Nanocarrier-assisted Smart Drug Delivery Systems (SDDS) are one of the most revolutionary advances in contemporary medicine. Nanodelivery systems have been developed for improved therapeutic accuracy, higher bioavailability, and lower systemic toxicity. Different from conventional formulations, the smart nanocarriers respond to stimuli and incorporate surface engineering, molecular targeting and controlled drug release toward improved PK-PD performance. In the past 10 years, progress in material science, lipid technology, polymer chemistry and knowledge about nanobio interface have allowed the formulation of novel nanocarrier systems. These systems consist of liposomes, polymeric NPs, dendrimers, nanogels, Solid Lipid Nanoparticles (SLNs) and Nanostructured Lipid Carriers (NLCs), metallic nanoparticles, and biomimetic nanosystems as well as hybrid multifunctional constructs. These carriers can respond to both internal (pH, redox, enzymes, hypoxia and reactive oxygen species) and external (light, heat, magnetic fields, ultrasound, and electric fields) stimuli in a smart way, leading to controlled release and better therapeutic efficacy. Smart nanocarriers have shown excellent capacity for delivering cancer-targeted therapy, neurotherapy, infectious disease management, metabolic disorder management, cardiovascular diseases treatment, immunotherapy, gene therapy, and vaccination. Recent progress can be noted in the cell membrane-coated nanoparticles, lipid nanoparticle for mRNA vaccine, CRISPR/Cas9 carrier and AI-assisted design of nanocarriers, nanotheranostics and nanorobotic targeting. Despite their promising aspects, challenges remain in nanotoxicology, mass production, regulatory uniformity and evidence of long-term safety. This review provides an in-depth discussion on SDDS, including their mechanisms of action, stimulus-response mode, therapeutic applications and technological progress, for the period from 2020 to 2024, as well as safety considerations, regulatory aspects, challenges in the translation, and future directions. A structured approach incorporating PubMed, Scopus, ScienceDirect, and other electronic databases was adopted to extract the latest literature. In general, smart nanocarriers are appearing as the design elements that could revolutionize personalized medicine and targeted treatments.
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Keywords
Controlled Release
Lipid Nanoparticles
Nanocarriers
Nanomedicine
Smart Drug Delivery
Stimuli-Responsive Systems
Targeted Therapy
INTRODUCTION
Drug delivery science has undergone a technological revolution-from traditional “dumb” conventional formulations to highly engineered, nanoscale systems that potentially could be precisely controlled therapeutic tools. Conventional DDSs have many drawbacks, resulting in inefficient therapeutic efficacy with poor drug solubility, rapid blood clearance, and nonspecific tissue distribution, and inability to penetrate biological barriers, nonsustained release patterns, and systemic toxicity (Singh et al., 2022). These are severe limitations in diseases such as cancer, neurodegenerative disorders, chronic infections, autoimmune diseases, and metabolic conditions since targeted delivery and long-lasting exposure of the drug is a precondition for successful treatment.
In this context, nanotechnology has enabled the design of drug carriers at molecular and supramolecular levels to address these issues. Smart DDS, also called intelligent, stimuli-responsive, or programmable nanocarrier system, is a novel concept in the therapeutic field. While traditional nanocarriers per se were passive medicine release systems, Smart Drug Delivery Systems (SDDS) is capable of sensing biological cues and responding to the disease microenvironment for on-demand drug enrichment compared with conventional release patterns (Zhang et al., 2021).
The “smart” functions of SDDS are realized by several basic principles
Smart nanocarriers exploit these mechanisms to a great extent and lead to marked enhancement in the pharmacokinetic and pharmacodynamic properties. This comprises improvement of drug absorption, prolonged serum half-life, enhanced tissue retention and drug delivery as well as at intracellular site.
Targeted Therapy in Synchrony with Smart Nanocarriers
Several drugs which play a key role in treatment like anticancer drugs, antibiotics, peptides and proteins, and so on, experience many barriers for their drug delivery. These include:
Smart nanocarriers address these problems by
SDDS development can be divided according to technology generation into five generations:
Passive Targeting
Use of the enhanced permeability and retention effect in tumors, inflammation, and infection.
