Dual-targeting for brain-specific liposomes drug delivery system: Synthesis and preliminary evaluation

Preparation and in vitro evaluation of tissue plasminogen activator-loaded nanoliposomes with anticoagulant coating

The clinical efficacy of tissue plasminogen activator (tPA) is limited by its lack of specific delivery, requiring large therapeutic doses that increase the risk of intracerebral hemorrhage, bleeding at the surgical site, and patient mortality after angioplasty. To address these limitations, this study aimed to develop a chitosan polysulfate (CsPs)-coated liposomal formulation for the sustained release of tPA. The CsPs-coated liposomes containing tPA (Liposome-tPA/CsPs) were fabricated using the thin-film hydration technique and their properties were compared to tPA-encapsulated nanoliposomes without a coating layer (Liposome-tPA). Liposome-tPA/CsPs showed a quasi-spherical morphology with a hydrodynamic diameter of 110 nm, while Liposome-tPA had a diameter of 80 nm. The thermal analysis showed that the degradation temperature and glass transition temperature (Tg) of Liposome-tPA/CsPs were higher than that of tPA alone, indicating improved temperature stability. The in vitro release study demonstrated a slow and sustained release of tPA from the Liposome-tPA/CsPs, with a concentration of 0.02 mg/ml at 1 h and 0.23 mg/ml at 180 h. The CsPs coating layer enhanced the antibacterial and antioxidant activity of the nanoliposomes. Liposome-tPA/CsPs exhibited higher cell viability compared to Liposome-tPA. It also achieved a higher percentage of thrombolysis, with complete clot dissolution observed after 3 h of treatment. These findings suggest that the Liposome-tPA/CsPs can be a promising approach to overcome the limitations associated with the systemic administration of tPA, potentially enhancing its clinical efficacy while reducing the risk of adverse events.

Small Scale, Big Impact: Nanotechnology-Enhanced Drug Delivery for Brain Diseases

Central nervous system (CNS) diseases, ranging from brain cancers to neurodegenerative disorders like dementia and acute conditions such as strokes, have been heavily burdening healthcare and have a direct impact on patient quality of life. A significant hurdle in developing effective treatments is the presence of the blood-brain barrier (BBB), a highly selective barrier that prevents most drugs from reaching the brain. The tight junctions and adherens junctions between the endothelial cells and various receptors expressed on the cells make the BBB form a nonfenestrated and highly selective structure that is crucial for brain homeostasis but complicates drug delivery. Nanotechnology offers a novel pathway to circumvent this barrier, with nanoparticles engineered to ferry drugs across the BBB, protect drugs from degradation, and deliver medications to the designated area. After years of development, nanoparticle optimization, including sizes, shapes, surface modifications, and targeting ligands, can enable nanomaterials tailored to specific brain drug delivery settings. Moreover, smart nano drug delivery systems can respond to endogenous and exogenous stimuli that control subsequent drug release. Here, we address the importance of the BBB in brain disease treatment, summarize different delivery routes for brain drug delivery, discuss the cutting-edge nanotechnology-based strategies for brain drug delivery, and further offer valuable insights into how these innovations in nanoparticle technology could revolutionize the treatment of CNS diseases, presenting a promising avenue for noninvasive, targeted therapeutic interventions.

An Overview on the Physiopathology of the Blood-Brain Barrier and the Lipid-Based Nanocarriers for Central Nervous System Delivery

The state of well-being and health of our body is regulated by the fine osmotic and biochemical balance established between the cells of the different tissues, organs, and systems. Specific districts of the human body are defined, kept in the correct state of functioning, and, therefore, protected from exogenous or endogenous insults of both mechanical, physical, and biological nature by the presence of different barrier systems. In addition to the placental barrier, which even acts as a linker between two different organisms, the mother and the fetus, all human body barriers, including the blood-brain barrier (BBB), blood-retinal barrier, blood-nerve barrier, blood-lymph barrier, and blood-cerebrospinal fluid barrier, operate to maintain the physiological homeostasis within tissues and organs. From a pharmaceutical point of view, the most challenging is undoubtedly the BBB, since its presence notably complicates the treatment of brain disorders. BBB action can impair the delivery of chemical drugs and biopharmaceuticals into the brain, reducing their therapeutic efficacy and/or increasing their unwanted bioaccumulation in the surrounding healthy tissues. Recent nanotechnological innovation provides advanced biomaterials and ad hoc customized engineering and functionalization methods able to assist in brain-targeted drug delivery. In this context, lipid nanocarriers, including both synthetic (liposomes, solid lipid nanoparticles, nanoemulsions, nanostructured lipid carriers, niosomes, proniosomes, and cubosomes) and cell-derived ones (extracellular vesicles and cell membrane-derived nanocarriers), are considered one of the most successful brain delivery systems due to their reasonable biocompatibility and ability to cross the BBB. This review aims to provide a complete and up-to-date point of view on the efficacy of the most varied lipid carriers, whether FDA-approved, involved in clinical trials, or used in in vitro or in vivo studies, for the treatment of inflammatory, cancerous, or infectious brain diseases.

Functionalized liposomes: an enticing nanocarrier for management of glioma

Glioma is one of the most severe central nervous systems (CNS)-specific tumors, with rapidly growing malignant glial cells accounting for roughly half of all brain tumors and having a poor survival rate ranging from 12 to 15 months. Despite being the most often used technique for glioma therapy, conventional chemotherapy suffers from low permeability of the blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB) to anticancer drugs. When it comes to nanocarriers, liposomes are thought of as one of the most promising nanocarrier systems for glioma treatment. However, owing to BBB tight junctions, non-targeted liposomes, which passively accumulate in most cancer cells primarily via the increased permeability and retention effect (EPR), would not be suitable for glioma treatment. The surface modification of liposomes with various active targeting ligands has shown encouraging outcomes in the recent times by allowing various chemotherapy drugs to pass across the BBB and BBTB and enter glioma cells. This review article introduces by briefly outlining the landscape of glioma, its classification, and some of the pathogenic causes. Further, it discusses major barriers for delivering drugs to glioma such as the BBB, BBTB, and tumor microenvironment. It further discusses modified liposomes such as long-acting circulating liposomes, actively targeted liposomes, stimuli responsive liposomes. Finally, it highlighted the limitations of liposomes in the treatment of glioma and the various actively targeted liposomes undergoing clinical trials for the treatment of glioma.

