Nano lipid-drug conjugate: An integrated review

On the formation and stability mechanisms of diverse lipid-based nanostructures for drug delivery

In the evolving landscape of nanotechnology and pharmaceuticals, lipid nanostructures have emerged as pivotal areas of research due to their unique ability to mimic biological membranes and encapsulate active molecules. These nanostructures offer promising avenues for drug delivery, vaccine development, and diagnostic applications. This comprehensive review explores the complex mechanisms underlying the formation and stability of various lipid nanostructures, including lipid liquid crystalline nanoparticles and solid lipid nanoparticles. Drawing upon a wide array of studies, we integrate current knowledge on the physicochemical properties of lipids that contribute to nanostructure formation, such as lipid composition, charge, and the role of environmental factors such as pH and ionic strength. We further discuss the stabilisation mechanisms that preserve the integrity and functionality of these nanostructures in biological systems, highlighting the influence of surface modification, PEGylation, and the incorporation of stabilising agents. Through a methodical examination of both classical theories and cutting-edge research, our review highlights the critical factors that dictate the self-assembly of lipids into nanostructures, the dynamics of their formation, and the interplay between different stabilising forces. The implications of these insights for the design of lipid-based delivery systems are vast, offering the potential to enhance the bioavailability of therapeutics, target specific tissues or cells, and minimise adverse effects. The integration of lipid nanostructures in pharmaceutical nanotechnology not only stands to revolutionise the delivery of therapeutic agents but also paves the way for innovative applications in targeted therapy, personalised medicine, and vaccine adjuvant development. By bridging the gap between fundamental biophysical studies and applied research, this review contributes to the ongoing discourse on lipid nanostructures, advocating for a multidisciplinary approach to harness their full potential.

A Review: Surface Engineering of Lipid-Based Drug Delivery Systems

This review explores the evolution of lipid-based nanoparticles (LBNPs) for drug delivery (DD). Herein, LBNPs are classified into liposomes and cell membrane-based nanoparticles (CMNPs), each with unique advantages and challenges. Conventional LBNPs possess drawbacks such as poor targeting, quick clearance, and limited biocompatibility. One of the possible alternatives to overcome these challenges is surface modification of nanoparticles (NPs) with materials such as polyethylene glycol (PEG), aptamers, antibody fragments, peptides, CD44, hyaluronic acid, folic acid, palmitic acid, and lactoferrin. Thus, the main focus of this review will be on the different surface modifications that enable LBNPs to have beneficial properties for DD, such as enhancing mass transport properties, immune evasion, improved stability, and targeting. Moreover, various CMNPs are explored used for DD derived from cells such as red blood cells (RBCs), platelets, leukocytes, cancer cells, and stem cells, highlighting their unique natural properties (e.g., biocompatibility and ability to evade the immune system). This discussion extends to the biomimicking of hybrid NPs accomplished through the surface coating of synthetic (mainly polymeric) NPs with different cell membranes. This review aims to provide a comprehensive resource for researchers on recent advances in the field of surface modification of LBNPs and CMNPs. Overall, this review provides valuable insights into the dynamic field of lipid-based DD systems.

Novel inhalation therapy in pulmonary fibrosis: principles, applications and prospects

Pulmonary fibrosis (PF) threatens millions of people worldwide with its irreversible progression. Although the underlying pathogenesis of PF is not fully understood, there is evidence to suggest that the disease can be blocked at various stages. Inhalation therapy has been applied for lung diseases such as asthma and chronic obstructive pulmonary disease, and its application for treating PF is currently under consideration. New techniques in inhalation therapy, such as the application of microparticles and nanoparticles, traditional Chinese medicine monomers, gene therapy, inhibitors, or agonists of signaling pathways, extracellular vesicle interventions, and other specific drugs, are effective in treating PF. However, the safety and effectiveness of these therapeutic techniques are influenced by the properties of inhaled particles, biological and pathological barriers, and the type of inhalation device used. This review provides a comprehensive overview of the pharmacological, pharmaceutical, technical, preclinical, and clinical experimental aspects of novel inhalation therapy for treating PF and focus on therapeutic methods that significantly improve existing technologies or expand the range of drugs that can be administered via inhalation. Although inhalation therapy for PF has some limitations, the advantages are significant, and further research and innovation about new inhalation techniques and drugs are encouraged.

Apolipoprotein E3 functionalized lipid-drug conjugated nanoparticles of Levetiracetam for enhanced delivery to the brain: In-vitro cell line studies and in-vivo study

A significant portion of brain-tumor patients suffer from 'brain-tumor-related epilepsy (BTE)' which results in depression, anxiety and hampered quality of life. Conventional anti-epileptic drugs indicate negative interaction with other drugs augmenting the poor outcome of overall therapy. Levetiracetam (LVM) has evidenced effectiveness for BTE but its hydrophilicity restricts the passage into blood-brain barrier. The majority of lipid nanoparticles fails to load hydrophilic drug sufficiently. Therefore, lipid-drug conjugates (LDC) were synthesized using stearic acid via amide bond formation confirmed by FTIR and NMR. The nanoparticles of synthesized LDC were prepared by solvent injection method followed by functionalization with Apolipoprotein E3 (ApoE3@LDC-NP). The nanoparticles were characterized by DSC, XRD, particle size (131.6 ± 1.24 nm), zeta potential (-15.6 ± 0.09 mV), and for storage stability. In-vitro release study indicated initial burst release of 20 ± 0.63 % followed by sustained release up to 30 h (66 ± 1.40 %) for ApoE3@LDC-NP. The cell-line study on HEK293 indicated no significant cytotoxic effect and greater cell uptake through U87MG cell line. The pharmacokinetic and bio-distribution study indicated 2.5-fold greater brain-targeting of ApoE3@LDC-NP as compared to LVM solution. It proved safe in the haemolysis study and exhibited the absence of tissue necrosis. Thus, ApoE3@LDC-NP might be a promising approach for effective brain-targeting of LVM for improved clinical response in BTE.

