PEG-Detachable Polymeric Micelles Self-Assembled from Amphiphilic Copolymers for Tumor-Acidity-Triggered Drug Delivery and Controlled Release

Design, Synthesis, and Acid-Responsive Disassembly of Shell-Sheddable Block Copolymer Labeled with Benzaldehyde Acetal Junction

Smart nanoassemblies degradable through the cleavage of acid-labile linkages have attracted significant attention because of their biological relevance found in tumor tissues. Despite their high potential to achieve controlled/enhanced drug release, a systematic understanding of structural factors that affect their pH sensitivity remains challenging, particulary in the consruction of effective acid-degradable shell-sheddable nanoassemblies. Herein, the authors report the synthesis and acid-responsive degradation through acid-catalyzed hydrolysis of three acetal and ketal diols and identify benzaldehyde acetal (BzAA) exhibiting optimal hydrolysis profiles in targeted pH ranges to be a suitable candidate for junction acid-labile linkage. The authors explore the synthesis and aqueous micellization of well-defined poly(ethylene glycol)-based block copolymer bearing BzAA linkage covalently attached to a polymethacrylate block for the formation of colloidally-stable nanoassemblies with BzAA groups at core/corona interfaces. Promisingly, the investigation on acid-catalyzed hydrolysis and disassembly shows that the formed nanoassemblies meet the criteria for acid-degradable shell-sheddable nanoassemblies: slow degradation at tumoral pH = 6.5 and rapid disassembly at endo/lysosomal pH = 5.0, while colloidal stability at physiological pH = 7.4. This work guides the design principle of acid-degradable shell-sheddable nanoassemblies bearing BzAA at interfaces, thus offering the promise to address the PEG dilemma and improve endocytosis in tumor-targeting drug delivery.

Magnetic targeting and pH-microwave dual responsive Janus mesoporous silica nanoparticles for drug encapsulation and delivery

In this paper, a new Janus-structured nano drug delivery carrier Fe3O4@TiO2&mSiO2was designed and synthesized, which consisted of a spherical head and a closely connected rod. The head was a nanocomposite of core/shell structure with magnetic spinel ferric tetraoxide core and anatase titanium dioxide shell (Fe3O4@TiO2), and the rod was ordered mesoporous silica (mSiO2). The nanocarriers showed excellent magnetic targeting capability (saturation magnetization, 25.18 emu g-1). The core/shell heads endowed the carriers with fine microwave responsiveness. The pore volume of mesoporous nanocarriers was 0.101 cm3g-1, and the specific surface area was 489.0 m2g-1. Anticancer drug doxorubicin could be loaded in the mesoporous of the carriers to form Fe3O4@TiO2&mSiO2-DOX. The drug loading capacity was 10.4%. Fe3O4@TiO2&mSiO2-DOX exhibited acid-sensitive and microwave-sensitive release properties along with good bio-compatibility. Fe3O4@TiO2&mSiO2Janus nanoparticles are expected to be ideal drug carriers.

Carbosilane Dendritic Amphiphiles from Cholesterol or Vitamin E for Micelle Formation

Cationic dendritic amphiphiles were prepared through the linkage of interesting hydrophobic molecules such as cholesterol or vitamin E to the focal point of carbosilane dendrons. These new dendritic systems self-assembled in saline, producing micellar aggregates with hydrodynamic diameters ranging from 6.5 to 9.2 nm, and critical micelle concentrations of approximately 5 and 10 μM for second- and third-generation systems, respectively. The assemblies were able to encapsulate drugs of different charges (anionic, neutral, and cationic). Surprisingly, a 92% encapsulation efficiency for diclofenac was achieved in micelles prepared from second-generation dendrons. Toxicity measurements on peripheral blood mononuclear cells indicated different behavior depending on the generation, corresponding to the micellar regime. In contrast to the third-generation system, the second-generation system was non-toxic up to 20 μM, opening a window for its use in a micellar regimen, thereby operating as a drug delivery system for different biomedical applications.

Mitochondrial topoisomerase 1 targeted anticancer therapy using irinotecan encapsulated mesoporous MIL-101(Fe) synthesized via a vapour assisted method

Mitochondrial topisomerase 1 (Top1mt) is critical for mtDNA replication, transcription, and energy production. Here, we investigate the carrier-mediated targeted delivery of the anticancer drug irinotecan into the mitochondria to selectively trap Top1mt covalent complexes (Top1mtcc) and its role in anticancer therapeutics. We have designed a biocompatible mesoporous metal-organic framework (MOF) material, namely MIL-101(Fe), as the drug delivery carrier that selectively localizes inside mitochondria. In contrast to the traditional way of synthesising MOFs, here we have employed a vapour-assisted solvothermal method for the synthesis of MIL-101(Fe) using terephthalic acid as the organic linker and Fe(III) as the metal source. The advantage of this method is that it recycles the excess solvent (DMF) and reduces the amount of washing solvent. We demonstrate that MIL-101(Fe)-encapsulated irinotecan (MIL-Iri) was selectively targeted towards the mitochondria to poison Top1mtcc in a dose-dependent manner and was achieved at a low nanomolar drug concentration. We provide evidence that Top1mtcc generated by MIL-Iri leads to mtDNA damage in human colon and breast cancer cells and plays a significant role in cellular toxicity. Altogether, this study provides evidence for a new and effective strategy in anticancer chemotherapy.

Photoacid Generators for Biomedical Applications

Photoacid generators (PAGs) are compounds capable of producing hydrogen protons (H+ ) upon irradiation, including irreversible and reversible PAGs, which have been widely studied in photoinduced polymerization and degradation for a long time. In recent years, the applications of PAGs in the biomedical field have attracted more attention due to their promising clinical value. So, an increasing number of novel PAGs have been reported. In this review, the recent progresses of PAGs for biomedical applications is systematically summarized, including tumor treatment, antibacterial treatment, regulation of protein folding and unfolding, control of drug release and so on. Furthermore, a concept of water-dependent reversible photoacid (W-RPA) and its antitumor effect are highlighted. Eventually, the challenges of PAGs for clinical applications are discussed.

The spatiotemporal journey of nanomedicines in solid tumors on their therapeutic efficacy

The rapid development of nanomedicines is revolutionizing the landscape of cancer treatment, while effectively delivering them into solid tumors remains a formidable challenge. Currently, there is a huge disconnect on therapeutic response between regulatory approved nanomedicines and laboratory reported nanoparticles. The discrepancy is mainly resulted from the failure of using the classic overall pharmacokinetics behaviors of nanomedicines in tumors to predict the antitumor efficacy. Increasing evidence has revealed that the therapeutic efficacy predominantly relies on the intratumoral spatiotemporal distribution of nanomedicines. This review focuses on the spatiotemporal distribution of systemically administered chemotherapeutic nanomedicines in solid tumor. Firstly, the intratumoral biological barriers that regulate the spatiotemporal distribution of nanomedicines are described in detail. Next, the influences on antitumor efficacy caused by the spatial distribution and temporal drug release of nanomedicines are emphatically analyzed. Then, current methodologies for evaluating the spatiotemporal distribution of nanomedicines are summarized. Finally, the advanced strategies to positively modulate the spatiotemporal distribution of nanomedicines for an optimal tumor therapy are comprehensively reviewed.