The Involvement of Ascorbic Acid in Cancer Treatment

Vitamin C (VC), also known as ascorbic acid, plays a crucial role as a water-soluble nutrient within the human body, contributing to a variety of metabolic processes. Research findings suggest that increased doses of VC demonstrate potential anti-tumor capabilities. This review delves into the mechanisms of VC absorption and its implications for cancer management. Building upon these foundational insights, we explore modern delivery systems for VC, evaluating its use in diverse cancer treatment methods. These include starvation therapy, chemodynamic therapy (CDT), photothermal/photodynamic therapy (PTT/PDT), electrothermal therapy, immunotherapy, cellular reprogramming, chemotherapy, radiotherapy, and various combination therapies.

Microfluidics-Prepared Ultra-small Biomimetic Nanovesicles for Brain Tumor Targeting

Blood-brain-barrier (BBB) serves as a fatal guard of the central nervous system as well as a formidable obstacle for the treatment of brain diseases such as brain tumors. Cell membrane-derived nanomedicines are promising drug carriers to achieve BBB-penetrating and brain lesion targeting. However, the challenge of precise size control of such nanomedicines has severely limited their therapeutic effect and clinical application in brain diseases. To address this problem, this work develops a microfluidic mixing platform that enables the fabrication of cell membrane-derived nanovesicles with precise controllability and tunability in particle size and component. Sub-100 nm macrophage plasma membrane-derived vesicles as small as 51 nm (nanoscale macrophage vesicles, NMVs), with a narrow size distribution (polydispersity index, PDI: 0.27) and a high drug loading rate (up to 89% for indocyanine green-loaded NMVs, NMVs@ICG (ICG is indocyanine green)), are achieved through a one-step process. Compared to beyond-100 nm macrophage cell membrane vesicles (general macrophage vesicles, GMVs) prepared via the traditional methods, the new NMVs exhibits rapid (within 1 h post-injection) and enhanced orthotopic glioma targeting (up to 78% enhancement), with no extra surface modification. This work demonstrates the great potential of such real-nanoscale cell membrane-derived nanomedicines in targeted brain tumor theranostics.

A Novel Quercetin Encapsulated Glucose Modified Liposome and Its Brain-Target Antioxidative Neuroprotection Effects

Neurodegenerative diseases (NDDs) are mainly induced by oxidative stress which produces excessive reactive oxygen species (ROS). Quercetin (QU) is a potent antioxidant with some effects on NDDs. This study prepared and characterized a novel glucose-modified QU liposome (QU-Glu-Lip), aiming not only to overcome QU's poor water solubility and bioavailability but also to deliver more QU to brain tissue to enhance its neuroprotective effect. QU-Glu-Lip possessed encapsulation efficiency (EE) of 89.9%, homogenous particle sizes (116-124 nm), small PDI value (<0.3), zeta value -1.363 ± 0.437 mV, proper pH and salt stability, and proper cytotoxicity. The glucose-modified liposome penetrated the blood-brain barrier (BBB) mediated via the glucose transporter 1 (GLUT1) and was taken by neuronal cells more efficiently than liposome without glucose, according to bEnd.3 and PC12 cell tests. QU-Glu-Lip attenuated H2O2-induced oxidative damage to PC12 with higher cell viability (88.42%) and lower intracellular ROS compared to that of QU. QU-Glu-Lip had higher brain target ability and delivered more QU to neuronal cells, effectively exerting the antioxidative neuroprotection effect. There is potential for the QU-Glu-Lip application for more effective treatment of NDDs.

Liposome-Mediated Anti-Viral Drug Delivery Across Blood-Brain Barrier: Can Lipid Droplet Target Be Game Changers?

Lipid droplets (LDs) are subcellular organelles secreted from the endoplasmic reticulum (ER) that play a major role in lipid homeostasis. Recent research elucidates additional roles of LDs in cellular bioenergetics and innate immunity. LDs activate signaling cascades for interferon response and secretion of pro-inflammatory cytokines. Since balanced lipid homeostasis is critical for neuronal health, LDs play a crucial role in neurodegenerative diseases. RNA viruses enhance the secretion of LDs to support various phases of their life cycle in neurons which further leads to neurodegeneration. Targeting the excess LD formation in the brain could give us a new arsenal of antiviral therapeutics against neuroviruses. Liposomes are a suitable drug delivery system that could be used for drug delivery in the brain by crossing the Blood-Brain Barrier. Utilizing this, various pharmacological inhibitors and non-coding RNAs can be delivered that could inhibit the biogenesis of LDs or reduce their sizes, reversing the excess lipid-related imbalance in neurons. Liposome-Mediated Antiviral Drug Delivery Across Blood-Brain Barrier. Developing effective antiviral drug is challenging and it doubles against neuroviruses that needs delivery across the Blood-Brain Barrier (BBB). Lipid Droplets (LDs) are interesting targets for developing antivirals, hence targeting LD formation by drugs delivered using Liposomes can be game changers.

Recent advances in drug delivery systems for targeting brain tumors

Brain tumor accounts for about 1.6% of incidence and 2.5% of mortality of all tumors, and the median survival for brain tumor patients is only about 20 months. The treatment for brain tumor still faces many challenges, such as the blood-brain barrier (BBB), blood-brain tumor barrier (BBTB), the overexpressed efflux pumps, the infiltration, invasion, high heterogeneity of tumor cells, drug resistance and immune escape caused by tumor microenvironment (TME) and cancer stem cells (CSC). This review attempts to clarify the challenges for multi-functional nano drug delivery systems (NDDS) to cross the BBB and target the cancer cells or organelles, and also provides a brief description of the different types of targeted multi-functional NDDS that have shown potential for success in delivering drugs to the brain. Further, this review also summarizes the research progress of multi-functional NDDS in the combination therapy of brain tumors from the following sections, the combination of chemotherapy drugs, chemotherapy-chemodynamic combination therapy, chemotherapy-immunization combination therapy, and chemotherapy-gene combination therapy. We also provide an insight into the recent advances in designing multi-functional NDDS for combination therapy.

