Design of a cellular-uptake-shielding "plug and play" template for photo controllable drug release

Cell Membrane as A Promising Therapeutic Target: From Materials Design to Biomedical Applications

The cell membrane is a crucial component of cells, protecting their integrity and stability while facilitating signal transduction and information exchange. Therefore, disrupting its structure or impairing its functions can potentially cause irreversible cell damage. Presently, the tumor cell membrane is recognized as a promising therapeutic target for various treatment methods. Given the extensive research focused on cell membranes, it is both necessary and timely to discuss these developments, from materials design to specific biomedical applications. This review covers treatments based on functional materials targeting the cell membrane, ranging from well-known membrane-anchoring photodynamic therapy to recent lysosome-targeting chimaeras for protein degradation. The diverse therapeutic mechanisms are introduced in the following sections: membrane-anchoring phototherapy, self-assembly on the membrane, in situ biosynthesis on the membrane, and degradation of cell membrane proteins by chimeras. In each section, we outline the conceptual design or general structure derived from numerous studies, emphasizing representative examples to understand advancements and draw inspiration. Finally, we discuss some challenges and future directions in membrane-targeted therapy from our perspective. This review aims to engage multidisciplinary readers and encourage researchers in related fields to advance the fundamental theories and practical applications of membrane-targeting therapeutic agents.

Cyclodextrin-Based Polymeric Drug Delivery Systems for Cancer Therapy

Cyclodextrins (CDs) are one of the most extensively studied cyclic-oligosaccharides due to their low toxicity, good biodegradability and biocompatibility, facile chemical modification, and unique inclusion capacity. However, problems such as poor pharmacokinetics, plasma membrane disruption, hemolytic effects and a lack of target specificity still exist for their applications as drug carriers. Recently, polymers have been introduced into CDs to combine the advantages of both biomaterials for the superior delivery of anticancer agents in cancer treatment. In this review, we summarize four types of CD-based polymeric carriers for the delivery of chemotherapeutics or gene agents for cancer therapy. These CD-based polymers were classified based on their structural properties. Most of the CD-based polymers were amphiphilic with the introduction of hydrophobic/hydrophilic segments and were able to form nanoassemblies. Anticancer drugs could be included in the cavity of CDs, encapsulated in the nanoparticles or conjugated on the CD-based polymers. In addition, the unique structures of CDs enable the functionalization of targeting agents and stimuli-responsive materials to realize the targeting and precise release of anticancer agents. In summary, CD-based polymers are attractive carriers for anticancer agents.

A pH-Responsive Charge-Convertible Drug Delivery Nanocarrier for Precise Starvation and Chemo Synergistic Oncotherapy

A pH-responsive charge-convertible drug delivery nanocarrier (MSN-TPZ-GOx@ZnO@PAH-PEG-DMMA, abbreviated as MTGZ@PPD) was prepared, which could specifically release hypoxia-activated chemotherapeutic Tirapazamine (TPZ) and glucose oxidase (GOx) in the tumor site for precise starvation and chemo synergistic oncotherapy. Acid-responsive Schiff base structure modified mesoporous silica nanoparticles (MSN) co-load with GOx and TPZ, then link with ZnO quantum dots (QDs). PAH-PEG-DMMA (PPD) polymer makes MTGZ@PPD with biocompatibility and charge-convertible feature. MTGZ@PPD is negatively charged at physiological pH, and the charge reversal of PPD and acidolysis of the Schiff base structure under the acidic tumor microenvironment (TME) induce a positively charged surface, which could potentiate the cell internalization. ZnO QDs could decompose at acidic TME, achieving controllable drug release. GOx could starve the tumor cells and enhance hypoxia level, thus initiates the activation of TPZ to realize synergistic starvation therapy and chemotherapy. This intelligent MTGZ@PPD has shown great potential for starvation and chemo synergistic oncotherapy.

Opportunities and Challenges of Switchable Materials for Pharmaceutical Use

Switchable polymeric materials, which can respond to triggering signals through changes in their properties, have become a major research focus for parenteral controlled delivery systems. They may enable externally induced drug release or delivery that is adaptive to in vivo stimuli. Despite the promise of new functionalities using switchable materials, several of these concepts may need to face challenges associated with clinical use. Accordingly, this review provides an overview of various types of switchable polymers responsive to different types of stimuli and addresses opportunities and challenges that may arise from their application in biomedicine.

Drug Delivery Systems with a “Tumor-Triggered” Targeting or Intracellular Drug Release Property Based on DePEGylation

Coating nanosized anticancer drug delivery systems (DDSs) with poly(ethylene glycol) (PEG), the so-called PEGylation, has been proven an effective method to enhance hydrophilicity, aqueous dispersivity, and stability of DDSs. What is more, as PEG has the lowest level of protein absorption of any known polymer, PEGylation can reduce the clearance of DDSs by the mononuclear phagocyte system (MPS) and prolong their blood circulation time in vivo. However, the “stealthy” characteristic of PEG also diminishes the uptake of DDSs by cancer cells, which may reduce drug utilization. Therefore, dynamic protection strategies have been widely researched in the past years. Coating DDSs with PEG through dynamic covalent or noncovalent bonds that are stable in blood and normal tissues, but can be broken in the tumor microenvironment (TME), can achieve a DePEGylation-based “tumor-triggered” targeting or intracellular drug release, which can effectively improve the utilization of drugs and reduce their side effects. In this review, the stimuli and methods of “tumor-triggered” targeting or intracellular drug release, based on DePEGylation, are summarized. Additionally, the targeting and intracellular controlled release behaviors of the DDSs are briefly introduced.