Formulation of DOX-dimer with bi-functionalized chitooligosaccharide for tumor-specific self-boosted drug release and synergistic chemo/chemodynamic therapy

The toxic side effects and possible drug resistance of the chemotherapeutics hinder their antitumor efficacy. Here, a pH/reactive oxygen species (ROS) dual-triggered nanodrug was developed for the tumor-specific self-boosted drug release and synergistic chemo/chemodynamic therapy, by formulating ROS-cleavable doxorubicin (DOX)-based dimer (DOX-TK-DOX) with bi-functionalized chitooligosaccharide (COS-Fc-TK) with ferrocenecarboxylic acid (Fc) and thioketal (TK). The resultant DOX-TK-DOX/COS-Fc-TK nanoparticles with a high DOX content of 39.70 % showed tumor-specific self-boosted drug release, which was triggered by highly toxic OH generated via Fc-catalyzed Fenton reaction of the endogenous H2O2 in tumor intracellular microenvironment. As a result, a synergistic chemo/chemodynamic therapy with combination index (CI) of 0.94 was achieved for selective treatment of tumors.

Ultrasound-responsive glycopolymer micelles for targeted dual drug delivery in cancer therapy

Controlled drug release of nanoparticles was achieved by irreversibly disrupting polymer micelles through high-intensity focused ultrasound (HIFU) induction. An ultrasound-responsive block copolymer was synthesized, comprising an end-functional Eosin Y fluorophore, 2-tetrahydropyranyl acrylate (THPA), and acrylate mannose (MAN). The block copolymer was then self-assembled to produce micelles. The chemotherapy drug dasatinib (DAS) and the sonodynamic therapy agent methylene blue (MB) were encapsulated by the self-assembly of the block copolymer. This targeted nanoparticle enables sonodynamic therapy through high-intensity focused ultrasound while triggering nanoparticle disassembly for controlled drug release. The ultrasound-mediated, non-invasive strategy provides external spatiotemporal control for targeted tumour treatment.

Fabrication of Molecular Blocks with High Responsiveness to the Cancer Microenvironment by Ursodeoxycholic Acid

In cancer therapy, a drug delivery system (DDS) has been widely studied to achieve selective drug accumulation at the tumor site. However, DDS still has a major drawback in that it requires multistep processes for intracellular delivery, resulting in low efficiency of drug delivery. To overcome this problem, we recently reported a molecular block (MB) that disrupts cancer cell membranes in the cancer microenvironment using deoxycholic acid (DCA). However, the MB showed considerable cytotoxicity even at neutral pH, possibly due to the structural hydrophobic property of DCA. Herein, we focused on selecting the most suitable bile acid for an MB that possessed high responsiveness to the cancer microenvironment without cytotoxicity at neutral pH. Cell viabilities of the free bile acids such as DCA, chenodeoxycholic acid (CDCA), cholic acid (CA), and ursodeoxycholic acid (UDCA) were evaluated at neutral pH (pH = 7.4) and a cancer acidic environment (pH = 6.3-6.5). The half-maximal inhibition concentration (IC₅₀) value of UDCA at pH = 7.4 showed an approximately 7.5-fold higher IC₅₀ value than that at pH = 6.3, whereas the other bile acids yielded less than a 4-fold IC₅₀ value difference between the same pHs. Biocompatible poly(vinyl alcohol) (PVA) was functionalized with UDCA (PVA-UDCA) for the synthesis of higher responsiveness to the cancer microenvironment without cytotoxicity at neutral pH. Importantly, 56% pancreatic cancer cell death was observed at pH = 6.5, whereas only 10% was detected at neutral pH by the PVA-UDCA treatment. However, PVA-DCA indicated almost the same cancer cell death property, independent of pH conditions. These results suggest PVA-UDCA shows great potential for a new class of MB.

Mechanisms of Resistance and Current Treatment Options for Glioblastoma Multiforme (GBM)

Glioblastoma multiforme (GBM) is a highly aggressive form of brain cancer that is difficult to treat due to its resistance to both radiation and chemotherapy. This resistance is largely due to the unique biology of GBM cells, which can evade the effects of conventional treatments through mechanisms such as increased resistance to cell death and rapid regeneration of cancerous cells. Additionally, the blood–brain barrier makes it difficult for chemotherapy drugs to reach GBM cells, leading to reduced effectiveness. Despite these challenges, there are several treatment options available for GBM. The standard of care for newly diagnosed GBM patients involves surgical resection followed by concurrent chemoradiotherapy and adjuvant chemotherapy. Emerging treatments include immunotherapy, such as checkpoint inhibitors, and targeted therapies, such as bevacizumab, that attempt to attack specific vulnerabilities in GBM cells. Another promising approach is the use of tumor-treating fields, a type of electric field therapy that has been shown to slow the growth of GBM cells. Clinical trials are ongoing to evaluate the safety and efficacy of these and other innovative treatments for GBM, intending to improve with outcomes for patients.

Controlling self-assembling co-polymer coatings of hydrophilic polysaccharide substrates via co-polymer block length ratio

HYPOTHESIS

The degree of polymerization of amphiphilic di-block co-polymers, which can be varied with ease in computer simulations, provides a means to control self-assembling di-block co-polymer coatings on hydrophilic substrates.

SIMULATIONS

We examine self-assembly of linear amphiphilic di-block co-polymers on hydrophilic surface via dissipative particle dynamics simulations. The system models a glucose based polysaccharide surface on which random co-polymers of styrene and n-butyl acrylate, as the hydrophobic block, and starch, as the hydrophilic block, forms a film. Such setups are common in e.g. hygiene, pharmaceutical, and paper product applications.

FINDINGS

Variation of the block length ratio (35 monomers in total) reveals that all examined compositions readily coat the substrate. However, strongly asymmetric block co-polymers with short hydrophobic segments are best in wetting the surface, whereas approximately symmetric composition leads to most stable films with highest internal order and well-defined internal stratification. At intermediate asymmetries, isolated hydrophobic domains form. We map the sensitivity and stability of the assembly response for a large variety of interaction parameters. The reported response persists for a wide polymer mixing interactions range, providing general means to tune surface coating films and their internal structure, including compartmentalization.

Recent progress and applications of poly(beta amino esters)-based biomaterials

Poly(beta-amino esters, PBAEs) are a promising class of cationic polymers synthesized from diacrylates and amines via Michael addition. Recently, PBAEs have been widely developed for drug delivery, immunotherapy, gene therapy, antibacterial, tissue engineering and other applications due to their convenient synthesis, good bio-compatibility and degradation properties. Herein, we mainly summarize the recent progress in the PBAEs synthesis and their applications. The amine groups of PBAEs could be protonated in low pH environment, exhibiting proton sponge and pH-sensitive abilities. Furthermore, the positive PBAEs can interact with negative genes via electrostatic interactions for efficient delivery of nucleic acids. Moreover, positive PBAEs could also directly kill bacteria by disrupting their membranes at high doses. Finally, PBAEs can augment the immune responses, and improve the bioactivity of hydrogels in tissue engineering.