Advances in antibody-based drugs and their delivery through the blood-brain barrier for targeted therapy and immunotherapy of gliomas

Gliomas are highly invasive and are the most common type of primary malignant brain tumor. The routine treatments for glioma include surgical resection, radiotherapy, and chemotherapy. However, glioma recurrence and patient survival remain unsatisfactory after employing these traditional treatment approaches. With the rapid development of molecular immunology, significant breakthroughs have been made in targeted glioma therapy and immunotherapy. Antibody-based therapy has excellent advantages in treating gliomas due to its high specificity and sensitivity. This article reviewed various targeted antibody drugs for gliomas, including anti-glioma surface marker antibodies, anti-angiogenesis antibodies, and anti-immunosuppressive signal antibodies. Notably, many antibodies have been validated clinically, such as bevacizumab, cetuximab, panitumumab, and anti-PD-1 antibodies. These antibodies can improve the targeting of glioma therapy, enhance anti-tumor immunity, reduce the proliferation and invasion of glioma, and thus prolong the survival time of patients. However, the existence of the blood-brain barrier (BBB) has caused significant difficulties in drug delivery for gliomas. Therefore, this paper also summarized drug delivery methods through the BBB, including receptor-mediated transportation, nano-based carriers, and some physical and chemical methods for drug delivery. With these exciting advancements, more antibody-based therapies will likely enter clinical practice and allow more successful control of malignant gliomas.

Laser thrombolysis and in vitro release kinetics of tPA encapsulated in chitosan polysulfate-coated nanoliposome

A major challenge in managing coronary artery disease is to find an effective thrombolytic therapy with minimal side effects. Laser thrombolysis is a practical procedure to remove the thrombus from inside blocked arteries, although it can cause embolism and re-occlusion of the vessel. The present study aimed to design a liposome drug delivery system for the controlled release of tissue plasminogen activator (tPA) and delivery of drug system into the thrombus by Nd:YAG laser at a wavelength of 532 nm for the treatment of arterial occlusive diseases. In this study, tPA encapsulated into the chitosan polysulfate-coated liposome (Lip/PSCS-tPA) was fabricated by a thin-film hydration technique. The particle size of Lip/tPA and Lip/PSCS-tPA was 88 and 100 nm, respectively. The release rate of tPA from Lip/PSCS-tPA was measured to be 35 % and 66 % after 24 h and 72 h, respectively. Thrombolysis through the delivery of Lip/PSCS-tPA into the thrombus during the laser irradiation was higher compared to irradiated thrombus without the nanoliposomes. The expression of IL-10 and TNF-α genes was studied by RT-PCR. The level of TNF-α for Lip/PSCS-tPA was lower than that of tPA, which can lead to improved cardiac function. Also, in this study, the thrombus dissolution process was studied using a rat model. After 4 h, the thrombus area in the femoral vein was significantly lower for groups treated with Lip/PSCS-tPA (5 %) compared to the groups treated with tPA alone (45 %). Thus, according to our results, the combination of Lip/PSCS-tPA and laser thrombolysis can be introduced as an appropriate technique for accelerating thrombolysis.

Emerging Materials, Wearables, and Diagnostic Advancements in Therapeutic Treatment of Brain Diseases

Among the most critical health issues, brain illnesses, such as neurodegenerative conditions and tumors, lower quality of life and have a significant economic impact. Implantable technology and nano-drug carriers have enormous promise for cerebral brain activity sensing and regulated therapeutic application in the treatment and detection of brain illnesses. Flexible materials are chosen for implantable devices because they help reduce biomechanical mismatch between the implanted device and brain tissue. Additionally, implanted biodegradable devices might lessen any autoimmune negative effects. The onerous subsequent operation for removing the implanted device is further lessened with biodegradability. This review expands on current developments in diagnostic technologies such as magnetic resonance imaging, computed tomography, mass spectroscopy, infrared spectroscopy, angiography, and electroencephalogram while providing an overview of prevalent brain diseases. As far as we are aware, there hasn't been a single review article that addresses all the prevalent brain illnesses. The reviewer also looks into the prospects for the future and offers suggestions for the direction of future developments in the treatment of brain diseases.

Lipid-based nanoparticles and RNA as innovative neuro-therapeutics

RNA-delivery is a promising tool to develop therapies for difficult to treat diseases such as neurological disorders, by silencing pathological genes or expressing therapeutic proteins. However, in many cases RNA delivery requires a vesicle that could effectively protect the molecule from bio-degradation, bypass barriers i.e., the blood brain barrier, transfer it to a targeted tissue and efficiently release the RNA inside the cells. Many vesicles such as viral vectors, and polymeric nanoparticles have been mentioned in literature. In this review, we focus in the discussion of lipid-based advanced RNA-delivery platforms. Liposomes and lipoplexes, solid lipid nanoparticles and lipid nanoparticles are the main categories of lipidic platforms for RNA-delivery to the central nervous systems (CNS). A variety of surface particles' modifications and routes of administration have been studied to target CNS providing encouraging results in vivo. It is concluded that lipid-based nanoplatforms will play a key role in the development of RNA neuro-therapies.

Liposomes: An emerging carrier for targeting Alzheimer's and Parkinson's diseases

The function of the brain can be affected by various factors that include infection, tumor, and stroke. The major disorders reported with altered brain function are Alzheimer's disease (AD), Parkinson's disease (PD), dementia, brain cancer, seizures, mental disorders, and other movement disorders. The major barrier in treating CNS disease is the blood-brain barrier (BBB), which protects the brain from toxic molecules, and the cerebrospinal fluid (CSF) barrier, which separates blood from CSF. Brain endothelial cells and perivascular elements provide an integrated cellular barrier, the BBB, which hamper the invasion of molecules from the blood to the brain. Even though many drugs are available to treat neurological disorders, it fails to reach the desired site with the required concentration. In this purview, liposomes can carry required concentrations of molecules intracellular by diverse routes such as carrier-mediated transport and receptor-mediated transcytosis. Surface modification of liposomes enables them to deliver drugs to various brain cells, including neurons, astrocytes, oligodendrocytes, and microglia. The research studies supported the role of liposomes in delivering drugs across BBB and in reducing the pathogenesis of AD and PD. The liposomes were surface-functionalized with various molecules to reach the cells intricated with the AD or PD pathogenesis. The targeted and sustained delivery of drugs by liposomes is disturbed due to the antibody formation, renal clearance, accelerated blood clearance, and complement activation-related pseudoallergy (CARPA). Hence, this review will focus on the characteristics, surface functionalization, drug loading, and biodistribution of liposomes respective to AD and PD. In addition, the alternative strategies to overcome immunogenicity are discussed briefly.