Photo-Based Nanomedicines Using Polymeric Systems in the Field of Cancer Imaging and Therapy

The use of photo-based nanomedicine in imaging and therapy has grown rapidly. The property of light in converting its energy into different forms has been exploited in the fields of optical imaging (OI) and phototherapy (PT) for diagnostic and therapeutic applications. The development of nanotechnology offers numerous advantages to overcome the challenges of OI and PT. Accordingly, in this review, we shed light on common photosensitive agents (PSAs) used in OI and PT; these include fluorescent and bioluminescent PSAs for OI or PT agents for photodynamic therapy (PDT) and photothermal therapy (PTT). We also describe photo-based nanotechnology systems that can be used in photo-based diagnostics and therapies by using various polymeric systems.

CXCL12/CXCR4 Axis-Targeted Dual-Functional Nano-Drug Delivery System Against Ovarian Cancer

Introduction

Traditional chemotherapy for ovarian cancer is limited due to drug resistance and systemic side effects. Although various targeted drug delivery strategies have been designed to enhance drug accumulation at the tumor site, simply improvement of targeting capability has not consistently led to satisfactory outcomes. Herein, AMD3100 was selected as the targeting ligand because of its high affinity to chemokine receptor 4 (CXCR4), which was highly expressed on ovarian cancer cells. Moreover, the AMD3100 has been proved having blockage capability of stromal cell-derived factor 1 (SDF-1 or CXCL12)/CXCR4 axis and to be a sensitizer of chemotherapeutic therapy. We designed a dual-functional targeting delivery system by modifying paclitaxel (PTX)-loaded PEGylation bovine serum albumin (BSA) nanoparticles (NPs) with AMD3100 (AMD-NP-PTX), which can not only achieve specific tumor-targeting efficiency but also enhance the therapeutic outcomes.

Methods

AMD3100 was chemically modified to Mal-PEG-NHS followed by reacting with BSA, then AMD-NP-PTX was synthesized and characterized. The targeting efficiency of AMD-NP was evaluated both in vitro and in vivo. The anticancer effect of AMD-NP-PTX was determined on Caov3 cells and ovarian cancer-bearing nude mice. Finally, the potential therapeutic mechanism was studied.

Results

AMD-NP-PTX was synthesized successfully and well characterized. Cellular uptake assay and in vivo imaging experiments demonstrated that NPs could be internalized by Caov3 cells more efficiently after modification of AMD3100. Furthermore, the AMD-NP-PTX exhibited significantly enhanced inhibition effect on tumor growth and metastasis compared with PTX, NP-PTX and free AMD3100 plus NP-PTX both in vitro and in vivo, and demonstrated improved safety profile. We also confirmed that AMD-NP-PTX worked through targeting CXCL12/CXCR4 axis, thereby disturbing its downstream signaling pathways including epithelial–mesenchymal transition (EMT) processes and nuclear factor κB (NF-κB) pathway.

Conclusion

The AMD-NP-PTX we designed would open a new avenue for dual-functional NPs in ovarian cancer therapy.

Pipette-like action of a reusable and NIR light-responsive film for the aspiration and removal of viable cancer cells

A reusable and NIR light-responsive composite membrane is developed to capture/release viable cancer cells.

Visible light-triggered gel-to-sol transition in halogen-bond-based supramolecules

Photoresponsive supramolecular gels have aroused continuous attention because of their extensive applications; however, most studies utilize UV light, which inevitably brings about some health and environmental issues. The halogen bond is an important driving force for constructing supramolecules due to its high directionality, tunable strength, good hydrophobicity, and large size of the halogen atoms. Yet, it still remains a formidable challenge to utilize halogen bonds as a driving force to fabricate a visible light responsive gel. In this work, to fabricate such a gel, azopyridine-containing Azopy-C_n (n = 8, 10, 12) was selected as a halogen bond acceptor, while 1,2-bis(2,3,5,6-tetrafluoro-4-iodophenyl)diazene (BTFIPD) was chosen as both the halogen bond donor and visible light responsive moiety. The visible light response of BTFIPD resulted from the significant separation of n-π* energy levels between trans and cis isomers due to the introduction of an electron-withdrawing group (fluorine) to azobenzene at the ortho-position. Interestingly, the gel exhibited a good gel-to-sol transition behavior upon green light irradiation. At the same time, the morphologies varied from uniform narrow flakes to broad sheets with increasing illumination time. We provide an environmentally-friendly visible light-triggered method to regulate the phase transition of supramolecular materials in applications ranging from energy conversion to information storage.