Potential lipid-based strategies of amphotericin B designed for oral administration in clinical application

Amphotericin B (AmB) is regarded as a first-line therapy against life-threatening invasive fungal infections. Due to its poor oral bioavailability, AmB is restricted to intravenous administration in clinical practice. As science continues to move forward, two lipid-based formulations are successfully developed for oral AmB administration, currently undergoing phase I clinical trials. Encouragingly, lipid-AmB conjugates with emulsions also exhibit a better bioavailability, which may be another strategy to design oral AmB formulation in clinical practice. Thus, this review mainly focused on the two lipid-based formulations in clinical trials, and discussed the potential perspectives of AmB-lipid conjugation-loaded nanocochleates and emulsions.

Selective Protein of Interest Degradation through the Split-and-Mix Liposome Proteolysis Targeting Chimera Approach

Proteolysis Targeting Chimera (PROTAC) technology represents a promising new approach for target protein degradation using a cellular ubiquitin-proteasome system. Recently, we developed a split-and-mix nanoplatform based on peptide self-assembly, which could serve as a self-adjustable platform for multifunctional applications. However, the lower drug efficacy limits further biomedical applications of peptide-based SM-PROTAC. In this study, we develop a novel split-and-mix PROTAC system based on liposome self-assembly (LipoSM-PROTAC), concurrent with modification of FA (folate) to enhance its tumor-targeting capabilities. Estrogen receptors (ERα) were chosen as the protein of interest (POI) to validate the efficacy of Lipo degraders. Results demonstrate that this PROTAC can be efficiently and selectively taken up into the cells by FA receptor-positive cells (FR+) and degrade the POI with significantly reduced concentration. Compared to the peptide-based SM-PROTACs, our designed LipoSM-PROTAC system could achieve therapeutic efficacy with a lower concentration and provide opportunities for clinical translational potential. Overall, the LipoSM-based platform shows a higher drug efficacy, which offers promising potential applications for PROTAC and other biomolecule regulations.

Recent advances in lipid-based long-acting injectable depot formulations

Long-acting injectable (LAIs) delivery systems sustain the drug therapeutic action in the body, resulting in reduced dosage regimen, toxicity, and improved patient compliance. Lipid-based depots are biocompatible, provide extended drug release, and improve drug stability, making them suitable for systemic and localized treatment of various chronic ailments, including psychosis, diabetes, hormonal disorders, arthritis, ocular diseases, and cancer. These depots include oil solutions, suspensions, oleogels, liquid crystalline systems, liposomes, solid lipid nanoparticles, nanostructured lipid carriers, phospholipid phase separation gel, vesicular phospholipid gel etc. This review summarizes recent advancements in lipid-based LAIs for delivering small and macromolecules, and their potential in managing chronic diseases. It also provides an overview of the lipid depots available in market or clinical phase, as well as patents for lipid-based LAIs. Furthermore, this review critically discusses the current scenario of using in vitro release methods to establish IVIVC and highlights the challenges involved in developing lipid-based LAIs.

Tumor microenvironment stimuli-responsive lipid-drug conjugates for cancer treatment

Lipid drug conjugates (LDCs) have attracted considerable attention in the fields of drug delivery and pharmacology due to their ability to target specific cells, increase drug solubility, reduce toxicity, and improve therapeutic efficacy. These unique features make LDCs promising candidates for the treatment cancer, inflammation, and infectious diseases. In fact, by choosing specific linkers between the lipid and drug molecules, stimuli-responsive LDCs can be designed to target cancer cells based on the unique properties of the tumor microenvironment. Despite the fact that many reviews have described LDCs, few articles have focused on tumor microenvironmental stimuli-responsive LDCs for cancer treatment. Therefore, the key elements of these types of LDCs in cancer treatment will be outlined and discussed in this paper. Our paper goes into detail on the concepts and benefits of LDCs, the various types of tumor microenvironment stimuli-responsive LDCs (such as pH, redox, enzyme, or reactive oxygen species-responsive LDCs), and the current status of LDCs in clinical trials.

Piperine Liposome-Embedded in Hyaluronan Hydrogel as an Effective Platform for Prevention of Postoperative Peritoneal Adhesion

This study aimed to prepare piperine (PIP) loaded liposomes in hyaluronic acid (HA) hydrogel to provide a hybrid superstructure for postoperative adhesion prevention. Liposomes were prepared using thin-film hydration method. The optimised formulation was characterised by size, SEM, TEM, FTIR, encapsulation efficiency (EE)% (w/w), and release pattern. Liposome-in-hydrogel formulation was investigated by rheology, SEM, and release studies. The efficacy was evaluated in a rat peritoneal abrasion model. EE% (w/w) increased with increasing lipid concentration from 10 to 30; however, a higher percentage of Chol reduced EE% (w/w). The optimised liposome (EE: 68.10 ± 4.18% (w/w), average diameter: 513 ± 14.67 nm, PDI: 0.15 ± 0.04) was used for hydrogel embedding. No sign of adhesion in 5/8 rats and no collagen deposition confirmed the in vivo effectiveness of the optimised formulation. Overall, providing a sustained delivery of PIP, the developed liposome-in-hydrogel formulation can be a promising carrier to prevent postoperative adhesion.