Investigation of functionalized nanoplatforms using branched-ligands with different chain lengths for glioblastoma targeting

Glioblastoma, a common malignancy of the central nervous system, which is the most destructive type of brain cancer. Clinical treatment remains a major challenge due to high infiltrative growth and the presence of the blood brain barrier (BBB). Therefore, advanced nanoplatforms that can efficiently cross the BBB and target to brain tumor are highly desired. Compared with the targeting efficiency of single ligand nanoplatforms, dual targeting nanoplatforms may lead to better and controllable malignant cell selectivity. In this study, based on our previous research of branched ligands, we finally determined to use tri-branched glucose and two-branched biotin as targeting molecules, and in order to explore the synergetic-targeting capabilities and the mutual influence between the length of the two ligands, we designed three kinds of two-branched biotin ligands with different linker, and co-modified with the tri-branched glucose ligands on the surface of liposomes. The results of in vivo and in vitro experiments showed the (Glu₃+Bio₂)-2-Lip can exert the greatest synergistic targeting ability. The application of branched ligands, the dual-targeting design concept, and the exploration of the interaction between the chain lengths of the two ligands have brought new ideas and new methods for the targeted therapy of glioma.

Combinatorial therapeutic strategies for enhanced delivery of therapeutics to brain cancer cells through nanocarriers: current trends and future perspectives

Brain cancer is the most aggressive one among various cancers. It has a drastic impact on people's lives because of the failure in treatment efficacy of the currently employed strategies. Various strategies used to relieve pain in brain cancer patients and to prolong survival time include radiotherapy, chemotherapy, and surgery. Nevertheless, several inevitable limitations are accompanied by such treatments due to unsatisfactory curative effects. Generally, the treatment of cancers is very challenging due to many reasons including drugs’ intrinsic factors and physiological barriers. Blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB) are the two additional hurdles in the way of therapeutic agents to brain tumors delivery. Combinatorial and targeted therapies specifically in cancer show a very promising role where nanocarriers’ based formulations are designed primarily to achieve tumor-specific drug release. A dual-targeting strategy is a versatile way of chemotherapeutics delivery to brain tumors that gets the aid of combined ligands and mediators that cross the BBB and reaches the target site efficiently. In contrast to single targeting where one receptor or mediator is targeted, the dual-targeting strategy is expected to produce a multiple-fold increase in therapeutic efficacy for cancer therapy, especially in brain tumors. In a nutshell, a dual-targeting strategy for brain tumors enhances the delivery efficiency of chemotherapeutic agents via penetration across the blood-brain barrier and enhances the targeting of tumor cells. This review article highlights the ongoing status of the brain tumor therapy enhanced by nanoparticle based delivery with the aid of dual-targeting strategies. The future perspectives in this regard have also been highlighted.

Targeting Transporters for Drug Delivery to the Brain: Can We Do Better?

Limited drug delivery to the brain is one of the major reasons for high failure rates of central nervous system (CNS) drug candidates. The blood–brain barrier (BBB) with its tight junctions, membrane transporters, receptors and metabolizing enzymes is a main player in drug delivery to the brain, restricting the entrance of the drugs and other xenobiotics. Current knowledge about the uptake transporters expressed at the BBB and brain parenchymal cells has been used for delivery of CNS drugs to the brain via targeting transporters. Although many transporter-utilizing (pro)drugs and nanocarriers have been developed to improve the uptake of drugs to the brain, their success rate of translation from preclinical development to humans is negligible. In the present review, we provide a systematic summary of the current progress in development of transporter-utilizing (pro)drugs and nanocarriers for delivery of drugs to the brain. In addition, we applied CNS pharmacokinetic concepts for evaluation of the limitations and gaps in investigation of the developed transporter-utilizing (pro)drugs and nanocarriers. Finally, we give recommendations for a rational development of transporter-utilizing drug delivery systems targeting the brain based on CNS pharmacokinetic principles.

pH-redox responsive cascade-targeted liposomes to intelligently deliver doxorubicin prodrugs and lonidamine for glioma

To synergistically treat glioma with a combination chemotherapy, we design and prepare novel cascade-targeted liposomes (Lip-TPGS) using glucose and triphenylphosphonium (TPP) as targeting moieties, which could intelligently deliver redox-sensitive doxorubicin (DOX) prodrugs (SDOX) and chemotherapeutic sensitizer lonidamine (LND). The pH-responsive ligand Chol-TPG modified by PEGylated glucose can overcome the blood-brain barrier and reach tumor cells. Combined with the modification of mitochondria targeting ligand (Chol-TPP), Lip-TPGS are endowed with pH-responsive charge regulation function and multi-stage targeting abilities. After triggered by the excessive glutathione in tumor cells, Lip-TPGS could sufficiently release the parent drugs DOX, which would significantly reduce side effects without compromising anti-glioma efficacy. Therefore, Lip-TPGS possess these characteristics: good pharmacokinetic behavior, superior brain targeting ability, specific tumor recognition and internalization capability, and strong endo/lysosome escaping and mitochondria targeting potential. Furthermore, Lip-TPGS exhibit significant advantages on anti-glioma by inhibiting proliferation, promoting apoptosis, inducing mitochondria dysfunction, inhibiting migration and invasion, prolonging the survival time, narrowing tumor areas, limiting lung metastasis, and reducing toxicity to normal organs. In summary, Lip-TPGS, with cascade targeting abilities from tissue/cell to organelle levels and highly controlled drug release properties, would become a promising drug delivery system for glioma treatment.

Nanotechnology-based drug delivery for the treatment of CNS disorders

Approximately 6.8 million people die annually because of problems related to the central nervous system (CNS), and out of them, approximately 1 million people are affected by neurodegenerative diseases that include Alzheimer's disease, multiple sclerosis, epilepsy, and Parkinson's disease. CNS problems are a primary concern because of the complexity of the brain. There are various drugs available to treat CNS disorders and overcome problems with toxicity, specificity, and delivery. Barriers like the blood-brain barrier (BBB) are a challenge, as they do not allow therapeutic drugs to cross and reach their target. Researchers have been searching for ways to allow drugs to pass through the BBB and reach the target sites. These problems highlight the need of nanotechnology to alter or manipulate various processes at the cellular level to achieve the desired attributes. Due to their nanosize, nanoparticles are able to pass through the BBB and are an effective alternative to drug administration and other approaches. Nanotechnology has the potential to improve treatment and diagnostic techniques for CNS disorders and facilitate effective drug transfer. With the aid of nanoengineering, drugs could be modified to perform functions like transference across the BBB, altering signaling pathways, targeting specific cells, effective gene transfer, and promoting regeneration and preservation of nerve cells. The involvement of a nanocarrier framework inside the delivery of several neurotherapeutic agents used in the treatment of neurological diseases is reviewed in this study.