Active Targeting
Various surface ligands, for example, antibodies (HER2), peptides (RGD), transferrin, folic acid, aptamers, and carbohydrates can guide the nanocarrier to a specific receptor.
Intracellular Delivery Strategies
Programmable Release
Intelligent nanocarriers can be designed for:
Clinical Translation and Industrial Application
Some of the above smart nanocarriers have already had an important clinical application. Examples include:
These successful examples demonstrate the potential to enhance efficacy and reduce toxicity through smart delivery. This advancement brings new types of therapies, such as mRNA, siRNA, and CRISPR gene-editing constructs (Jain et al., 2023).
Justification of Reviewing Smart Nanocarriers
Although thousands of research articles have been published in this field, rapidly evolving technologies include-stimuli-responsive polymers, hybrid materials, biomimetic coatings, nanotheranostics and AI-empowered designs with gene delivery systems as the next generation. Therefore, an earlier review and thorough understanding is of vital necessity to: list up-to-date developments (2020-4); describe technological principles; illustrate targeting and stimuli-responsive systems.
Focus on clinical applications and regulatory challenges show prospects of precision medicine in the future offer guidance to researchers, developers, and patients. The purpose of this review is to provide a one-stop reference source that highlights recent developments, modes of action, therapeutic implications, hurdles, and projected advances in the smart nanocarrier-based drug delivery systems (Santos and Araujo, 2021).
METHODOLOGY
The methodological strategy used in this narrative literature review was rigorously planned to achieve systematic rigor, scientific validity, and up-to-date information on the subject of smart nanocarrier-triggered drug delivery systems.
As a review article, not original research, this study was conducted using a systematic and reproducible approach to improve its transparency and trustworthiness.
Literature Search Strategy
We conducted an electronic search in several scientific databases including the following:
A search was conducted for articles published between 2010 and 2024 with particular emphasis on recent advances (from 2018 to 2024), that is, a period characterizing fast growth and very intensive improvement in stimuli-responsive nanocarriers and advanced smart material engineering.
Keywords and Search Terms
To cover all potential resources, we used a combination of MeSH terms and Boolean operators.
Combinations of keywords such as (smart nanocarriers) AND (targeted therapy), and also (stimuli-responsive nanoparticles) AND (drug release), were used to retrieve highly relevant and impactful studies.
Inclusion Criteria
Inclusion criteria were as follows for the articles:
The Process of Selection
A methodical three-phase screening approach was employed:
In the first search, approximately 2000 records were identified and 214 full-text articles were screened. These included original-research articles, clinical studies, systematic reviews, and high-quality experimental data.
Data Extraction and Synthesis
Extracted data included:
Overview of SDDS
SDDS represents a major advancement in pharmaceutical nanotechnology, providing programmable, site-specific, and stimuli-responsive delivery of therapeutic agents. In contrast to traditional drug-delivery system, which rely on passive diffusion and exhibit nonselective tissue distribution, SDDS should have an active interface with biological microenvironment, retaining the drug until it meets particular internal or external triggers. Thus, the intelligent responses of SDDS enable maximized therapeutic effectiveness while minimizing systemic toxicity incurred in addition to overcoming multiple physiological barriers which natural drugs are powerless against.
Origin and Evolution of Smart DDS
The concept of smart drug delivery was pioneered to overcome certain limitations of conventional nanocarriers, such as uncontrolled release, rapid systemic clearance, and inability to respond to physiological signals. To overcome these limitations, early researchers began integrating responsive polymers, biochemical sensors, and functional ligands into these systems, enabling them to:
Mechanism of Action of Smart Nanocarriers
Smart drug-delivery systems function through several integrated mechanisms:
Stimuli-Responsive Behavior
SDDSs are designed to respond to either endogenous (internal) or exogenous (external) stimuli.