Dehydroroyleanone as a Building Block for a Drug Delivery Platform Based on Self-Assembled Nanoparticles: Structural Studies and Chemical Modification

6,7-Dehydroroyleanone (DHR) is a caspase-induced cytotoxic abietane diterpene, frequently found on Plectranthus spp. A pharmaceutical formulation consisting of a DHR-squalene conjugate was synthesized and analyzed by different techniques such as scanning electron microscopy (SEM). The facile production of the dispersion of DHR-squalene conjugate nanoparticles in phosphate buffer (pH 7.4) suggests that this nanodelivery platform may be an effective system to improve the solubility and bioavailability of DHR, so that therapeutical systemic levels may be achieved.

Modified solid in oil nanodispersion containing vemurafenib-lipid complex- in vitro/ in vivo study

Background: Vemurafenib (VEM) was a licensed drug for the treatment of skin melanoma and is available only in the market as oral tablets prescribed in huge doses (1920 mg/day). One reason for the high dose is vemurafenib's low oral bioavailability. Methods: VEM-lipid complex (DLC) was predicted based on Conquest and Mercury programs and prepared using the solvent evaporation method using the lipid (phosphatidylethanolamine). DLC was subjected to characterization (FT-IR, Raman spectroscopy, DSC, TGA, P-XRD, and FESEM) to confirm complexation.  DLC was used to prepare solid in oil nanodispersion (DLC-SON) and subjected to in vitro, ex vivo, and in vivo evaluation in comparison to our recently prepared conventional SON (VEM-SON) and DLC-control. Results: Conquest and Mercury predict the availability of intermolecular hydrogen bonding between VEM and phosphatidylethanolamine (PE). All characterization tests of DLC ensure the complexation of the drug with PE. Ex vivo studies showed that the drug in DLC-SON has significantly (P<0.05) higher skin permeation than DLC-control but lower drug permeation than conventional SON but it has a higher % skin deposition (P<0.05) than others. The half-maximal inhibitory concentration (IC50) of the prepared DLC-SON is significantly high (P<0.05) in comparison to the conventional SON and pure VEM. In vivo permeation using confocal laser scanning microscopy (on the rat) results indicated that both conventional SON and DLC-SON can cross the SC and infiltrate the dermis and epidermis but DLC-SON has a higher luminance/gray value after 24 h in the dermis in comparison to the conventional SON. Conclusion: The novel lipid complex for VEM prepared using PE as a lipid and enclosed in SON showed higher anticancer activity and topical permeation as well as sustained delivery and good retention time in the dermis that localize the drug in a sufficient concentration to eliminate early diagnosed skin melanoma.

Lipid-mediated ex vivo cell surface engineering for augmented cellular functionalities

Once administrated, intercellular adhesion to recognize and/or arrest target cells is essential for specific treatments, especially for cancer or tumor. However, immune cells administrated into the tumor-microenvironment could lose their intrinsic functionalities such as target recognition ability, resulting in an ineffective cancer immunotherapy. Various manipulation techniques for decorating functional moieties onto cell surface and enhancing target recognition have been developed. A hydrophobic interaction-mediated ex-vivo cell surface engineering using lipid-based biomaterials could be a state-of-the-art engineering technique that could achieve high-efficiency cell surface modification by a single method without disturbance of intrinsic characteristics of cells. In this regard, this review provides design principles for the development of lipid-based biomaterials with a linear structure of lipid, polyethylene glycol, and functional group, strategies for the synthesis process, and their practical applications in biomedical engineering. Especially, we provide new insights into the development of a novel surface coating techniques for natural killer (NK) cells with engineering decoration of cancer targeting moieties on their cell surfaces. Among immune cells, NK cells are interesting cell population for substituting T cells because of their excellent safety and independent anticancer efficacy. Thus, optimal strategies to select cancer-type-specific targeting moieties and present them onto the surface of immune cells (especially, NK cells) using lipid-based biomaterials could provide additional tools to capture cancer cells for developing novel immune cell therapy products. Enhanced anticancer efficacies by surface-engineered NK cells have been demonstrated both in vitro and in vivo. Therefore, it could be speculated that recent progresses in cell surface modification technology via lipid-based biomaterials could strengthen immune surveillance and immune synapses for utilization in a next-generation cancer immunotherapy, beyond currently available genetic engineering tool such as chimeric antigen receptor-mediated immune cell modulation.

Modified solid in oil nanodispersion containing vemurafenib-lipid complex- in vitro/ in vivo study

Background: Vemurafenib (VEM) was a licensed drug for the treatment of skin melanoma and is available only in the market as oral tablets prescribed in huge doses (1920 mg/day). One reason for the high dose is vemurafenib's low oral bioavailability. Methods: VEM-lipid complex (DLC) was predicted based on Conquest and Mercury programs and prepared using the solvent evaporation method using the lipid (phosphatidylethanolamine). DLC was subjected to characterization (FT-IR, Raman spectroscopy, DSC, TGA, P-XRD, and FESEM) to confirm complexation.  DLC was used to prepare solid in oil nanodispersion (DLC-SON) and subjected to in vitro, ex vivo, and in vivo evaluation in comparison to our recently prepared conventional SON (VEM-SON) and DLC-control. Results: Conquest and Mercury predict the availability of intermolecular hydrogen bonding between VEM and phosphatidylethanolamine (PE). All characterization tests of DLC ensure the complexation of the drug with PE. Ex vivo studies showed that the drug in DLC-SON has significantly (P<0.05) higher skin permeation than DLC-control but lower drug permeation than conventional SON but it has a higher % skin deposition (P<0.05) than others. The half-maximal inhibitory concentration (IC50) of the prepared DLC-SON is significantly high (P<0.05) in comparison to the conventional SON and pure VEM. In vivo permeation using confocal laser scanning microscopy (on the rat) results indicated that both conventional SON and DLC-SON can cross the SC and infiltrate the dermis and epidermis but DLC-SON has a higher luminance/gray value after 24 h in the dermis in comparison to the conventional SON. Conclusion: The novel lipid complex for VEM prepared using PE as a lipid and enclosed in SON showed higher anticancer activity and topical permeation as well as sustained delivery and good retention time in the dermis that localize the drug in a sufficient concentration to eliminate early diagnosed skin melanoma.