A Triple Combination of Targeting Ligands Increases the Penetration of Nanoparticles across a Blood-Brain Barrier Culture Model

Nanosized drug delivery systems targeting transporters of the blood-brain barrier (BBB) are promising carriers to enhance the penetration of therapeutics into the brain. The expression of solute carriers (SLC) is high and shows a specific pattern at the BBB. Here we show that targeting ligands ascorbic acid, leucine and glutathione on nanoparticles elevated the uptake of albumin cargo in cultured primary rat brain endothelial cells. Moreover, we demonstrated the ability of the triple-targeted nanovesicles to deliver their cargo into midbrain organoids after crossing the BBB model. The cellular uptake was temperature- and energy-dependent based on metabolic inhibition. The process was decreased by filipin and cytochalasin D, indicating that the cellular uptake of nanoparticles was partially mediated by endocytosis. The uptake of the cargo encapsulated in triple-targeted nanoparticles increased after modification of the negative zeta potential of endothelial cells by treatment with a cationic lipid or after cleaving the glycocalyx with an enzyme. We revealed that targeted nanoparticles elevated plasma membrane fluidity, indicating the fusion of nanovesicles with endothelial cell membranes. Our data indicate that labeling nanoparticles with three different ligands of multiple transporters of brain endothelial cells can promote the transfer and delivery of molecules across the BBB.

Multiple targeted doxorubicin-lonidamine liposomes modified with p-hydroxybenzoic acid and triphenylphosphonium to synergistically treat glioma

A type of pH-sensitive multi-targeted brain tumor site-specific liposomes (Lip-CTPP) co-modified with p-hydroxybenzoic acid (p-HA) and triphenylphosphonium (TPP) were designed and prepared to co-load doxorubicin (DOX) and lonidamine (LND). Lip-CTPP are promising potential carriers to exert the anti-glioma effect of DOX and LND collaboratively given the following features: 1) Lip-CTPP have a good pharmacokinetic behavior; 2) Lip-CTPP can cross the blood-brain barrier (BBB) and recognize tumor cells through the affinity of p-HA and dopamine/sigma receptors; 3) Lip-CTPP are highly positive charged once the acid-sensitive amide bonds are cleaved in endo/lysosomes to expose TPP and protonate amine groups; 4) the positive charged Lip-CTPP escape from endo/lysosomes and accumulate in mitochondria through electrostatic adsorption; 5) DOX and LND are released and synergistically increase anti-tumor efficacy. Our in vitro and in vivo results confirmed that Lip-CTPP could greatly elevate the inhibition rate of tumor cell proliferation, migration and invasion, promote apoptosis and necrosis, and interfere with mitochondrial function. In addition, Lip-CTPP could significantly prolong the survival time of glioma bearing mice, narrow the tumor region and inhibit the infiltration and metastasis capability of glioma cells. Collectively, Lip-CTPP are promising nano formulations to enhance the synergistic effect of DOX and LND in glioma treatment.

Fructose and biotin co-modified liposomes for dual-targeting breast cancer

Chemotherapy, as the main treatment for breast cancer, inevitably damages normal tissues due to the lack of targeting. Various nano targeting drug delivery systems (TDDS) have the potential to be developed as anticancer therapeutics. Although mono-ligand-directed liposomes have been used with some success, dual-ligand-directed liposomes exhibit promising advantages. In current work, we synthesized a Y-shaped ligand covalently linking fructose and biotin (Fru-Bio-Chol) to prepare a dual-targeting liposome Fru-Bio-Lip for breast cancer. The targeting ability was evaluated by comparing the Fru-Bio-Lip with the non-modified liposome (Lip), fructose or biotin mono modified liposomes (Fru-Lip and Bio-Lip), and another dual-targeting liposome (Fru + Bio-Lip) physically mixing fructose and biotin mono modified ligands (Fru-Chol and Bio-Chol). The cellular uptake of Fru-Bio-Lip is 3.27-, 1.81-, 2.19-, 1.15-times that of Lip, Fru-Lip, Bio-Lip and Fru + Bio-Lip on 4T1 cells, and 3.11-, 1.80-, 1.89-, 1.15-times on MCF-7 cells. Additionally, the uptake mechanism indicates the uptake of Fru-Bio-Lip is energy-dependently achieved through multiple endocytosis pathway with a dual recognition of fructose and biotin by GLUT₅ and SMVT. The cytotoxicity and apoptosis assay show PTX-Fru-Bio-Lip among liposomes have the strongest proliferation inhibitory effect on breast cancer cells, and the apoptosis rate is 1.7-times that of PTX-Lip. In vivo images indicate Fru-Bio-Lip have the strongest tumour enrichment ability, which is 2.76-, 1.60-, 1.96-, 1.40-times that of Lip, Fru-Lip, Bio-Lip and Fru + Bio-Lip, respectively. Overall, the fructose and biotin covalently modified liposomes improved breast cancer targeting ability, demonstrating great potential as a drug delivery system for breast cancer.

Understanding Drug Delivery to the Brain Using Liposome-Based Strategies: Studies that Provide Mechanistic Insights Are Essential

Brain drug delivery may be restricted by the blood-brain barrier (BBB), and enhancement by liposome-based drug delivery strategies has been investigated. As access to the human brain is limited, many studies have been performed in experimental animals. Whereas providing interesting data, such studies have room for improvement to provide mechanistic insight into the rate and extent of specifically BBB transport and intrabrain distribution processes that all together govern CNS target delivery of the free drug. This review shortly summarizes BBB transport and current liposome-based strategies to overcome BBB transport restrictions, with the emphasis on how to determine the individual mechanisms that all together determine the time course of free drug brain concentrations, following their administration as such, and in liposomes. Animal studies using microdialysis providing time course information on unbound drug in plasma and brain are highlighted, as these provide the mechanistic information needed to understand BBB drug transport of the drug, and the impact of a liposomal formulations of that drug on BBB transport. Overall, these studies show that brain distribution of a drug administered as liposomal formulation depends on both drug properties and liposomal formulation characteristics. In general, evidence suggests that active transporters at the BBB, either being influx or efflux transporters, are circumvented by liposomes. It is concluded that liposomal formulations may provide interesting changes in BBB transport. More mechanistic studies are needed to understand relevant mechanisms in liposomal drug delivery to the brain, providing an improved basis for its prediction in human using animal data.