Common internal triggers include:
External triggers include:
These nanocarriers, being smart, change conformation or chemistry upon sensing these triggers, leading to controlled drug release.
Mechanisms for Targeted Delivery
Targeting increases specificity and also enhances the accumulation of nanoparticles in diseased sites.
Smart nanocarriers use:
Controlled or Programmable Release
For example, smart nanocarriers can be designed to:
Classification of Smart Drug Delivery Systems
Material Composition
Responsiveness
Therapeutic Uses
This classification highlights the flexibility and adjustability of SDDS for different therapeutic requirements.
Benefits of Smart Drug Delivery Systems
The above smart nanocarriers have the following advantages in terms of conventional systems:
These are among the properties that render smart nanocarriers most suitable for precision medicine (Mohan et al., 2024).
Limitations and Hurdles for Smart Nanocarriers
Despite significant achievements, a number of obstacles are still encountered by the SDDS:
Addressing these challenges would be critical for broader clinical translations (Bera et al., 2021).
Clinical Consideration and New Developments
Smart nanocarriers are increasingly entering clinical investigation with success seen in:
Nanocarriers of siRNA and gene editing, Patisiran-the first FDA-approved siRNA therapy (Patel et al., 2021).
Types of Smart Nanocarriers
Advanced drug delivery technologies, such as smart nanocarriers, such as smart nanocarriers, represent a significant advancement in modern medicine, as their site-specificity and on-demand precision enable targeted therapeutic control. In contrast to the mainstream delivery vehicle for drugs, including core products in a nonspecified way in the body, smart nanocarriers can be designed to identify some specific biological signs and make a response, then unload the drug only at the target region. This approach enhances the therapeutic efficacy, reduces toxicity and improves patient compliance. The developed smart nanocarriers so far are with diversified properties and functions.
Polymeric Nanoparticles
Polymeric nanoparticles are the most investigated among the nanocarrier systems, because of their good biocompatibility, biodegradability and inbuilt drug-loading capacities. Nanoparticles are commonly developed using natural polymers, including chitosan and alginate, as well as synthetic polymers like PLGA, PEG and PCL. Polymeric nanoparticles offer protection from early drug degradation by encapsulating both hydrophilic and lipophilic drugs.
Recent developments include polymeric systems that respond to Ph, enzymes, or temperature stimuli, enabling active, site-specific drug delivery. Such systems are promising for treating difficult conditions like cancer and chronic inflammation (Dutta et al., 2024).
Liposomes
Liposomes are spherical vesicles composed of phospholipid bilayers and may entrap various therapeutic agents such as small drugs, proteins and nucleic acids. They exhibit low drug toxicity and increased circulation time when pegylated.
More advanced smart liposomes are thermosensitive liposomes, which release the drugs upon mild heating, pH-responsive liposomes that target the tumor and ligand-coupled (ligand-incorporated) liposome, that is receptor-mediated. Clinical application potential of such systems is demonstrated by FDA-approved liposomal formulations (i.e., liposomal doxorubicin).
Solid Lipid Nanoparticles and Nanostructured Lipid Carriers
SLNs and NLCs are second generation lipid-based nanocarriers that have the benefit of both polymeric nanoparticles and conventional lipid systems. SLNs enhance the stability, sustained release, and drugs protection against chemical degradation. Although SLNs have relatively slower drug-loading, second-generation NLCs compensate by incorporating both solid and liquid lipids. Due to their great biocompatibility and capability of improving the bioavailability of highly hydrophobic, poorly water-soluble drugs, these carriers are widely used in transdermal, oral, or ocular delivery systems.
Dendrimers
Dendrimers are a class of highly branched macromolecules, which have very reactive surface functional groups and are in the size range of nm. Owing to their three-dimensional tree-like morphology, dendrimers’ size, shape, and surface chemistry can be easily tailored. Therefore, dendrimers are able to accommodate numerous drug molecules, imaging agents and targeting ligands simultaneously and are thus ideal for multifunctional theragnostic purposes. The surface modification with PEG, antibodies or peptides improves targeting and reduces toxicity. PAMAM dendrimers are one of the most widely studied classes of dendrimer systems (Banerjee and Gohil, 2021).