Trichilia catigua and Turnera diffusa phyto-phospholipid nanostructures: physicochemical characterization and bioactivity in cellular models of induced neuroinflammation and neurotoxicity

Flavonoid-based therapies supported by nanotechnology are considered valuable strategies to prevent or delay age-related and chronic neurodegenerative disorders. Egg yolk phospholipids were combined with flavonoid-rich extracts obtained from Trichilia catigua A.Juss. (rich in flavan-3-ols and phenylpropanoid derivatives) or Turnera diffusa Willd. ex Schult (dominated by luteolin derivatives) to prepare nanophytosomes. The nanophytosomes showed that size and surface charge of the lipid-based vesicles are dependent of their phenolic composition. In vitro assays with SH-SY5Y cells showed that both formulations protect cells from glutamate-induced toxicity, but not from 6-hydroxydopamine/ascorbic acid. T. diffusa nanophytosomes promote a decrease of nitric oxide produced by BV-2 cells stimulated with interferon-γ. Nanophytosomes dialysed against a mannitol solution, and then lyophilised, allow to obtain freeze-dried products that after re-hydration preserve the essential physicochemical features of the original formulations, and exhibit improved colloidal stability. These results indicate that these flavonoid/phospholipid-based nanophytosomes have suitable features to be considered as tool in the development of therapeutic and food applications.

Squalene-Based Nano-Assemblies Improve the Pro-Autophagic Activity of Trehalose

The disaccharide trehalose is a well-established autophagy inducer, but its therapeutic application is severely hampered by its low potency and poor pharmacokinetic profile. Thus, we targeted the rational design and synthesis of trehalose-based small molecules and nano objects to overcome such issues. Among several rationally designed trehalose-centered putative autophagy inducers, we coupled trehalose via suitable spacers with known self-assembly inducer squalene to yield two nanolipid-trehalose conjugates. Squalene is known for its propensity, once linked to a bioactive compound, to assemble in aqueous media in controlled conditions, internalizing its payload and forming nanoassemblies with better pharmacokinetics. We assembled squalene conjugates to produce the corresponding nanoassemblies, characterized by a hydrodynamic diameter of 188 and 184 nm and a high stability in aqueous media as demonstrated by the measured Z-potential. Moreover, the nanoassemblies were characterized for their toxicity and capability to induce autophagy in vitro.

Fundamental Aspects of Lipid-Based Excipients in Lipid-Based Product Development

Poor aqueous solubility of drugs is still a foremost challenge in pharmaceutical product development. The use of lipids in designing formulations provides an opportunity to enhance the aqueous solubility and consequently bioavailability of drugs. Pre-dissolution of drugs in lipids, surfactants, or mixtures of lipid excipients and surfactants eliminate the dissolution/dissolving step, which is likely to be the rate-limiting factor for oral absorption of poorly water-soluble drugs. In this review, we exhaustively summarize the lipids excipients in relation to their classification, absorption mechanisms, and lipid-based product development. Methodologies utilized for the preparation of solid and semi-solid lipid formulations, applications, phase behaviour, and regulatory perspective of lipid excipients are discussed.

Broad-Spectrum Theranostics and Biomedical Application of Functionalized Nanomaterials

Nanotechnology is an important branch of science in therapies known as “nanomedicine” and is the junction of various fields such as material science, chemistry, biology, physics, and optics. Nanomaterials are in the range between 1 and 100 nm in size and provide a large surface area to volume ratio; thus, they can be used for various diseases, including cardiovascular diseases, cancer, bacterial infections, and diabetes. Nanoparticles play a crucial role in therapy as they can enhance the accumulation and release of pharmacological agents, improve targeted delivery and ultimately decrease the intensity of drug side effects. In this review, we discussthe types of nanomaterials that have various biomedical applications. Biomolecules that are often conjugated with nanoparticles are proteins, peptides, DNA, and lipids, which can enhance biocompatibility, stability, and solubility. In this review, we focus on bioconjugation and nanoparticles and also discuss different types of nanoparticles including micelles, liposomes, carbon nanotubes, nanospheres, dendrimers, quantum dots, and metallic nanoparticles and their crucial role in various diseases and clinical applications. Additionally, we review the use of nanomaterials for bio-imaging, drug delivery, biosensing tissue engineering, medical devices, and immunoassays. Understandingthe characteristics and properties of nanoparticles and their interactions with the biological system can help us to develop novel strategies for the treatment, prevention, and diagnosis of many diseases including cancer, pulmonary diseases, etc. In this present review, the importance of various kinds of nanoparticles and their biomedical applications are discussed in much detail.