Nucleic acid drug vectors for diagnosis and treatment of brain diseases

Nucleic acid drugs have the advantages of rich target selection, simple in design, good and enduring effect. They have been demonstrated to have irreplaceable superiority in brain disease treatment, while vectors are a decisive factor in therapeutic efficacy. Strict physiological barriers, such as degradation and clearance in circulation, blood-brain barrier, cellular uptake, endosome/lysosome barriers, release, obstruct the delivery of nucleic acid drugs to the brain by the vectors. Nucleic acid drugs against a single target are inefficient in treating brain diseases of complex pathogenesis. Differences between individual patients lead to severe uncertainties in brain disease treatment with nucleic acid drugs. In this Review, we briefly summarize the classification of nucleic acid drugs. Next, we discuss physiological barriers during drug delivery and universal coping strategies and introduce the application methods of these universal strategies to nucleic acid drug vectors. Subsequently, we explore nucleic acid drug-based multidrug regimens for the combination treatment of brain diseases and the construction of the corresponding vectors. In the following, we address the feasibility of patient stratification and personalized therapy through diagnostic information from medical imaging and the manner of introducing contrast agents into vectors. Finally, we take a perspective on the future feasibility and remaining challenges of vector-based integrated diagnosis and gene therapy for brain diseases.

Production of paclitaxel-loaded PEG-b-PLA micelles using PEG for drug loading and freeze-drying

A new approach named PEG-assist is introduced for the production of drug-loaded polymeric micelles. The method is based on the use of PEG as the non-selective solvent for PEG-b-PLA in the fabrication procedure. Both hydration temperature and PEG molecular weight are shown to have a significant effect on the encapsulation efficiency of PTX in PEG_4kDa-b-PLA_2kDa micelles. The optimal procedure for fabrication includes the use of PEG_1kDa as the solvent at 60 °C, cooling the mixture to 40 °C, hydration at 40 °C, freezing at -80 °C and freeze-drying at -35 °C, 15 Pa. No significant difference (p > 0.05) in PTX encapsulation, average particle size and polydispersity index is observed between the samples before freeze-drying and after reconstitution of the freeze-dried cake. The prepared PTX formulations are stable at room temperature for at least 8 h. Scaling the batch size to 25× leads to no significant change (p > 0.05) in PTX encapsulation, average particle size and polydispersity index. PEG-assist method is applicable to other drugs such as 17-AAG, and copolymers of varied molecular weights. The use of no organic solvent, simplicity, cost-effectiveness, and efficiency makes PEG-assist a very promising approach for large scale production of drug-loaded polymeric micelles.

Charge-Convertible and Reduction-Sensitive Cholesterol-Containing Amphiphilic Copolymers for Improved Doxorubicin Delivery

For achieving successful chemotherapy against cancer, designing biocompatible drug delivery systems (DDSs) with long circulation times, high cellular endocytosis efficiency, and targeted drug release is of upmost importance. Herein, a well-defined PEG-b-P(MASSChol-co-MANBoc) block copolymer bearing redox-sensitive cholesteryl-side group was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization (with non-redox PEG-b-P(MACCChol-co-MAN-DCA) as the reference), and 1,2-dicarboxylic-cyclohexene acid (DCA) was then grafted onto the hydrophobic block to endow it with charge-convertible characteristics under a tumor microenvironment. The amphiphilic copolymer could be assembled into polymeric spherical micelles (SSMCs) with polyethylene glycol (PEG) as the corona/shell, and anti-cancer drug doxorubicin (DOX) was successfully encapsulated into the micellar core via strong hydrophobic and electrostatic interactions. This nanocarrier showed high stability in the physiological environment and demonstrated "smart" surface charge conversion from negative to positive in the slightly acidic environment of tumor tissues (pH 6.5~6.8), as determined by dynamic light scattering (DLS). Moreover, the cleavage of a disulfide bond linking the cholesterol grafts under an intracellular redox environment (10 mM GSH) resulted in micellar dissociation and accelerated drug release, with the non-redox-responsive micelles (CCMCs) as the control. Additionally, a cellular endocytosis and tumor proliferation inhibition study against MCF-7 tumor cells demonstrated the enhanced endocytosis and tumor cell inhibitory efficiency of dual-responsive SSMCs/DOX nanomedicines, revealing potentials as multifunctional nanoplatforms for effective oncology treatment.

Sperm-like nanocarriers for ultrafast delivery of antisense DNA

Although various nanomaterials have been designed as intracellular delivery tools, the following aspects have become obstacles to limit their development, like a complex and time-consuming synthesis process, as well as relatively limited application areas (i.e. biosensing or cell imaging). Here, we developed a novel nano-delivery system called "nano-sperm" with low cytotoxicity and high biocompatibility. In this system, we used DNA oligonucleotides as a backbone to synthesize a nanostructure with silver nanoclusters in the head and functional fragments in the tail, which is shaped like a sperm, to achieve dual functions of ultrafast delivery and imaging/therapy. As a model, we analyzed the possibility of the "nano-sperm" carrying DNA with different structures for imaging or survivin-asDNA for tumor therapy. Therefore, this work reports a novel bifunctional high-speed delivery vehicle, which successfully fills the gap in the field of tumor therapy using DNA-templated nanoclusters as a delivery vehicle.

Phosphorylcholine zwitterionic shell-detachable mixed micelles for enhanced cancerous cellular uptakes and increased DOX release

To further enhance the cancerous cellular uptakes and increase the drug release of the drug loaded micelles, herein, we fabricated a series of mixed micelles with different mass ratios using two amphiphilic copolymers P(DMAEMA-co-MaPCL) and PCL-SS-PMPC. The mixed micelles showed a prolonged circulation time due to the zwitterionic shells in a physiological environment (pH 7.4). In addition, because of the protonation of tertiary amine groups in PDMAEMA and the breakage of the disulfide bond in PMPC-SS-PCL in a tumor microenvironment, the mixed micelles aggregated, which led to enhanced cancerous cellular penetration and increased DOX release. Moreover, cytotoxicity assay showed that the mixed micelles had good biocompatibility to L929, HeLa and MCF-7 cells, even at a concentration of up to 1 mg mL^-1. Furthermore, enhanced antitumour activity and cellular uptake of HeLa and MCF-7 cells were detected after loading with DOX, which was determined by confocal laser scanning microscopy (CLSM) and flow cytometry (FC), especially for the DOX@MIX 3 micelles (20% mass ratio of the P(DMAEMA-co-MaPCL)). Therefore, the mixed strategy provides a simple and efficient ways to promote anticancer drug delivery.