Glucose and Triphenylphosphonium Co-Modified Redox-Sensitive Liposomes to Synergistically Treat Glioma with Doxorubicin and Lonidamine

Glioma is one of the most lethal and complex tumors, and thus, an effective drug delivery system must selectively target the tumor sites and release its cargos in a controlled manner. For the first time, we combined chemotherapeutic agent doxorubicin (DOX) and chemosensitizer lonidamine (LND) to synergistically treat glioma. We also designed and prepared multitargeted redox-sensitive liposomes (Lip-SPG) co-modified with glucose and triphenylphosphonium (TPP) to effectively deliver DOX and LND for anti-glioma therapy. The anti-glioma evaluation shows that DOX and LND have a synergistic effect and Lip-SPG could further enhance their cooperation. In vitro, Lip-SPG could increase the cellular uptake and mitochondrial uptake on bEnd.3 cells and C6 cells with multitargeting ability on the brain, tumor, and mitochondria mediated by glucose and TPP. Lip-SPG can also escape from lysosomes before entering the mitochondria. The anti-glioma efficacy in vitro shows that Lip-SPG can inhibit tumor cell proliferation and induce apoptosis. In addition, Lip-SPG have a remarkable interference to mitochondria, such as reducing intracellular ATP production, inducing ROS generation, and promoting mitochondrial membrane potential depolarization. Furthermore, in vivo, the introduction of PEGylation via glutathione-sensitive disulfide bonds endows Lip-SPG with favorable pharmacokinetic properties, brain targeting ability, low toxicity to normal tissues, and great anti-glioma efficacy with the survival time extended from 19 to 39 days. In conclusion, Lip-SPG are an effective delivery system for synergistically treating glioma with DOX and LND.

Dual-Targeting and Stimuli-Triggered Liposomal Drug Delivery in Cancer Treatment

The delivery of chemotherapeutics to solid tumors using smart drug delivery systems (SDDSs) takes advantage of the unique physiology of tumors (i.e., disordered structure, leaky vasculature, abnormal extracellular matrix (ECM), and limited lymphatic drainage) to deliver anticancer drugs with reduced systemic side effects. Liposomes are the most promising of such SDDSs and have been well investigated for cancer therapy. To improve the specificity, bioavailability, and anticancer efficacy of liposomes at the diseased sites, other strategies such as targeting ligands and stimulus-sensitive liposomes have been developed. This review highlights relevant surface functionalization techniques and stimuli-mediated drug release for enhanced delivery of anticancer agents at tumor sites, with a special focus on dual functionalization and design of multistimuli responsive liposomes.

Targeted Drug Delivery: Trends and Perspectives

BACKGROUND

Due to various limitations in conventional drug delivery system, it is important to focus on the target-specific drug delivery system where we can deliver the drug without any degradation. Among various challenges faced by a formulation scientist, delivering the drug to its right site, in its right dose, is also an important aim. A focused drug transport aims to extend, localize, target and have a safe drug interaction with the diseased tissue.

OBJECTIVE

The aim of targeted drug delivery is to make the required amount of the drug available at its desired site of action. Drug targeting can be accomplished in a number ways that include enzyme mediation, pH-dependent release, use of special vehicles, receptor targeting among other mechanisms. Intelligently designed targeted drug delivery systems also offer the advantages of a low dose of the drug along with reduced side effects which ultimately improves patient compliance. Incidences of dose dumping and dosage form failure are negligible. A focused drug transport aims to have a safe drug interaction with the diseased tissue.

CONCLUSION

This review focuses on the available targeting techniques for delivery to the colon, brain and other sites of interest. Overall, the article should make an excellent read for the researchers in this area. Newer drug targets may be identified and exploited for successful drug targeting.

Highlights in targeted nanoparticles as a delivery strategy for glioma treatment

Glioma is the most common type of Central Nervous System (CNS) neoplasia and it arises from glial cells. As glial cells are formed by different types of cells, glioma can be classified according to the cells that originate it or the malignancy grade. Glioblastoma multiforme is the most common and aggressive glioma. The high lethality of this tumor is related to the difficulty in performing surgical removal, chemotherapy, and radiotherapy in the CNS. To improve glioma treatment, a wide range of chemotherapeutics have been encapsulated in nanosystems to increase their ability to overcome the blood-brain barrier (BBB) and specifically reach the tumoral cells, reducing side effects and improving drug concentration in the tumor microenvironment. Several studies have investigated nanosystems covered with targeting ligands (e.g., proteins, peptides, aptamers, folate, and glucose) to increase the ability of drugs to cross the BBB and enhance their specificity to glioma through specific recognition by receptors on BBB and glioma cells. This review addresses the main targeting ligands used in nanosystems to overcome the BBB and promote the active targeting of drugs for glioma. Furthermore, the advantages of using these molecules in glioma treatment are discussed.

Prospects and challenges of anticancer agents' delivery via chitosan-based drug carriers to combat breast cancer: a review

Breast cancer (BC) is considered as one the most prevalent cancers worldwide. Due to its high resistance to chemotherapy and high probability of metastasis, BC is one of the leading causes of cancer-related deaths. The controlled release of chemotherapy drugs to the precise site of the tumor tissue will increase the therapeutic efficacy and decrease side effects of systemic administration. Among various drug delivery systems, natural polymers-based drug carriers have gained significant attention for cancer therapy. Chitosan, a natural polymer obtained by de-acetylation of chitin, holds huge potential for drug delivery applications because chitosan is non-toxic, non-immunogenic, biocompatible, chemically modifiable, and can be processed to form various formulations. In the current review, we will discuss the prospects and challenges of chitosan-based drug delivery systems in treating BC.

