacy of bioactive agents by surmounting biological barriers.38–40 The employment of nanoparticles in biomedicine is underpinned by their size-dependent physical and chemical characteristics, which modify their biological behavior in ways not observed with bulk materials.41

Polymer is a macromolecule that is composed of repeating units that are organized in a chain-like structure exhibiting multiple compositions and properties. Polymeric nanoparticles (PNPs) represent a significant advancement in the field of drug delivery and are also utilized in biosensing and bioimaging applications.42 Their growing importance in targeted therapies is attributed to their ability to accumulate in specific tissues, exhibit low toxicity, and retain drugs effectively. The method of production typically corresponds to the chemical characteristics of the therapeutic compound, allowing for the use of either natural or fully synthetic polymers to achieve targeted delivery. Techniques such as surface modification and drug encapsulation enhance the therapeutic capacity of these nanoparticles while optimizing their distribution and retention in diseased tissues.43

This review highlights the potential of PNPs for the delivery of poorly soluble, hydrophobic compounds. Although such drugs often suffer from limited bioavailability, their integration with nanoparticles can markedly improve solubilization, stability, and therapeutic indices. We focus on synthetic and loading techniques that facilitate a smooth transition of these compounds from the formulation stage to clinical impact, ensuring efficient delivery to the intended site of action while minimizing off-target effects.

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Table 1 Different Synthesis Methods of PNPs

Pranita Rananaware, Mahesh Narayan & Varsha Brahmkhatri (2026) Drug Polymer Nanoparticles: An Advancement in Biomedical Solutions and Targeted Drug Delivery, Drug Design, Development and Therapy, 20:, DOI: 10.2147/DDDT.S562785

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