Polycatechol-Derived Mesoporous Polydopamine Nanoparticles for Combined ROS Scavenging and Gene Interference Therapy in Inflammatory Bowel Disease

Benefiting from the evolution of nanotechnology, the combination therapy by gene interference and reactive oxygen species (ROS) scavenging are expected, which holds great potential in inflammatory bowel disease (IBD) therapy. However, the functional integration of different therapeutic modules through interface modification of gene vectors for safe and efficient treatment is urgently needed. Herein, we present a catechol chemistry-mediated core-shell nanoplatform for ROS scavenging-mediated oxidative stress alleviation and siRNA-mediated gene interference in a dextran sulfate sodium (DSS)-induced colitis model. The nanoplatform is constructed by employing mesoporous polydopamine nanoparticles (MPDA NPs) with surface modification of amines as the porous core for TNF-α-siRNA loading (31 wt %) and exerts an antioxidant function, while PDA-induced biomineralization of the calcium phosphate (CaP) coating is used as the pH-sensitive protective shell to prevent siRNA from premature release. The CaP layer degraded under weakly acidic subcellular conditions (lysosomes); thus, the synergistic integration of catechol and cation moieties on the exposed surface of MPDA resulted in an efficient lysosomal escape. Subsequently, effective ROS scavenging caused by the electron-donating ability of MPDA and efficient knocking down (40.5%) of tumor necrosis factor-α (TNF-α) via sufficient cytosolic gene delivery resulted in a synergistic anti-inflammation therapeutic effect both in vitro and in vivo. This work establishes the first paradigm of synergistic therapy in IBD by ROS scavenging and gene interference.

Self-Assembling Peptide-Based Hydrogels for Wound Tissue Repair

Wound healing is a long-term, multistage biological process that includes hemostasis, inflammation, proliferation, and tissue remodeling and requires intelligent designs to provide comprehensive and convenient treatment. The complexity of wounds has led to a lack of adequate wound treatment materials, which must systematically regulate unique wound microenvironments. Hydrogels have significant advantages in wound treatment due to their ability to provide spatiotemporal control over the wound healing process. Self-assembling peptide-based hydrogels are particularly attractive due to their innate biocompatibility and biodegradability along with additional advantages including ligand-receptor recognition, stimulus-responsive self-assembly, and the ability to mimic the extracellular matrix. The ability of peptide-based materials to self-assemble in response to the physiological environment, resulting in functionalized microscopic structures, makes them conducive to wound treatment. This review introduces several self-assembling peptide-based systems with various advantages and emphasizes recent advances in self-assembling peptide-based hydrogels that allow for precise control during different stages of wound healing. Moreover, the development of multifunctional self-assembling peptide-based hydrogels that can regulate and remodel the wound immune microenvironment in wound therapy with spatiotemporal control has also been summarized. Overall, this review sheds light on the future clinical and practical applications of self-assembling peptide-based hydrogels.

Nanostructures for drug delivery in respiratory diseases therapeutics: Revision of current trends and its comparative analysis

Respiratory diseases are leading causes of death and disability in developing and developed countries. The burden of acute and chronic respiratory diseases has been rising throughout the world and represents a major problem in the public health system. Acute respiratory diseases include pneumonia, influenza, SARS-CoV-2 and MERS viral infections; while chronic obstructive pulmonary disease (COPD), asthma and, occupational lung diseases (asbestosis, pneumoconiosis) and other parenchymal lung diseases namely lung cancer and tuberculosis are examples of chronic respiratory diseases. Importantly, chronic respiratory diseases are not curable and treatments for acute pathologies are particularly challenging. For that reason, the integration of nanotechnology to existing drugs or for the development of new treatments potentially benefits the therapeutic goals by making drugs more effective and exhibit fewer undesirable side effects to treat these conditions. Moreover, the integration of different nanostructures enables improvement of drug bioavailability, transport and delivery compared to stand-alone drugs in traditional respiratory therapy. Notably, there has been great progress in translating nanotechnology-based cancer therapies and diagnostics into the clinic; however, researchers in recent years have focused on the application of nanostructures in other relevant pulmonary diseases as revealed in our database search. Furthermore, polymeric nanoparticles and micelles are the most studied nanostructures in a wide range of diseases; however, liposomal nanostructures are recognized to be some of the most successful commercial drug delivery systems. In conclusion, this review presents an overview of the recent and relevant research in drug delivery systems for the treatment of different pulmonary diseases and outlines the trends, limitations, importance and application of nanomedicine technology in treatment and diagnosis and future work in this field.

Skin cancer biology and barriers to treatment: Recent applications of polymeric micro/nanostructures

Background

Skin cancer has been the leading type of cancer worldwide. Melanoma and non-melanoma skin cancers are now the most common types of skin cancer that have been reached to epidemic proportion. Based on the rapid prevalence of skin cancers, and lack of efficient drug delivery systems, it is essential to surge the possible ways to prevent or cure the disease.

Aim of review

Although surgical modalities and therapies have been made great progress in recent years, however, there is still an urgent need to alleviate its increased burden. Hence, understanding the precise pathophysiological signaling mechanisms and all other factors of such skin insults will be beneficial for the development of more efficient therapies.

Key scientific concepts of review

In this review, we explained new understandings about onset and development of skin cancer and described its management via polymeric micro/nano carriers-based therapies, highlighting the current key bottlenecks and future prospective in this field. In therapeutic drug/gene delivery approaches, polymeric carriers-based system is the most promising strategy. This review discusses that how polymers have successfully been exploited for development of micro/nanosized systems for efficient delivery of anticancer genes and drugs overcoming all the barriers and limitations associated with available conventional therapies. In addition to drug/gene delivery, intelligent polymeric nanocarriers platforms have also been established for combination anticancer therapies including photodynamic and photothermal, and for theranostic applications. This portfolio of latest approaches could promote the blooming growth of research and their clinical availability.

Microemulsion Based Nanostructures for Drug Delivery

Most of the active pharmaceutical compounds are often prone to display low bioavailability and biological degradation represents an important drawback. Due to the above, the development of a drug delivery system (DDS) that enables the introduction of a pharmaceutical compound through the body to achieve a therapeutic effect in a controlled manner is an expanding application. Henceforth, new strategies have been developed to control several parameters considered essential for enhancing delivery of drugs. Nanostructure synthesis by microemulsions (ME) consist of enclosing a substance within a wall material at the nanoscale level, allowing to control the size and surface area of the resulting particle. This nanotechnology has shown the importance on targeted drug delivery to improve their stability by protecting a bioactive compound from an adverse environment, enhanced bioavailability as well as controlled release. Thus, a lower dose administration could be achieved by minimizing systemic side effects and decreasing toxicity. This review will focus on describing the different biocompatible nanostructures synthesized by ME as controlled DDS for therapeutic purposes.