An update on actively targeted liposomes in advanced drug delivery to glioma

High-grade glioma is one of the most aggressive types of cancer with a low survival rate ranging from 12 to 15 months after the first diagnosis. Though being the most common strategy for glioma therapy, conventional chemotherapy suffers providing the therapeutic dosage of common therapeutics mostly because of limited permeability of blood-brain barrier (BBB), and blood-brain tumor barrier (BBTB) to anticancer agents. Among various nanoformulations, liposomes are considered as the most popular carriers aimed for glioma therapy. However, non-targeted liposomes which passively accumulate in most of the cancer tissues mainly through the enhanced permeation and retention effect (EPR), may not be applicable for glioma therapy due to BBB tight junctions. In the recent decade, the surface modification of liposomes with different active targeting ligands has shown promising results by getting different chemotherapeutics across the BBB and BBTB and leading them into the glioma cells. The present review discusses the major barriers for drug delivery systems to glioma, elaborates the existing mechanisms for liposomes to traverse across the BBB, and explores the main strategies for incorporation of targeting ligands onto the liposomes. It subsequently investigates the most recent and relevant studies of actively targeted liposomes modified with antibodies, aptamers, monosaccharides, polysaccharides, proteins, and peptides applied for effective glioma therapy, and highlights the common challenges facing this area. Finally, the actively targeted liposomes undergoing preclinical and clinical studies for delivery of different anticancer agents to glioma cells will be reviewed.

Synthesis of Nanoscale Liposomes via Low-Cost Microfluidic Systems

We describe the manufacture of low-cost microfluidic systems to produce nanoscale liposomes with highly uniform size distributions (i.e., low polydispersity indexes (PDI)) and acceptable colloidal stability. This was achieved by exploiting a Y-junction device followed by a serpentine micromixer geometry to facilitate the diffusion between the mixing phases (i.e., continuous and dispersed) via advective processes. Two different geometries were studied. In the first one, the microchannels were engraved with a laser cutting machine on a polymethyl methacrylate (PMMA) sheet and covered with another PMMA sheet to form a two-layer device. In the second one, microchannels were not engraved but through-hole cut on a PMMA sheet and encased by a top and a bottom PMMA sheet to form a three-layer device. The devices were tested out by putting in contact lipids dissolved in alcohol as the dispersed phase and water as the continuous phase to self-assemble the liposomes. By fixing the total flow rate (TFR) and varying the flow rate ratio (FRR), we obtained most liposomes with average hydrodynamic diameters ranging from 188 ± 61 to 1312 ± 373 nm and 0.30 ± 0.09 PDI values. Such liposomes were obtained by changing the FRR from 5:1 to 2:1. Our results approached those obtained by conventional bulk synthesis methods such as a thin hydration bilayer and freeze-thaw, which produced liposomes with diameters ranging from 200 ± 38 to 250 ± 38 nm and 0.30 ± 0.05 PDI values. The produced liposomes might find several potential applications in the biomedical field, particularly in encapsulation and drug delivery.

Biotin and glucose co-modified multi-targeting liposomes for efficient delivery of chemotherapeutics for the treatment of glioma

Glioma is one of the most common primary intracranial tumor, but the current treatments of glioma are far from satisfying. As the major treatment option for malignant glioma, chemotherapy has its own disadvantages, including low chemotherapeutic agents delivery across blood-brain barrier (BBB) and lack of specificity. Therefore, new approach permitting glioma targeting ability that can allow an efficient therapeutic delivery into the glioma regions is urgently required. Ligand-mediated liposomes have shown great potential for improving the efficiency of glioma treatment. In our study, the multi-targeting liposomes based on glucose and biotin were constructed for the first time. We synthesized two ligands (Glu₃-Chol, Bio₂-Chol), prepared three types of modified liposomes (Glu₃-Lip, Bio₂-Lip and Bio₂ + Glu₃-Lip) and evaluated the glioma-targeting ability of these liposomes which were using paclitaxel (PTX) as the model drug in vitro. Besides, the uptake mechanism of Bio₂ + Glu₃-Lip was investigated. PTX-loaded Bio₂ + Glu₃-Lip (PTX-Bio₂ + Glu₃-Lip) exhibited satisfactory targeting effect in Bend.3 and C6 cells in vitro, in which the cellular uptake of Bio₂ + Glu₃-Lip were 4.04- and 3.49-fold more than that of the uncoated liposomes (Lip). The results suggested the multi-targeting liposomes (Bio₂ + Glu₃-Lip) is a promising formulation for glioma, which was almost consistent with the results of in vivo imaging. In summary, we have designed and fabricated an effective delivery system to treat glioma.

Revisiting the blood-brain barrier: A hard nut to crack in the transportation of drug molecules

Barriers are the hallmark of a healthy physiology, blood-brain barrier (BBB) being a tough nut to crack for most of the antigens and chemical substances. The presence of tight junctions plays a remarkable role in defending the brain from antigenic and pathogenic attacks. BBB constitutes a diverse assemblage of multiple physical and chemical barriers that judiciously restrict the flux of blood solutes into and out of the brain. Restrictions through the paracellular pathway and the tight junctions between intercellular clefts, together create well regulated metabolic and transport barricades, critical to brain pathophysiology. The brain being impermeable to many essential metabolites and nutrients regulates transportation via specialized transport systems across the endothelial abluminal and luminal membranes. The epithelial cells enveloping capillaries of the choroid plexus regulates the transport of complement, growth factors, hormones, microelements, peptides and trace elements into ventricles. Nerve terminals, microglia, and pericytes associated with the endothelium support barrier induction and function, ensuring an optimally stable ionic microenvironment that facilitates neurotransmission, orchestrated by multiple ion channels (Na⁺, K⁺ Mg²⁺, Ca²⁺) and transporters. Brain pathology which can develop due to genetic mutations or secondary to other cerebrovascular, neurodegenerative diseases can cause aberration in the microvasculature of CNS which is the uniqueness of BBB. This can also alter BBB permeation and result in BBB breakdown and other neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis. The concluding section outlines contemporary trends in drug discovery, focusing on molecular determinants of BBB permeation and novel drug-delivery systems, such as dendrimers, liposomes, nanoparticles, nanogels, etc.