Potential enhancement of metformin hydrochloride in solidified reverse micellar solution-based PEGylated lipid nanoparticles targeting therapeutic efficacy in diabetes treatment

Metformin hydrochloride (MH) is a widely used oral biguanide antihyperglycemic (antidiabetic) drug with poor bioavailability which necessitates the development of novel drug delivery systems such as PEGylated solid lipid nanoparticles for improving its therapeutic activity. The aim of this study was to formulate, characterize and evaluate in vitro and in vivo pharmacodynamic properties of metformin-loaded PEGylated solid lipid nanoparticles (PEG-SLN) for improved delivery of MH. The lipid matrices (non-PEGylated lipid matrix and PEGylated lipid matrices) used in the formulation of both non-PEGylated (J0) and PEGylated SLNs (J10, J20, J40) were prepared by fusion using beeswax and Phospholipon ® 90H at 7:3 ratio with or without polyethylene glycol (PEG) 4000 (0, 10, 20 and 40% w/w), respectively. Representative lipid matrices (LM and PEG-LM) were loaded with MH by fusion and then characterized by differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopy. The PEG-SLNs were prepared by high shear hot homogenization using the lipid matrices (5% w/w), drug (MH) (1.0% w/w), sorbitol (4% w/w) (cryoprotectant), Tween ® 80 (2% w/w) (surfactant) and distilled water (q.s to 100% w/w) (vehicle). The non-PEGylated and PEGylated SLNs (J0, J10, J20, J40)) were characterized with respect to encapsulation efficiency (EE%), loading capacity (LC), morphology by scanning electron microscopy (SEM), mean particle size (Zav) and polydispersity indices (PDI) by photon correlation spectroscopy (PCS), compatibility by FT-IR spectroscopy and in vitro drug release in biorelevant medium. Thereafter, in vivo antidiabetic study was carried out in alloxanized rats' model and compared with controls (pure sample of MH and commercial MH- Glucophage®)). Solid state characterizations indicated the amorphous nature of MH in the drug loaded-lipid matrices. The PEG-SLNs were mostly smooth and spherical nanoformulations with Zav and PDI of 350.00 nm and 0.54, respectively, for non-PEGylated SLNs, and in the range of 386.80-783.10 nm and 0.592 to 0.752, respectively, for PEGylated SLNs. The highest EE% and LC were noted in batch J20 and were 99.28% and 16.57, respectively. There was no strong chemical interaction between the drug and excipients used in the preparation of the formulations. The PEGylated SLN (batch J40) exhibited the highest percentage drug released (60%) at 8 h. The PEGylated SLNs showed greater hyperglycemic control than the marketed formulation (Glucophage ®) after 24 h. This study has shown that metformin-loaded PEGylated solid lipid nanoparticles could be employed as a potential approach to improve the delivery of MH in oral diabetic management, thus encouraging further development of the formulations.

Lipid Nanoparticles as a Promising Drug Delivery Carrier for Topical Ocular Therapy-An Overview on Recent Advances

Due to complicated anatomical and physical properties, targeted drug delivery to ocular tissues continues to be a key challenge for formulation scientists. Various attempts are currently being made to improve the in vivo performance of therapeutic molecules by encapsulating them in various nanocarrier systems or devices and administering them via invasive/non-invasive or minimally invasive drug administration methods. Biocompatible and biodegradable lipid nanoparticles have emerged as a potential alternative to conventional ocular drug delivery systems to overcome various ocular barriers. Lipid-based nanocarrier systems led to major technological advancements and therapeutic advantages during the last few decades of ocular therapy, such as high precorneal residence time, sustained drug release profile, minimum dosing frequency, decreased drug toxicity, targeted site delivery, and, therefore, an improvement in ocular bioavailability. In addition, such formulations can be given as fine dispersion in patient-friendly droppable preparation without causing blurred vision and ocular sensitivity reactions. The unique advantages of lipid nanoparticles, namely, solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions, and liposomes in intraocular targeted administration of various therapeutic drugs are extensively discussed. Ongoing and completed clinical trials of various liposome-based formulations and various characterization techniques designed for nanoemulsion in ocular delivery are tabulated. This review also describes diverse solid lipid nanoparticle preparation methods, procedures, advantages, and limitations. Functionalization approaches to overcome the drawbacks of lipid nanoparticles, as well as the exploration of new functional additives with the potential to improve the penetration of macromolecular pharmaceuticals, would quickly progress the challenging field of ocular drug delivery systems.

Nanocarrier-Based Approaches for the Efficient Delivery of Anti-Tubercular Drugs and Vaccines for Management of Tuberculosis

Drug-resistant species of tuberculosis (TB), which spread faster than traditiona TB, is a severely infectious disease. The conventional drug therapy used in the management of tuberculosis has several challenges linked with adverse effects. Hence, nanotherapeutics served as an emerging technique to overcome problems associated with current treatment. Nanotherapeutics helps to overcome toxicity and poor solubility issues of several drugs used in the management of tuberculosis. Due to their diameter and surface chemistry, nanocarriers encapsulated with antimicrobial drugs are readily taken up by macrophages. Macrophages play a crucial role as they serve as target sites for active and passive targeting for nanocarriers. The surface of the nanocarriers is coated with ligand-specific receptors, which further enhances drug concentration locally and indicates the therapeutic potential of nanocarriers. This review highlights tuberculosis's current facts, figures, challenges associated with conventional treatment, different nanocarrier-based systems, and its application in vaccine development.

Direct comparison of two kinds of linoleic acid-docetaxel derivatives: in vitro cytotoxicity and in vivo antitumor activity

Rational designed lipid-drug derivatives provide a favorable approach to improve the druggability of highly hydrophobic prototypes. It has been regarded as common sense that good cytotoxicity is the guarantee of superior anticancer efficacy for candidate derivatives screening. However, does it apply to lipid-drug conjugate-based self-assembled nanoparticles? Here, we established the above two derivatives and a non-correlation between the cytotoxic activity in vitro and drug efficacy in vivo was found. The IC₅₀ of DSL NPs (DTX-S-LA nanoparticles) and DL NPs (DTX-LA nanoparticles) were 4.02 and 209.6 ng/mL (DTX equivalent concentration), respectively. However, DL NPs unexpectedly showed stronger tumor inhibition abilities than DSL NPs. To explain the non-positive correlation between cytotoxicity and anticancer efficacy, more experiments were carried out in depth. Remarkably, the drug release studies in blood and PK study both suggested that the DL NPs were more stable to remain the structural integrity in circulation, which resulted in more accumulation in tumor sites. As verified by the bio-distribution study, DL NPs performed a superior target effect than DSL NPs in tumors. Our data indicated that the biological fates of so-called smart bond inserted derivatives in vivo are complicated; thus, simple cytotoxicity is not enough for derivatives screening, and the comprehensive understanding of both in vitro and in vivo behaviors is essential.