Effect of the disulfide bond and polyethylene glycol on the degradation and biophysicochemical properties of polyurethane micelles

The disulfide bond has emerged as a promising redox-sensitive switch for smart polymeric micelles, due to its properties of rapid response to the reductive environment and spatiotemporally-controlled therapeutic agent delivery. However, the dilemma of multifunctional nanomedicine is that the more intelligent the functionalities integrated into a system, the vaguer the understanding of the structure and interaction between the multi-functional moieties becomes. To better understand the interaction between the disulfide bond and methoxy polyethylene glycol (mPEG), and their effects on the biophysicochemical characterization of micelles, we developed a series of polyurethane micelles containing various densities of disulfide bonds and bearing different molecular weights of mPEG. In this work, we found that the critical factor determining the degradation rate of polymer micelles was the hydrophobic/hydrophilic ratio of broken polymer segments triggered by disulfide bond breaking. The higher density of the disulfide bond and longer mPEG chain accelerate the degradation process due to the disproportionate hydrophobic/hydrophilic ratio of the broken chain, which is the key factor to determine the micellization and stabilization of polymer micelles. This work provides a fundamental understanding of the interaction between the complex functional groups and a new insight into the mechanism of the micelle degradation process, offering guidance on the rational design and fabrication of multifunctional nanoformulations.

Recent advances in inhibiting atherosclerosis and restenosis: from pathogenic factors, therapeutic agents to nano-delivery strategies

Due to dominant atherosclerosis etiology, cardiovascular diseases (CVDs) remain the leading cause of morbidity and mortality worldwide. In clinical trials, advanced atherosclerotic plaques can be removed by angioplasty and vascular...

Tumor acidity-responsive polymeric nanoparticles to promote intracellular delivery of zoledronic acid by PEG detachment and positive charge exposure for enhanced antitumor potency

Zoledronic acid (ZA), a third-generation bisphosphonate, has been extensively used to treat osteoporosis and cancer bone metastasis and demonstrated to suppress proliferation of varied cancer cells and selectively kill tumor-associated...

Stimuli-responsive nanomaterials for cancer treatment: boundaries, opportunities and applications

Small molecule drugs, including most chemotherapies, are rapidly degraded and/or eliminated from the body, which is why high doses of these drugs are necessary, potentially producing toxic effects. Several types of nanoparticles loaded with anti-cancer drugs have been designed to overcome the disadvantages of conventional therapies. Modified nanoparticles can circulate for a long time, thus improving the solubility and biodistribution of drugs. Furthermore, they also allow the controlled release of the payload once its target tissue has been reached. These mechanisms can reduce the exposure of healthy tissues to chemotherapeutics, since the drugs are only released in the presence of specific tumour stimuli. Overall, these properties can improve the effectiveness of treatments while reducing undesirable side effects. In this article, we review the recent advances in stimuli-responsive albumin, gold and magnetic nanostructures for controlled anti-cancer drug delivery. These nanostructures were designed to release drugs in response to different internal and external stimuli of the cellular environment, including pH, redox, light and magnetic fields. We also describe various examples of applications of these nanomaterials. Overall, we shed light on the properties, potential clinical translation and limitations of stimuli-responsive nanoparticles for cancer treatment.

Emerging Nano-Based Strategies Against Drug Resistance in Tumor Chemotherapy

Drug resistance is the most significant causes of cancer chemotherapy failure. Various mechanisms of drug resistance include tumor heterogeneity, tumor microenvironment, changes at cellular levels, genetic factors, and other mechanisms. In recent years, more attention has been paid to tumor resistance mechanisms and countermeasures. Nanomedicine is an emerging treatment platform, focusing on alternative drug delivery and improved therapeutic effectiveness while reducing side effects on normal tissues. Here, we reviewed the principal forms of drug resistance and the new possibilities that nanomaterials offer for overcoming these therapeutic barriers. Novel nanomaterials based on tumor types are an excellent modality to equalize drug resistance that enables gain more rational and flexible drug selectivity for individual patient treatment. With the emergence of advanced designs and alternative drug delivery strategies with different nanomaterials, overcome of multidrug resistance shows promising and opens new horizons for cancer therapy. This review discussed different mechanisms of drug resistance and recent advances in nanotechnology-based therapeutic strategies to improve the sensitivity and effectiveness of chemotherapeutic drugs, aiming to show the advantages of nanomaterials in overcoming of drug resistance for tumor chemotherapy, which could accelerate the development of personalized medicine.

Dynamic self-assembly of mannosylated-calix[4]arene into micelles for the delivery of hydrophobic drugs

Carbohydrate-lectin interactions and glycol-molecule-driven self-assembly are powerful yet challenging strategies to create supramolecular nanostructures for biomedical applications. Herein, we develop a modular approach of micellization with a small molecular mannosylated-calix[4]arene synthetic core, CA₄-Man3, to generate nano-micelles, CA₄-Man3-NPs, which can target cancer cell surface receptors and facilitate the delivery of hydrophobic cargo. The oligomeric nature of the calix[4]arene enables the dynamic self-assembly of calix[4]arene (CA₄), where an amphiphile, functionalized with mannose units (CA-glycoconjugates) in the upper rim and alkylated lower rim, afforded the CA₄-Man3-NPs in a controllable manner. The presence of thiourea units between calixarene and tri-mannose moiety facilitated the formation of a stable core with bidentate hydrogen bonds, which in turn promoted mannose receptor targeted uptake and helped in the intracellular pH-responsive release of antineoplastic doxorubicin (Dox). Physiochemical features including the stability of the nanomicelle could circumvent the undesirable leakage of the cargoes, ensuring maximum therapeutic output with minimum off-targeted toxicity. Most importantly, surface-enhanced Raman scattering (SERS) was utilized for the first time to evaluate the critical micelle concentration during the formation, cellular uptake and intracellular drug release. The present study not only provides an architectural design of a new class of organic small molecular nanomicelles but also unveils a robust self-assembly approach that paves the way for the delivery of a wide range of hydrophobic chemotherapeutic drugs.

Multi-functional polymeric micelles for chemotherapy-based combined cancer therapy

Currently, the therapeutic performance of traditional mono-chemotherapy on cancers remains unsatisfactory because of the tumor heterogeneity and multidrug resistance. In light of intricate tumor structures and distinct tumor microenvironments (TMEs), combinational therapeutic strategies with multiple anticancer drugs from different mechanisms can synergistically optimize the outcomes and concomitantly minimize the adverse effects during the therapy process. Extensive research on polymeric micelles (PMs) for biomedical applications has revealed the growing importance of nanomedicines for cancer therapy in the recent decade. Starting from traditional simple delivery systems, PMs have been extended to multi-faceted therapeutic strategies. Here we review and summarize the most recent advances in combinational therapy based on multifunctional PMs including a combination of multiple anticancer drugs, chemo-gene therapy, chemo-phototherapy and chemo-immunotherapy. The design approaches, action mechanisms and therapeutic applications of these nanodrugs are summarized. In addition, we highlight the opportunities and potential challenges associated with this promising field, which will provide new guidelines for advanced combinational cancer chemotherapy.