Biotin and glucose dual-targeting, ligand-modified liposomes promote breast tumor-specific drug delivery

Breast cancer is the second leading cause of cancer-related deaths in women. Ligand-modified liposomes are used for breast tumor-specific drug delivery to improve the efficacy and reduce the side effects of chemotherapy; however, only a few liposomes with high targeting efficiency have been developed because the mono-targeting, ligand-modified liposomes are generally unable to deliver an adequate therapeutic dose. In this study, we designed biotin-glucose branched ligand-modified, dual-targeting liposomes (Bio-Glu-Lip) and evaluated their potential as a targeted chemotherapy delivery system in vitro and in vivo. When compared with the non-targeting liposome (Lip), Bio-Lip, and Glu-Lip, Bio-Glu-Lip had the highest cell uptake in 4T1 cells (3.00-fold, 1.60-fold, and 1.95-fold higher, respectively) and in MCF-7 cells (2.63-fold, 1.63-fold, and 1.85-fold higher, respectively). The subsequent cytotoxicity and in vivo assays further supported the dual-targeting liposome is a promising drug delivery carrier for the treatment of breast cancer.

Breaking Barriers: Bioinspired Strategies for Targeted Neuronal Delivery to the Central Nervous System

Central nervous system (CNS) disorders encompass a vast spectrum of pathological conditions and represent a growing concern worldwide. Despite the high social and clinical interest in trying to solve these pathologies, there are many challenges to bridge in order to achieve an effective therapy. One of the main obstacles to advancements in this field that has hampered many of the therapeutic strategies proposed to date is the presence of the CNS barriers that restrict the access to the brain. However, adequate brain biodistribution and neuronal cells specific accumulation in the targeted site also represent major hurdles to the attainment of a successful CNS treatment. Over the last few years, nanotechnology has taken a step forward towards the development of therapeutics in neurologic diseases and different approaches have been developed to surpass these obstacles. The versatility of the designed nanocarriers in terms of physical and chemical properties, and the possibility to functionalize them with specific moieties, have resulted in improved neurotargeted delivery profiles. With the concomitant progress in biology research, many of these strategies have been inspired by nature and have taken advantage of physiological processes to achieve brain delivery. Here, the different nanosystems and targeting moieties used to achieve a neuronal delivery reported in the open literature are comprehensively reviewed and critically discussed, with emphasis on the most recent bioinspired advances in the field. Finally, we express our view on the paramount challenges in targeted neuronal delivery that need to be overcome for these promising therapeutics to move from the bench to the bedside.

The Pharmacokinetics of Vitamin C

The pharmacokinetics of vitamin C (vitC) is indeed complex. Regulated primarily by a family of saturable sodium dependent vitC transporters (SVCTs), the absorption and elimination are highly dose-dependent. Moreover, the tissue specific expression levels and subtypes of these SVCTs result in a compartmentalized distribution pattern with a diverse range of organ concentrations of vitC at homeostasis ranging from about 0.2 mM in the muscle and heart, and up to 10 mM in the brain and adrenal gland. The homeostasis of vitC is influenced by several factors, including genetic polymorphisms and environmental and lifestyle factors such as smoking and diet, as well as diseases. Going from physiological to pharmacological doses, vitC pharmacokinetics change from zero to first order, rendering the precise calculation of dosing regimens in, for example, cancer and sepsis treatment possible. Unfortunately, the complex pharmacokinetics of vitC has often been overlooked in the design of intervention studies, giving rise to misinterpretations and erroneous conclusions. The present review outlines the diverse aspects of vitC pharmacokinetics and examines how they affect vitC homeostasis under a variety of conditions.

Dual-active targeting liposomes drug delivery system for bone metastatic breast cancer: Synthesis and biological evaluation

Bone is the most common organ affected by metastatic breast cancer. Targeting cancers within the bone remains a great challenge due to the inefficient delivery of therapeutic to bone. In order to increase the distribution of paclitaxel (PTX) in bone metastases, in this study, a novel bone-targeted glutamic oligopeptides-RGD peptide (Glu₆-RGD) derivative was designed and synthesized as liposome ligand for preparing liposome to effectively deliver PTX to bone metastases. The liposome was prepared and its particle size, zeta potential, encapsulation efficiency, release profile, stability, hemolysis and cytotoxicity were also characterized. What's more, the Glu₆-RGD-Lip showed superior targeting ability in vitro and in vivo evaluation as compared to naked PTX, non-coated, singly-modified and co-modified by physical blending liposomes. All the results suggested that Glu₆-RGD-modified liposome showed excellent targeting activity to metastatic bone cancer. This study may be conducive to the field of bone-targeting drugs delivery.

Neuronanomedicine: An Up-to-Date Overview

The field of neuronanomedicine has recently emerged as the bridge between neurological sciences and nanotechnology. The possibilities of this novel perspective are promising for the diagnosis and treatment strategies of severe central nervous system disorders. Therefore, the development of nano-vehicles capable of permeating the blood⁻brain barrier (BBB) and reaching the brain parenchyma may lead to breakthrough therapies that could improve life expectancy and quality of the patients diagnosed with brain disorders. The aim of this review is to summarize the recently developed organic, inorganic, and biological nanocarriers that could be used for the delivery of imaging and therapeutic agents to the brain, as well as the latest studies on the use of nanomaterials in brain cancer, neurodegenerative diseases, and stroke. Additionally, the main challenges and limitations associated with the use of these nanocarriers are briefly presented.

Blood-Brain Delivery Methods Using Nanotechnology

Pathologies of the brain, of which brain cancer, Alzheimer's disease, Parkinson's disease, stroke, and multiple sclerosis, are some of the most prevalent, and that presently are poorly treated due to the difficulties associated with drug development, administration, and targeting to the brain. The existence of the blood-brain barrier, a selective permeability system which acts as a local gateway against circulating foreign substances, represents the key challenge for the delivery of therapeutic agents to the brain. However, the development of nanotechnology-based approaches for brain delivery, such as nanoparticles, liposomes, dendrimers, micelles, and carbon nanotubes, might be the solution for improved brain therapies.

Nanodelivery systems for overcoming limited transportation of therapeutic molecules through the blood-brain barrier

Due to the impermeable structure and barrier function of the blood-brain barrier (BBB), the delivery of therapeutic molecules into the CNS is extremely limited. Nanodelivery systems are regarded as the most effective and versatile carriers for the CNS, as they can transport cargo molecules across the BBB via various mechanisms. This review emphasizes the multi-functionalization strategies of nanodelivery systems and combinatorial approaches for the delivery of therapeutic drugs and genes into the CNS. The characteristics and functions of the BBB and underlying mechanisms of molecular translocation across the BBB are also described.