All-trans retinoic acid in anticancer therapy: how nanotechnology can enhance its efficacy and resolve its drawbacks

Introduction: All-trans retinoic acid (ATRA, tretinoin) is the main drug used in the treatment of acute promyelocytic leukemia (APL). Despite its impressive activity against APL, the same could not be clinically observed in other types of cancer. Nanotechnology can be a tool to enhance ATRA anticancer efficacy and resolve its drawbacks in APL as well as in other malignancies.Areas covered: This review covers ATRA use in APL and non-APL cancers, the problems that were found in ATRA therapy and how nanoencapsulation can aid to circumvent them. Pre-clinical results obtained with nanoencapsulated ATRA are shown as well as the two ATRA products based on nanotechnology that were clinically tested: ATRA-IV® and Apealea®.Expert opinion: ATRA presents interesting properties to be used in anticancer therapy with a notorious differentiation and antimetastatic activity. Bioavailability and resistance limitations impair the use of ATRA in non-APL cancers. Nanotechnology can circumvent these issues and provide tools to enhance its anticancer activities, such as co-loading of multiple drug and active targeting to tumor site.

Kinetically-stable small-molecule prodrug nanoassemblies for cancer chemotherapy

Self-delivering nanocarrier based on the small-molecule prodrug nanoassemblies (NAs) have been widely used for the efficient delivery of chemotherapeutics, but the effect of kinetic stability of NAs on their delivery performance has not been illuminated. In this study, two camptothecin (CPT)-oleic acid (OA) prodrugs were used to fabricate self-assembling nanorods with similar size distribution, zeta potential and morphology but having sharply different kinetic stability, which provided an ideal platform to investigate the effects of kinetic stability. It is found that the nanorods with high kinetic stability showed a lower in vitro cytotoxicity, but were more effective to inhibit the tumor growth probably by decreasing the premature CPT release and subsequent generation of the inactive carboxylate CPT. However, such kinetically stable nanorods also resulted in the increased toxicity, probably due to the high prodrug accumulation in tissues after multiple injections. These results outlined the pivotal role of kinetic stability in determining antitumor efficacy of prodrug NAs, which provided a new insight into the delivery mechanism for the small-molecule prodrug self-delivering nanosystems.

Advancement of nanoscience in development of conjugated drugs for enhanced disease prevention

Nanoscience and nanotechnology is a recently emerging and rapid developing field of science and has also been explored in the fields of Biotechnology and Medicine. Nanoparticles are being used as tools for diagnostic purposes and as a medium for the delivery of therapeutic agents to the specific targeted sites under controlled conditions. The physicochemical properties of these nanoparticles give them the ability to treat various chronic human diseases by site specific drug delivery and to use in diagnosis, biosensing and bioimaging devices, and implants. According to the type of materials used nanoparticles can be classified as organic (micelles, liposomes, nanogels and dendrimers) and inorganic (including gold nanoparticles (GNPs), super-paramagnetic iron oxide nanomaterials (SPIONs), quantum dots (QDs), and paramagnetic lanthanide ions). Different types of nanoparticle are being used in conjugation with various types of biomoities (such as peptide, lipids, antibodies, nucleotides, plasmids, ligands and polysaccharides) to form nanoparticle-drug conjugates which has enhanced capacity of drug delivery at targeted sites and hence improved disease treatment and diagnosis. In this study, the summary of various types of nanoparticle-drug conjugates that are being used along with their mechanism and applications are included. In addition, the various nanoparticle-drug conjugates which are being used and which are under clinical studies along with their future opportunities and challenges are also discussed in this review.

Monoolein-based nanoparticles containing indinavir: a taste-masked drug delivery system

OBJECTIVE

This study developed a novel child-friendly drug delivery system for pediatric HIV treatment: a liquid, taste-masked, and solvent-free monoolein-based nanoparticles formulation containing indinavir (0.1%).

SIGNIFICANCE

Adherence to antiretroviral therapy by pediatric patients is difficult because of the lack of dosage forms adequate for children.

METHODS

Monoolein-based nanoparticles were developed. The particle size, zeta potential, pH, drug content, small angle X-ray scattering, stability, in vitro drug release profile, biocompatibility, toxicity, and taste-masking properties were evaluated.

RESULTS

Monoolein-based formulations containing indinavir had nanosized particles with 155 ± 7 nm, unimodal particle size distribution, and polydispersity index of 0.16 ± 0.03. The zeta potential was negative (-31.3 ± 0.3 mV) and pH was neutral (7.78 ± 0.01). A 96% drug incorporation efficiency was achieved, and the indinavir concentration remained constant for 30 days. Polarized light microscopy revealed isotropic characteristics. Transmission electron microscopy images showed spherical shaped morphology. Small-angle X-ray scattering displayed a form factor broad peak. Indinavir had a sustained release from the nanoparticles. The system was nonirritant and was able to mask drug bitter taste.

CONCLUSIONS

Monoolein-based nanoparticles represent a suitable therapeutic strategy for antiretroviral treatment with the potential to reduce the frequency of drug administration and promote pediatric adherence.