Carbon-Based Nanocarriers
Of these carbon nanomaterials, CNTs, GO, and fullerenes have become promising candidates mainly attributed to their very high mechanical strength, large surface area as well as superior penetrating ability into cellular membranes. In the case of functionalized CNTs and GO, high-efficiency drug delivery for anticancer drugs as well as nucleic acid and peptides are possible, but long-term biocompatibility and toxicity concerns remain and encourage further studies regarding safe surface modifications (Wang et al., 2024).
Metallic and Inorganic Nanocarriers
Metal nanoparticles, like gold, silver, and iron oxide and inorganic systems such as silica or calcium phosphate have some unique characteristics that give them an advantage over others: magnetic responsiveness and photothermal activity as well as high drug-loading capacity. Gold and iron oxide nanoparticles can deliver targeted phototherapies and magnetically guided to specific tissues. Mesoporous silica nanoparticles are among the most extensively studied systems because of their controllable pore structure and drug promising multidrug-carrying capacity.
Exosomes and Biomimetic Nanocarriers
Exosomes are cell-derived endogenous nanovesicles, which play an essential role in intercellular communication. Biomimetic nanocarriers such as cell membrane-coated nanoparticles, combine synthetic systems with biological camouflage to enhance circulation time and evade the immune system.
Targeting Mechanisms and Stimuli Responsiveness
Intelligent nanocarrier-mediated drug delivery systems are designed to interact with the biological environment, aiming at transporting therapeutic molecules where they are required and when needed. Their targeting capacity, which is based on passive and active targeting mechanisms, as well as on the response to specific internal or external stimuli. These mechanisms serve not only to enhance drug accumulation at the disease site but also decrease systemic exposure, thus increasing efficacy and reducing side effects.
Passive Targeting
Passive targeting is based on the inherent physiological properties of the body, which allow nanocarriers to accumulate in diseased tissues (e.g., tumors and inflammatory sites). This is primarily enabled by the EPR effect, in which tumor-associated vasculature and their lymphatic drainage accumulate nanocarriers hundreds of nm in size, moved. Induced vascular permeability, as occurs in inflammatory diseases, also enables passive accumulation. Passive targeting is particularly attractive for use in cancer therapy, as it avoids the need to make specific surface modifications or conjugations for targeting, and instead utilizes particle size, shape, and circulation time to improve biodistribution.
Active Targeting
Active targeting: This approach is the attachment of some specific ligands on the nanocarrier surface, and is used for selective binding with overexpressed receptors in target cells. Ligands may include antibodies, peptides, aptamers, folic acid, transferrin and the like. When the ligand is bound to the target receptor, receptor-mediated endocytosis occurs in relation to nanocarrier and can markedly promote the intracellular drug delivery. Active targeting introduces more specificity and decreases nonspecific toxicity. It is not only for anticancer drugs but also for antiviral molecules. For example, folate-targeted nanomaterials are extensively used because the folate receptor is overexpressed in various cancers.
Stimuli-Responsive Targeting
Stimuli-responsive nanocarriers release their therapeutic payload in the presence of certain internal or external triggering factors. Such smart systems ensure that drugs are not released prematurely but are activated only at their target sites.
Internal stimuli
Internal stimuli are the physiological parameters that differ between normal and diseased tissues. The pH-sensitive systems are designed for drug liberation in the acidic environment, such as that of the tumor microenvironment or endosomes and lysosomes. These enzyme-responsive nanocarriers would break up and release drugs in response to the presence of disease-associated enzymes, such as MMPs or esterase enzymes. Multiple redox-responsive mechanisms activate in response to the high levels of GSH inside cancer cells and thereby can result in selective intracellular drug release. Internal stimuli-centered targeting works very well in cancer, inflammation, and ischemic diseases.