Construction of a Drug Delivery System via pH-Responsive Polymeric Nanomicelles Containing Ferrocene for DOX Release and Enhancement of Therapeutic Effects

We report an amphiphilic block copolymer via poly(ethylene glycol) methyl ether-D_labile-poly(caprolactone)-ferrocene (mPEG-D_labile-PCL-Fc) to deliver anticancer drug doxorubicin (DOX). Lipase Novozyme-435 was used as a catalyst for ring-opening polymerization with ε-caprolactone, and an acid-sensitive Schiff base was used to connect the hydrophilic and hydrophobic parts; the ferrocene provided ferrous ions and was introduced at the end of the amphiphilic copolymer. The resulting copolymers were characterized by ¹H NMR/¹³C NMR and could be self-assembled in an aqueous solution to form nanomicelles with PCL-Fc as a hydrophobic core and mPEG as a hydrophilic shell. Transmission electron microscopy showed that the micelles were spherical and nanosized before and after DOX loading. The blank micelles also showed good biocompatibility. The drug-loaded polymeric nanomicelles exhibited a positive anticancer effect relative to the copolymers without ferrocene; the therapeutic effect of drug-loaded micelles containing ferrocene was more obvious. In vitro drug release results also showed that the polymer had a good pH response. Confocal microscopy also showed that polymeric micelles can effectively deliver and release the drug; the polymer containing ferrocene also leads to significantly improved ROS levels in tumor cells. Ferrocene can effectively and synergistically inhibit tumor cells with DOX.

Recent advances in polymeric core-shell nanocarriers for targeted delivery of chemotherapeutic drugs

The treatment effect of chemotherapeutics is often impeded by nonspecific biodistribution and limited biocompatibility. Polymeric core-shell nanocarriers (PCS NCs) composed of a polymer core and at least one shell have been widely applied for cancer therapy and have shown great potential in selectively delivering chemotherapeutic drugs to tumor sites. These PCS NCs can effectively ameliorate the delivery efficiency and therapeutic index of anticarcinogens by prolonging drug residence in the bloodstream, enhancing tumor tissue drug penetration, facilitating cellular drug uptake, controlling the spatiotemporal release of payloads, or codelivering two or more bioactive agents. This review summarizes recently published literature on using PCS NCs to transport chemotherapeutic drugs with poor aqueous solubility and discusses their design principles, structural features, functional properties, and potential limitations.

pH-Sensitive PEGylated Liposomal Silybin: Synthesis, In Vitro and In Vivo Anti-Tumor Evaluation

The drug delivery systems improve the efficacy of chemotherapeutics through enhanced targeting and controlled release however, biological barriers of tumor microenvironment greatly impede the penetration of nanomedicine within the tumor. We report herein the fabrication of a PEG-detachable silybin (SLB) pH-sensitive liposome decorated with TAT-peptide. For this, Acyl hydrazide-activated PEG₂₀₀₀ was prepared and linked with ketone-derivatized DPPE via an acid-labile hydrazone bond to form mPEG₂₀₀₀-HZ-DPPE. TAT peptide was conjugated with a shorter -PEG₁₀₀₀-DSPE spacer and post-inserted into PEGylated liposome (DPPC: mPEG₂₀₀₀-DSPE: Chol). To prepare nanoliposomes (around 100 nm), first, a novel method was used to prepare SLB-Soya PC (SLB-SPC) complex, then this complex was incorporated into nanoliposomes. The pH-sensitivity and shielding effect of long PEG chain on TAT peptide was investigated using DiI liposome and FACS analysis. Pre-treatment to the lowered pH enhanced cellular association of TAT-modified pH-sensitive liposome due to the cleavage of hydrazone bond and TAT exposure. Besides, TAT-modified pH-sensitive liposomes significantly reduced cell viability compared to the plain liposome. In vivo results were very promising with pH-sensitive liposome by detaching PEG moieties upon exposure to the acidic tumor microenvironment, enhancing cellular uptake, retarding tumor growth, and prolonging the survival of 4T1 breast tumor-bearing BALB/c mice. TAT modification of pH-sensitive liposome improved cancer cell association and cytotoxicity and demonstrated potential intracellular delivery upon exposure to acidic pH. However, in in vivo studies, TAT as a targeting ligand significantly decreased the therapeutic efficacy of the formulation attributed to an inefficient tumor accumulation and higher release rate in the circulation. The results of this study indicated that pH-sensitive liposome containing SLB, which was prepared with a novel method with a significant SLB loading efficiency, is very effective in the treatment of 4T1 breast tumor-bearing BALB/c mice and merits further investigation.

Oxygen-Based Nanocarriers to Modulate Tumor Hypoxia for Ameliorated Anti-Tumor Therapy: Fabrications, Properties, and Future Directions

Over the past five years, oxygen-based nanocarriers (NCs) to boost anti-tumor therapy attracted tremendous attention from basic research and clinical practice. Indeed, tumor hypoxia, caused by elevated proliferative activity and dysfunctional vasculature, is directly responsible for the less effectiveness or ineffective of many conventional therapeutic modalities. Undeniably, oxygen-generating NCs and oxygen-carrying NCs can increase oxygen concentration in the hypoxic area of tumors and have also been shown to have the ability to decrease the expression of drug efflux pumps (e.g., P-gp); to increase uptake by tumor cells; to facilitate the generation of cytotoxic reactive oxide species (ROS); and to evoke systematic anti-tumor immune responses. However, there are still many challenges and limitations that need to be further improved. In this review, we first discussed the mechanisms of tumor hypoxia and how it severely restricts the therapeutic efficacy of clinical treatments. Then an up-to-date account of recent progress in the fabrications of oxygen-generating NCs and oxygen-carrying NCs are systematically introduced. The improved physicochemical and surface properties of hypoxia alleviating NCs for increasing the targeting ability to hypoxic cells are also elaborated with special attention to the latest nano-technologies. Finally, the future directions of these NCs, especially towards clinical translation, are proposed. Therefore, we expect to provide some valued enlightenments and proposals in engineering more effective oxygen-based NCs in this promising field in this comprehensive overview.

A review of stimuli-responsive polymeric micelles for tumor-targeted delivery of curcumin

Despite a potential drug with multiple pharmacological activities, curcumin has disadvantages of the poor water solubility, rapid metabolism, low bioavailability, which considerably limit its clinical application. Currently, polymeric micelles (PMs) have gained widespread concern due to their advantageous physical and chemical properties, easy preparation, and biocompatibility. They can be used to improve drug solubility, prolong blood circulation time, and allow passive targeted drug delivery to tumor through enhanced penetration and retention effect. Moreover, studies focused on tumor microenvironment offer alternatives to design stimulus-responsive smart PMs based on low pH, high levels of glutathione, altered enzyme expression, increased reactive oxygen species production, and hypoxia. There are various external stimuli, such as light, ultrasound, and temperature. These endogenous/exogenous stimuli can be used for the research of intelligent micelles. Intelligent PMs can effectively load curcumin with improved solubility, and intelligently respond to release the drug at a controlled rate at targeted sites such as tumors to avoid early release, which markedly improves the bioavailability of curcumin. The present review is aimed to discuss and summarize recent developments in research of curcumin-loaded intelligent PMs based on endogenous and exogenous stimuli, and facilitates the development of novel delivery systems for future research.