Recent Progress in Bioconjugation Strategies for Liposome-Mediated Drug Delivery

In nanoparticle (NP)-mediated drug delivery, liposomes are the most widely used drug carrier, and the only NP system currently approved by the FDA for clinical use, owing to their advantageous physicochemical properties and excellent biocompatibility. Recent advances in liposome technology have been focused on bioconjugation strategies to improve drug loading, targeting, and overall efficacy. In this review, we highlight recent literature reports (covering the last five years) focused on bioconjugation strategies for the enhancement of liposome-mediated drug delivery. These advances encompass the improvement of drug loading/incorporation and the specific targeting of liposomes to the site of interest/drug action. We conclude with a section highlighting the role of bioconjugation strategies in liposome systems currently being evaluated for clinical use and a forward-looking discussion of the field of liposomal drug delivery.

Lipid-based Nanoplatforms in Cancer Therapy: Recent Advances and Applications

Though modern available cancer therapies are effective, they possess major adverse effects, causing non-compliance to patients. Furthermore, the majority of the polymeric-based medication platforms are certainly not universally acceptable, due to their several restrictions. With this juxtaposition, lipid-based medication delivery systems have appeared as promising drug nanocarriers to replace the majority of the polymer-based products because they are in a position to reverse polymer as well as, drug-associated restrictions. Furthermore, the amalgamation of the basic principle of nanotechnology in designing lipid nanocarriers, which are the latest form of lipid carriers, has tremendous chemotherapeutic possibilities as tumor-targeted drug-delivery pertaining to tumor therapy. Apart from this, it is reported that nearly 40% of the modern medication entities are lipophilic. Moreover, research continues to be efficient in attaining a significant understanding of the absorption and bioavailability of the developed lipids systems.

Carrier-free nanodrugs for safe and effective cancer treatment

Clinical applications of many anti-cancer drugs are restricted due to their hydrophobic nature, requiring use of harmful organic solvents for administration, and poor selectivity and pharmacokinetics resulting in off-target toxicity and inefficient therapies. A wide variety of carrier-based nanoparticles have been developed to tackle these issues, but such strategies often fail to encapsulate drug efficiently and require significant amounts of inorganic and/or organic nanocarriers which may cause toxicity problems in the long term. Preparation of nano-formulations for the delivery of water insoluble drugs without using carriers is thus desired, requiring elegantly designed strategies for products with high quality, stability and performance. These strategies include simple self-assembly or involving chemical modifications via coupling drugs together or conjugating them with various functional molecules such as lipids, carbohydrates and photosensitizers. During nanodrugs synthesis, insertion of redox-responsive linkers and tumor targeting ligands endows them with additional characteristics like on-target delivery, and conjugation with immunotherapeutic reagents enhances immune response alongside therapeutic efficacy. This review aims to summarize the methods of making carrier-free nanodrugs from hydrophobic drug molecules, evaluating their performance, and discussing the advantages, challenges, and future development of these strategies.

Strategies to Obtain Encapsulation and Controlled Release of Small Hydrophilic Molecules

The therapeutic effect of small hydrophilic molecules is limited by the rapid clearance from the systemic circulation or a local site of administration. The unsuitable pharmacokinetics and biodistribution can be improved by encapsulating them in drug delivery systems. However, the high-water solubility, very hydrophilic nature, and low molecular weight make it difficult to encapsulate small hydrophilic molecules in many drug delivery systems. In this mini-review, we highlight three strategies to efficiently encapsulate small hydrophilic molecules and achieve controlled release: physical encapsulation in micro/nanocapsules, physical adsorption via electronic interactions, and covalent conjugation. The principles, advantages, and disadvantages of each strategy are discussed. This review paper could be a guide for scientists, engineers, and medical doctors who want to improve the therapeutic efficacy of small hydrophilic drugs.

Novel Drug Delivery Systems for Loading of Natural Plant Extracts and Their Biomedical Applications

Many types of research have distinctly addressed the efficacy of natural plant metabolites used for human consumption both in cell culture and preclinical animal model systems. However, these in vitro and in vivo effects have not been able to be translated for clinical use because of several factors such as inefficient systemic delivery and bioavailability of promising agents that significantly contribute to this disconnection. Over the past decades, extraordinary advances have been made successfully on the development of novel drug delivery systems for encapsulation of plant active metabolites including organic, inorganic and hybrid nanoparticles. The advanced formulas are confirmed to have extraordinary benefits over conventional and previously used systems in the manner of solubility, bioavailability, toxicity, pharmacological activity, stability, distribution, sustained delivery, and both physical and chemical degradation. The current review highlights the development of novel nanocarrier for plant active compounds, their method of preparation, type of active ingredients, and their biomedical applications.

Lipid Vesicles and Nanoparticles for Non-invasive Topical and Transdermal Drug Delivery

The delivery of drugs, via different layers of skin, is challenging because it acts as a natural barrier and exerts hindrance against molecules to permeate into or through it. To overcome such obstacles, different noninvasive methods, like vehicle-drug interaction, modifications of the horny layer and nanoparticles have been suggested. The aim of the present review is to highlight some of the non-invasive methods for topical, diadermal and transdermal delivery of drugs. Special emphasis has been made on the information available in numerous research articles that put efforts in overcoming obstacles associated with barrier functions imposed by various layers of skin. Advances have been made in improving patient compliance that tends to avoid hitches involved in oral administration. Of particular interest is the use of lipid-based vesicles and nanoparticles for dermatological applications. These particulate systems can effectively interact and penetrate into the stratum corneum via lipid exchange and get distributed in epidermis and dermis. They also have the tendency to exert a systemic effect by facilitating the absorption of an active moiety into general circulation.