External stimuli
The drug release can be triggered by various external stimuli very efficiently and specifically in space and time:
These systems, triggered externally, are of great value in targeted cancer therapy and localized drug delivery.
Cellular Uptake Mechanisms
Once nanocarriers arrive at the target site, they must be internalized efficiently by cells. Smart nanocarriers use various internalization mechanisms to improve intracellular drug accumulation:
Surface charge, particle size, and hydrophobicity show remarkable effects on cellular endocytosis. Nanocarriers can also be tailored to escape the endosome by exhibiting proton sponge effects or pH-buffering functionality, allowing drug delivery into the cytoplasm or nucleus.
Controlled and Sustained Drug Release
The beneficial effect of using smart nanocarriers is the controlled drug release, which can avoid peak‐trough variations and enhance therapeutic efficacy. The various controlled-release systems available are:
Overcoming Biological Barriers
In particular, smart nanocarriers configurations will drive the breakthrough in several biological bottlenecks associated with current drug delivery approaches:
Emerging strategies such as cell membrane-coated nanomaterials and exosome-like carriers or surface-modified nanocarriers further aid in immune evasion by prolonging circulation time (Singh et al., 2023).
Smart Nanocarrier Applications
Smart nanocarriers have fundamentally altered the field of therapeutics by offering tailored, site-specific, and regulated drug delivery for a range of clinical conditions. They are versatile platforms due to their tunable physicochemical properties, capability to overcome biological barriers, and responsiveness to both internal and external stimuli. This section describes the major therapeutic applications of smart nanocarrier-based drug delivery systems.
Cancer Therapy
Tumors are ideal candidates for both passive and active targeting strategies due to their leaky vasculature, hypoxic conditions, and disrupted metabolic pathways (Li et al., 2023).
Contagious Illnesses
The efficacy of antimicrobial, antiviral, and antiparasitic drugs, especially in infections requiring targeted delivery, is improved through the use of nanocarrier-based delivery systems (Singh et al., 2024).
Neurological Disorders
Smart nanocarriers offer strategies to enhance the transport of drugs across blood brain barrier.
BBB penetration and targeting
To overcome the blood-brain barrier, intelligent nanocarriers employ cell-penetrating peptides and receptor-mediated transport via transferrin and insulin receptors.
Regenerative and neuroprotective treatments
Neurotrophins, antioxidants, anti-inflammatory drugs, or genetic materials can be delivered by nanocarriers to promote neuronal survival and repair.
Cardiovascular Diseases
Smart nanocarriers potentially provide a novel strategy for the treatment of cardiovascular diseases by transporting drugs to damaged or inflamed vessels. These systems enable targeted drug delivery to atherosclerotic plaques. Nanocarriers can be tailored to target overexpressed molecules in atherosclerosis, such as VCAM-1, ICAM-1 or scavenger receptors (Li et al., 2024).
Diabetes and Metabolic Disorders
Intelligent nanocarriers offer novel approaches to enhance the delivery of insulin, peptides, and oral antidiabetic drugs (Khan et al., 2022).
Oral insulin and peptides
Nanocarriers protect insulin from enzymatic degradation in the gastrointestinal tract and enhance lymphatic or mucosal absorption.
Controlled and sustained release
Polymeric and lipidic nanovehicles provide sustained drug release, enhancing glycemic control and improving patient compliance.
6.6 gene delivery/gene therapy
Nanocarriers are vehicles for delivery of therapeutic nucleic acids, including siRNA, mRNA, plasmids and CRISPR components.
Protection and targeted delivery
Smart nanocarriers protect genetic materials from nuclease digestion, enhance cellular uptake and facilitate targeted intracellular release, resulting in efficient gene silencing or editing.
Applications in precision medicine
Gene-editing nanocarriers are being tested for treating inherited disorders, cancers, and viral infections.
Immunotherapy and Vaccine Delivery
Intelligent nanocarriers can significantly augment vaccine efficacy by promoting antigen targeting to immune cells.
Targeting dendritic cells
Functionalized nanocarriers deliver antigens to dendritic cells, enhancing immunity and vaccine effectiveness.