Functionalized Particles Designed for Targeted Delivery

Pure bioactive compounds alone can only be exceptionally administered in medical treatment. Usually, drugs are produced as various forms of active compounds and auxiliary substances, combinations assuring the desired healing functions. One of the important drug forms is represented by a combination of active substances and particle-shaped polymer in the nano- or micrometer size range. The review describes recent progress in this field balanced with basic information. After a brief introduction, the paper presents a concise overview of polymers used as components of nano- and microparticle drug carriers. Thereafter, progress in direct synthesis of polymer particles with functional groups is discussed. A section is devoted to formation of particles by self-assembly of homo- and copolymer-bearing functional groups. Special attention is focused on modification of the primary functional groups introduced during particle preparation, including introduction of ligands promoting anchorage of particles onto the chosen living cell types by interactions with specific receptors present in cell membranes. Particular attention is focused on progress in methods suitable for preparation of particles loaded with bioactive substances. The review ends with a brief discussion of the still not answered questions and unsolved problems.

Novel multi-stimuli responsive functionalized PEG-based co-delivery nanovehicles toward sustainable treatments of multidrug resistant tumor

The efficacy of ongoing anticancer treatment is often compromised by some barriers, such as low drug content, nonspecific release of drug delivery system, and multidrug resistance (MDR) effect of tumors. Herein, in the research a novel functionalized PEG-based polymer cystine-(polyethylene glycol)2-b-(poly(2-methacryloyloxyethyl ferrocenecarboxylate)2) (Cys-(PEG45)2-b-(PMAOEFC)2) with multi-stimuli sensitive mechanism was constructed, in which doxorubicin (DOX) was chemical bonded through Schiff base structure to provide acid labile DOX prodrug (DOX)2-Cys-(PEG45)2-b-(PMAOEFC)2. Afterwards, paclitaxel (PTX) and its diselenide bond linked PTX dimer were encapsulated into the prodrug through physical loading, to achieve pH and triple redox responsive (DOX)2-Cys-(PEG45)2-b-(PMAOEFC)2@PTX and (DOX)2-Cys-(PEG45)2-b-(PMAOEFC)2@PTX dimer with ultrahigh drugs content. The obtained nanovehicles could self-assemble into globular micelles with good stability based on fluorescence spectra and TEM observation. Moreover, there was a remarkable "reassembly-disassembly" behavior caused by phase transition of micelles under the mimic cancerous physiological environment. DOX and PTX could be on-demand released in acid and redox stress mode, respectively. Meanwhile, in vivo anticancer studies revealed the significant tumor inhibition of nanoformulas. This work offered facile strategies to fabricate drug nanaovehicles with tunable drug content and types, it has a profound significance in overcoming MDR effect, which provided more options for sustainable cancer treatment according to the desired drug dosage and the stage of tumor growth.

A Smart Multifunctional Nanoparticle for Enhanced Near-Infrared Image-Guided Photothermal Therapy Against Gastric Cancer

BACKGROUND

Surgery is considered to be a potentially curative approach for gastric cancer. However, most cases are diagnosed at a very advanced stage for the lack of typical symptoms in the initial stage, which makes it difficult to completely surgical resect of tumors. Early diagnosis and precise personalized intervention are urgent issues to be solved for improving the prognosis of gastric cancer. Herein, we developed an RGD-modified ROS-responsive multifunctional nanosystem for near-infrared (NIR) imaging and photothermal therapy (PTT) against gastric cancer.

METHODS

Firstly, the amphiphilic polymer was synthesized by bromination reaction and nucleophilic substitution reaction of carboxymethyl chitosan (CMCh) and 4-hydroxymethyl-pinacol phenylborate (BAPE). Then, it was used to encapsulate indocyanine green (ICG) and modified with RGD to form a smart multifunctional nanoparticle targeted to gastric cancer (CMCh-BAPE-RGD@ICG). The characteristics were determined, and the targeting capacity and biosafety were evaluated both in vitro and in vivo. Furthermore, CMCh-BAPE-RGD@ICG mediated photothermal therapy (PTT) effect was studied using gastric cancer cells (SGC7901) and SGC7901 tumor model.

RESULTS

The nanoparticle exhibited suitable size (≈ 120 nm), improved aqueous stability, ROS-responsive drug release, excellent photothermal conversion efficiency, enhanced cellular uptake, and targeting capacity to tumors. Remarkably, in vivo studies suggested that CMCh-BAPE-RGD@ICG could accurately illustrate the location and margin of the SGC7901 tumor through NIR imaging in comparison with non-targeted nanoparticles. Moreover, the antitumor activity of CMCh-BAPE-RGD@ICG-mediated PTT could effectively suppress tumor growth by inducing necrosis and apoptosis in cancer cells. Additionally, CMCh-BAPE-RGD@ICG demonstrated excellent biosafety both in vitro and in vivo.

CONCLUSION

Overall, our study provides a biocompatible theranostic nanoparticle with enhanced tumor-targeting ability and accumulation to realize NIR image-guided PTT in gastric cancer.

Brain-Targeted Dual Site-Selective Functionalized Poly(β-Amino Esters) Delivery Platform for Nerve Regeneration

Brain injuries are devastating central nervous system diseases, resulting in cognitive, motor, and sensory dysfunctions. However, clinical therapeutic options are still limited for brain injuries, indicating an urgent need to investigate new therapies. Furthermore, the efficient delivery of therapeutics across the blood-brain barrier (BBB) to the brain is a serious problem. In this study, a facile strategy of dual site-selective functionalized (DSSF) poly(β-amino esters) was developed using bio-orthogonal chemistry for promoting brain nerve regeneration. Fluorescence colocalization studies demonstrated that these proton-sponge DSSF poly(β-amino esters) targeted mitochondria through electrostatic interactions. More importantly, this delivery system could effectively accumulate in the injured brain sites and accelerate the recovery of the injured brain. Finally, this DSSF poly(β-amino esters) platform may provide a new methodology for the construction of dual regioselective carriers in protein/peptide delivery and tissue engineering.

A cyanine-based polymeric nanoplatform with microenvironment-driven cascaded responsiveness for imaging-guided chemo-photothermal combination anticancer therapy

Finding out how to overcome multistage biological barriers for nanocarriers in cancer therapy to obtain highly precise drug delivery is still a challenge. Herein, we prepared a multistage and cascaded switchable polymeric nanovehicle, self-assembled from polyethylene glycol grafted amphiphilic copolymer containing hydrophobic poly(ortho ester) and hydrophilic ethylenediamine-modified poly(glycidyl methacrylate) (PEG-g-p(GEDA-co-DMDEA)) for imaging-guided chemo-photothermal combination anticancer therapy. Notably, a novel ATRP initiator containing cyanine dye was designed and attached to the polymer, providing the nanovehicle with NIR-light induced photothermal and fluorescent properties. The PEG shell displayed tumor-microenvironment-induced detachment, resulting in the surface charge change of the nanovehicle from neutral to positive and thus enhancing cellular uptake. Subsequently, the hydrophobic pDMDEA hydrolyzed into a hydrophilic segment in the acidic lysosome, leading to sufficient drug release. Finally, with the aid of the photothermal property, the therapeutic drug DOX successfully escaped from the lysosome to exert chemotherapy. This well-defined polymeric nanoplatform promoted the development of designing novel theranostic polymeric nanovehicles for precise cancer therapy.