Lipid-drug conjugates and associated carrier strategies for enhanced antiretroviral drug delivery

Mortality rate of patients infected with HIV-1 has been significantly reduced by using HAART. However, the virus to date has not been eradicated. Transmission of HIV-1 infection through sexual intercourse remains an ongoing challenge, with increased risk of infection occurring in women. Interestingly, ARV drugs can be chemically linked with lipids to produce lipid-drug conjugates (LDCs). This alters pharmacokinetic properties of ARV drugs and thereby resulting in improved effectiveness. Although LDCs can be administered without a delivery carrier, they are usually incorporated into suitable delivery systems such as lipid nanoparticles, polymeric nanoparticles, micelles, liposomes, emulsions, and carbon nanotubes. Given that LDCs have the potential to improve oral bioavailability, lipophilicity, toxicity, and drug targeting, it is of our great interest to review strategies of lipid-drug conjugation together with their delivery systems for enhanced antiretroviral efficacy.

Nanolipid-Trehalose Conjugates and Nano-Assemblies as Putative Autophagy Inducers

The disaccharide trehalose is an autophagy inducer, but its pharmacological application is severely limited by its poor pharmacokinetics properties. Thus, trehalose was coupled via suitable spacers with squalene (in 1:2 and 1:1 stoichiometry) and with betulinic acid (1:2 stoichiometry), in order to yield the corresponding nanolipid-trehalose conjugates 1-Sq-mono, 2-Sq-bis and 3-Be-mono. The conjugates were assembled to produce the corresponding nano-assemblies (NAs) Sq-NA1, Sq-NA2 and Be-NA3. The synthetic and assembly protocols are described in detail. The resulting NAs were characterized in terms of loading and structure, and tested in vitro for their capability to induce autophagy. Our results are presented and thoroughly commented upon.

Liposome-ligand conjugates: a review on the current state of art

Early researchers focussed on developing stimuli-responsive liposomes in order to manipulate drug release at the site of action or under certain conditions. In recent times, a great deal of efforts has been made to modify the surface of liposomes with ligands for the purpose of achieving targeted drug delivery. Due to the morphology of liposomes, their surfaces can be engineered by attaching molecules such as oligosaccharides, peptides, antibodies, antigens and oligonucleotides to the bilayer structure. Over the years, a number of techniques including the use of covalent and non-covalent linkages have been utilised in designing ligand-liposome conjugates. In this review, various strategies for the functionalisation of liposomes as well as the different types of ligand-liposome conjugates have been discussed. Finally, the pros and cons of conjugation in liposomes are concisely summarised.

Cockle Shell-Derived Calcium Carbonate (Aragonite) Nanoparticles: A Dynamite to Nanomedicine

Cockle shell is an external covering of small, salt water edible clams (Anadara granosa) that dwells in coastal area. This abundant biomaterial is hard, cheap and readily available with high content of calcium carbonate in aragonite polymorphic form. At present, cockle shell-derived calcium carbonate nanoparticles (CSCaCO3NPs) with dual applications has remarkably drawn significant attention of researchers in nanotechnology as a nanocarrier for delivery of different categories of drugs and as bone scaffold due to its beneficial potentials such as biocompatibility, osteoconductivity, pH sensitivity, slow biodegradation, hydrophilic nature and a wide safety margin. In addition, CSCaCO3NP possesses structural porosity, a large surface area and functional group endings for electrostatic ion bonds with high loading capacity. Thus, it maintains great potential in the drug delivery system and a large number of biomedical utilisations. The pioneering researchers adopted a non-hazardous top-down method for the synthesis of CSCaCO3NP with subsequent improvements that led to the better spherical diameter size obtained recently which is suitable for drug delivery. The method is therefore a simple, low cost and environmentally friendly, which involves little procedural steps without stringent temperature management and expensive hazardous chemicals or any carbonation methods. This paper presents a review on a few different types of nanoparticles with emphasis on the versatile most recent advancements and achievements on the synthesis and developments of CSCaCO3NP aragonite with its applications as a nanocarrier for drug delivery in nanomedicine.

Drug-Lipid Conjugates for Enhanced Oral Drug Delivery

Oral drug delivery route is one of the most convenient and extensively utilised routes for drug administration. But there exists class of drugs which exhibit poor bioavailability on oral drug administration. Designing of drug-lipid conjugates (DLCs) is one of the rationale strategy utilised in overcoming this challenge. This review extensively covers the various dimensions of drug modification using lipids to attain improved oral drug delivery. DLCs help in improving oral delivery by providing benefits like improved permeability, stability in gastric environment, higher drug loading in carriers, formation of self-assembled nanostructures, etc. The clinical effectiveness of DLCs is highlighted from available marketed drug products along with many DLCs in phase of clinical trials. Conclusively, this drug modification strategy can potentially help in augmenting oral drug delivery in future.

Self-Assembled Nanomedicines for Anticancer and Antibacterial Applications

Self-assembly strategies have been widely applied in the nanomedicine field, which provide a convenient approach for building various structures for delivery carriers. When cooperating with biomolecules, self-assembly systems have significant influence on the cell activity and life process and could be used for regulating nanodrug activity. In this review, self-assembled nanomedicines are introduced, including materials, encapsulation, and releasing strategies, where self-assembly strategies are involved. Furthermore, as a promising and emerging area for nanomedicine, in situ self-assembly of anticancer drugs and supramolecular antibiotic switches is also discussed about how to regulate drug activity. Selective pericellular assembly can block mass transformation of cancer cells inducing cell apoptosis, and the intracellular assembly can either cause cell death or effectively avoid drug elimination from cytosol of cancer cells because of the assembly-induced retention (AIR) effect. Host-guest interactions of drug and competitive molecules offer reversible regulations of antibiotic activity, which can reduce drug-resistance and inhibit the generation of drug-resistant bacteria. Finally, the challenges and development trend in the field are discussed.