Nucleic acid vaccines and adjuvants
Lipid nanoparticles, including those used for the mRNA vaccine such as COVID-19 vaccine, are among the best examples of how smart nanocarriers have revolutionized global vaccination strategies.
Regenerative Medicine
Nanocarriers also promote tissue regeneration by maintaining growth factors, stem cell modulatory molecules, and biomolecules on damaged tissues.
Pulmonary and Inhalation Delivery
Smart nanoparticles could be inhaled for the treatment of respiratory diseases (asthma, COPD, pulmonary tuberculosis and lung cancer).
Ophthalmologic and Dermatologic Uses
Nanocarriers facilitate drug penetration across ocular and skin barriers, thus enhancing their therapeutic effect.
Recent Advancements (2020-4)
During the of 2020-4, research on smart nanocarriers has observed tremendous growth. This is attributed to the continuous advancements in the fields of nanofabrication, materials science, artificial intelligence, and other elements of precision medicine. Such advancements have transformed the potential of nanocarriers in disease diagnosis, monitoring, and treatment with unparalleled accuracy, safety, and efficacy.
The following are other key advancements that define the contemporary smart nanocarrier technology.
AI-Powered Nanocarrier Design and Optimization
Key advancement:
Biomimetic and Cell-Membrane-Coated Nanocarriers
Research on biomimetic nanocarriers has grown tremendously since 2020, focused on the immune evasion characteristics.
2020-4 road map:
Multifunctional (Theranostic) Nanocarriers
Theranostic, or the seamless integration of therapy with diagnostics, is one of the most rapidly advancing technology areas.
Innovations:
CRISPR, mRNA, and Gene-Editing Nanocarriers
Research on genetic nanomedicines has increased significantly due to the success of mRNA vaccines in the COVID-19 pandemic.
2020-4 highlights:
Stimuli-responsive technology has significantly matured
Major improvements:
Advances in Nanocarrier Penetration Across Biological Barriers
Research from 2020 to 2024 has focused on overcoming challenging physiological barriers.
Key breakthroughs:
Smart Hydrogels, Nanogels, and Injectable Nanomaterials
Research of hybrid systems and nanogels expanded considerably following 2020.
Recent advancements:
Hydrogels and their nanoscale advantages were synergistically integrated into these systems.
Microfluidic and 3D Printed Nanocarriers
Recent improvements in microfabrication technology have increased the accuracy and repeatability in the production of nanocarriers.
2020-4 advancements:
These systems respond to prior challenges with manufacturing and scaling.
Targeted Nanoimmunotherapy
The use of nanotechnology for immunotherapy to boost immune response has grown considerably.
Recent progress:
Green and Biodegradable Nanocarriers
Recent advancement:
Difficulties and Limitations
Despite the impressive progress in smart nanocarrier-based drug delivery systems with promising therapeutic potential, still exist many barriers and limitations for their broad clinical translation due to toxicity, stability, cost, regulations, scalability, and unexpected biological interactions. The development of safe, efficacious, and clinically translatable nanocarrier systems should be based on knowledge of these challenges.
Safety and Nanotoxicity Concerns
Unanticipated toxicological effects may result from interactions of nanocarriers with cells at the cellular and subcellular levels.
Organ toxicity and cytotoxicity
Some nanomaterials induce inflammation, oxidative stress, mitochondrial injury or membrane disturbance. Examples include metal nanoparticles (e.g., Au, Ag, Fe-oxide NPs) causing the death via ROS generation.
Immunogenicity
Surface charge, size and composition influence the nature of immune responses. Nanoparticle carriers (e.g., pegylated ones) can induce hypersensitivity responses or complement system activation.
Accumulation during prolonged treatments
Nondegradable nanoparticles may accumulate over time in the organs (liver, spleen, kidneys and lungs) which would be hazardous.
Physiological and Biological Barriers
Many in vivo challenges are associated with the distribution, stability, and therapeutic potential of intelligent nanocarriers.