Recent advances in MoS2-based photothermal therapy for cancer and infectious disease treatment

Photothermal therapy (PTT) is a treatment combining laser irradiation and a photothermal transduction agent (PTA) to generate hyperthermia, which is used to efficiently and effectively treat cancer and prevent bacteria-induced infectious diseases. MoS2, an increasingly used two-dimensional transition metal dichalcogenide, which shows high absorbance in the near infrared (NIR) laser region, has been extensively utilized as a novel PTA in biomedical applications. The use of MoS2 as an advanced photoabsorbing agent has introduced a more efficient cancer therapy and improved antibacterial efficacy. In this review, we firstly summarize the recent advances in the MoS2-based platform for PTT in cancer and bacteria-induced infectious diseases treatments. We then discuss that the combination of MoS2-based PTT and other biomedical methods along with multimodality imaging, such as chemotherapy, photodynamic therapy (PDT) and immunotherapy, might be a promising strategy for cancer treatment. Furthermore, a new concept is proposed wherein MoS2-based PTT and combined therapies based on this could be more effective for the treatment of various bacteria-induced infectious diseases. Finally, research progress, challenges, and perspectives for the future development of this MoS2-based platform in cancer and bacteria-induced infectious disease treatments are discussed and concluded. Collectively, we think that MoS2-based PTT with high therapeutic efficacy and minimal side-effects could be potentially applied in clinical settings to improve cancer and infectious disease treatments.

Engineered bovine serum albumin-based nanoparticles with pH-sensitivity for doxorubicin delivery and controlled release

In this work, we prepared a stimuli-responsive system for drug delivery and controlled release by engineering the bovine serum albumin (BSA). The doxorubicin (DOX)-loaded BSA nanoparticles (NPs) were conveniently prepared using desolvation method, followed by crosslinking through Schiff base bonds, leading to pH-sensitive DOX-loaded system (DOXs@BSA NPs). The resulted DOXs@BSA NPs showed high drug loading capacity (21.4%), and the particle size was about 130 nm with narrow polydispersity and high negative surface charge (-20.5 mV). The pH-sensitivity of DOXs@BSA NPs was evidenced by the size changes and charge reversal after incubation at different pH values. The DOXs@BSA NPs showed high serum stability which indicated the prolonged circulation time. The in vitro drug release experiment showed that the release of DOX was obviously accelerated by acidity because of disassembly of NPs induced by cleavage of Schiff base bonds. The drug release mechanism was thoroughly studied using a semi-empirical model, further confirming the pH played an important role in drug controlled release process. The results of cytotoxicity assay revealed that DOXs@BSA NPs exhibited much higher toxic effects for tumor cells in comparison to the free DOX control. Collectively, these results demonstrated that DOXs@BSA NPs might be potential application for drug delivery and controlled release in cancer chemotherapy. Moreover, this work also showed that preparation of stimuli-responsive drug delivery system by engineering the commercial biomaterials could be a promising method to develop multi-functional nanomedicine.

Polymeric Drug Delivery Systems Bearing Cholesterol Moieties: A Review

This review aims to provide an overview of polymers comprising cholesterol moiety/ies designed to be used in drug delivery. Over the last two decades, there have been many papers published in this field, which are summarized in this review. The primary focus of this article is on the methods of synthesis of polymers bearing cholesterol in the main chain or as side chains. The data related to the composition, molecular weight, and molecular weight distribution of polymers are presented. Moreover, other aspects, such as forms of carriers, types of encapsulated drugs, encapsulation efficiency and capacity, are also included.

Effect of temperature and pH on the encapsulation and release of β-carotene from octenylsuccinated oat β-glucan micelles

Effect and working mechanism of temperature and pH on encapsulation and release of β-carotene from octenylsuccinated-oat-β-glucan-micelles (OSβG-Ms) were investigated. The stability and solubility of β-carotene, and changes in surface hydrophilicity, core hydrophobicity, and size of β-carotene-loaded-OSβG-Ms were determined. When exposed to temperature (25-45 °C) and pH (4.5-8.5), β-carotene solubilization changed in parabolic manners. Size and absolute zeta-potential of β-carotene-loaded-OSβG-Ms decreased with temperature, while they gave parabolic changing patterns with pH. Those results were ascribed to their hydrophilicity, hydrophobicity, and core/shell compactness via regulating molecule mobility, orientation, and interactions by temperature/pH. The higher temperature concluded with higher β-carotene release, while a U-shaped release profile was observed with pH. Besides its diffusion, erosion-induced shrinking and collapsing of OSβG-Ms favored β-carotene release at pH 1.2-4.5, which was replaced by swelling-induced structural-relaxation at pH 6.8-8.5. The results were favourable in controlling the behavior of β-carotene-loaded-OSβG-Ms by selectively applying environmental parameters.

Targeting Fluorescence Imaging of RGD-Modified Indocyanine Green Micelles on Gastric Cancer

Early diagnosis and complete resection of the tumor is an important way to improve the quality of life of patients with gastric cancer. In recent years, near-infrared (NIR) materials show great potential in fluorescence-based imaging of the tumors. To realize a satisfying intraoperative fluorescence tumor imaging, there are two pre-requirements. One is to obtain a stable agent with a relatively longer circulation time. The second is to make it good biocompatible and specific targeting to the tumor. Here, we developed an RGD-modified Distearyl acylphosphatidyl ethanolamine-polyethylene glycol micelle (DSPE-PEG-RGD) to encapsulate indocyanine green (ICG) for targeting fluorescence imaging of gastric cancer, aimed at realizing tumor-targeted accumulation and NIR imaging. ¹H NMR spectroscopy confirmed its molecular structure. The characteristics and stability results indicated that the DSPE-PEG-RGD@ICG had a relatively uniform size of <200 nm and longer-term fluorescence stability. RGD peptides had a high affinity to integrin α_vβ₃ and the specific targeting effect on SGC7901 was assessed by confocal microscopy in vitro. Additionally, the results of cytotoxicity and blood compatibility in vitro were consistent with the acute toxicity test in vivo, which revealed good biocompatibility. The biodistribution and tumor targeting image of DSPE-PEG-RGD@ICG were observed by an imaging system in tumor-bearing mice. DSPE-PEG-RGD@ICG demonstrated an improved accumulation in tumors and longer circulation time when compared with free ICG or DSPE-PEG@ICG. In all, DSPE-PEG-RGD@ICG demonstrated ideal properties for tumor target imaging, thus, providing a promising way for the detection and accurate resection of gastric cancer.