RES clearance
The RES clears foreign particles rapidly by the liver and spleen’s macrophages. Nanoparticles could not effectively target the tissues without the right surface modification, that is, PEGylation or bio-inspired coating.
Protein corona formation
Immediately upon entering the circulation, proteins attach to nanoparticle surfaces, which leads to the formation of a protein corona, modifying targeting specificity, biodistribution, therapeutic activity, and immunogenicity. This renders in vivo behavior unpredictable.
Heterogeneous tumor microenvironment
Nanoparticle penetration and distribution within tumors are thus limited by variable vascular permeability, high interstitial pressure, and hypoxic regions.
Stability and Drug Loading Associated Challenges
Nanocarriers need to maintain structural integrity in fabrication, storage, and physiological circulation.
Early drug leakage
The drug’s therapeutic efficacy may be diminished if it is released before it reaches the target site due to poor encapsulation or unstable polymer/lipid matrices.
Poor drug loading efficiency
Poor loading of either hydrophobic or hydrophilic drugs limits the clinical utility of some nanocarrier systems.
Aggregation and degradation
Variations in pH, ionic strength, and temperature of the medium can distort the nanoaggregates.
Manufacturing and Scalability
A challenge remains in the industrially scaled production of smart nanocarriers while maintaining their quality and reproducibility.
Complex manufacturing processes
Smart nanocarriers require the following sophisticated fabrication techniques:
High production costs
Purification, characterization, and formulation significantly increase production costs, making commercialization very difficult.
Reproducibility limitations
Minor variations in the manufacturing processes can cause substantial differences in the size, charge and behavior of nanoparticles.
Ethical and Regulatory Challenges
Regulation of the field of nanomedicine is in flux.36373839
Lack of regulatory guidelines
There is a lack of standardized guidelines for nanoparticles since they are more complex than drugs or devices, which makes it difficult to fit them within the existing regulatory system.
Long-term lack of safety information
Comprehensive long-term toxicity and ecologic effect studies, necessary for regulatory purposes, are time-consuming and expensive.
Ethical issues
Nano waste, patient consent, and the use of advanced technology raise ethical issues.
Obstacles to Clinical Translation
Few nanocarriers make it to clinical use, despite the fact that many exhibit outstanding preclinical outcomes.
Distinctions between humans and animal models
Human outcomes are difficult to predict because immune responses and nanoparticle distribution differ significantly between species.
Restricted clinical research
The quantity of nanocarriers entering clinical trials is decreased by high development costs and intricate design specifications.
Human studies failure
Lack of Efficacy, unpredicted toxicity or poor patient acceptability may cause some nanocarriers to fail in human studies.
Environmental and Disposal Concerns
Production of synthetic nanoparticles and their large-scale use can be environmentally toxic (World Health Organization, 2022).
Difficulties with Biodistribution and Targeting
The distribution of nanoparticles may be restricted by fibrotic or calcified tissues, which would lessen the therapeutic benefit.
Future Perspectives
The future lies in the following advancements:
CONCLUSION
Smart nanocarrier-based drug delivery systems are revolutionizing modern therapeutics by offering precision, controlled release, and targeted drug action. Integration of nanotechnology with biotechnology, materials science, and artificial intelligence continues to expand its potential. While challenges remain in biosafety and regulatory translation, SDDS holds promise for becoming a cornerstone of personalized, safe, and effective therapy.
Acknowledgments
The authors express their sincere gratitude to Aditya Bangalore Institute of Pharmacy Education & Research (ABIPER), Bengaluru, Karnataka, India, for providing academic support and access to scientific resources during the preparation of this manuscript. The authors also thank the faculty members and colleagues who contributed valuable insights during the development of this review.
Author Contributions
Navitha GA: Conceptualization, literature review, data extraction, manuscript drafting, referencing, and final editing.
Likitha K. literature review, data compilation, critical revision of manuscript sections, and proofreading.
All authors have read and approved the final version of the manuscript.
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Conflict of Interest
The authors declare that there is no conflict of interest.
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