The advanced role of carbon quantum dots in nanomedical applications

Carbon quantum dots (CQDs) have emerged as a potential material in the diverse fields of biomedical applications due to their numerous advantageous properties including fluorescence, water solubility, biocompatibility, low toxicity, small size and ease of modification, inexpensive scale-up production, and versatile conjugation with other nanoparticles. Thus, CQDs became a preferable choice in various biomedical applications such as nanocarriers for drugs, therapeutic genes, photosensitizers, and antibacterial molecules. Further, their potentials have also been verified in multifunctional diagnostic platforms, cellular and bacterial bio-imaging, development of theranostics nanomedicine, etc. This review provides a concise insight into the progress and evolution in the field of CQD research with respect to methods/materials available in bio-imaging, theranostics, cancer/gene therapy, diagnostics, etc. Further, our discussion is extended to explore the role of CQDs in nanomedicine which is considered to be the future of biomedicine. This study will thus help biomedical researchers in tapping the potential of CQDs to overcome various existing technological challenges.

Recent Advances in Subcellular Targeted Cancer Therapy Based on Functional Materials

Recently, diverse functional materials that take subcellular structures as therapeutic targets are playing increasingly important roles in cancer therapy. Here, particular emphasis is placed on four kinds of therapies, including chemotherapy, gene therapy, photodynamic therapy (PDT), and hyperthermal therapy, which are the most widely used approaches for killing cancer cells by the specific destruction of subcellular organelles. Moreover, some non-drug-loaded nanoformulations (i.e., metal nanoparticles and molecular self-assemblies) with a fatal effect on cells by influencing the subcellular functions without the use of any drug molecules are also included. According to the basic principles and unique performances of each treatment, appropriate strategies are developed to meet task-specific applications by integrating specific materials, ligands, as well as methods. In addition, the combination of two or more therapies based on multifunctional nanostructures, which either directly target specific subcellular organelles or release organelle-targeted therapeutics, is also introduced with the intent of superadditive therapeutic effects. Finally, the related challenges of critical re-evaluation of this emerging field are presented.

Formulation Optimization and Biopharmaceutical Evaluation of Imatinib Mesylate Loaded β-cyclodextrin Nanosponges

BACKGROUND

Many researchers have prepared and evaluated nanosponges and claimed their advantages as an effective drug carrier, especially it was observed prominently in case of anti-fungal drugs. The materials employed to synthesize nanosponges were mainly crosslinking agents, different beta-cyclodextrin and other cellulose-based polymers. Many of them had used ratio proportions of cross-linking agents, d polymers to synthesize these nanosponges which ultimately produce a porous mesh-like network known as nanosponges where actually drug is encapsulated or loaded.

OBJECTIVE

In the present investigation, we observed the effect of various levels of crosslinking agents and beta-cyclodextrin concentrations on porosity, drug encapsulation, zeta potential and drug release by employing the quality by design approach to synthesize nanosponges rather than merely keeping both concentrations in proportions.

METHODS

We have slightly modified the method reported earlier i.e. melting method in which we have used rota evaporator receiver vessel for melting cross-linking agent and beta- cyclodextrin, rotated at 20 RPM at 100°C.

RESULTS

In a quality by design approach, we observed that out of four dependent variables i.e. porosity, drug loading, zeta potential and drug release, three significantly depend on the crosslinking of beta-cyclodextrin molecules which is highly appreciated by the amount of cross-linking agent present in the reaction. The pharmacokinetics of Imatinib loaded optimized nanosponges were compared with the reference product to observe the pattern of absorption and disposition.

CONCLUSION

Nanosponges synthesized by optimization technique could be effective means of anti-cancer drug oral administration as they encapsulate the drug effectively and offer a prolonged release of drug which gradually releases the drug and avoids unnecessary exposure of the drug.

Activatable cell-biomaterial interfacing with photo-caged peptides

We report an effective strategy to design activatable cell–material interfacing systems enabling photo-modulated cellular entry of cargoes and cell adhesion towards surfaces.

Spatio-temporally tailoring cell–material interactions is essential for developing smart delivery systems and intelligent biointerfaces. Here we report new photo-activatable cell–material interfacing systems that trigger cellular uptake of various cargoes and cell adhesion towards surfaces. To achieve this, we designed a novel photo-caged peptide which undergoes a structural transition from an antifouling ligand to a cell-penetrating peptide upon photo-irradiation. When the peptide is conjugated to ligands of interest, we demonstrate the photo-activated cellular uptake of a wide range of cargoes, including small fluorophores, proteins, inorganic (e.g., quantum dots and gold nanostars) and organic nanomaterials (e.g., polymeric particles), and liposomes. Using this system, we can remotely regulate drug administration into cancer cells by functionalizing camptothecin-loaded polymeric nanoparticles with our synthetic peptide ligands. Furthermore, we show light-controlled cell adhesion on a peptide-modified surface and 3D spatiotemporal control over cellular uptake of nanoparticles using two-photon excitation. We anticipate that the innovative approach proposed in this work will help to establish new stimuli-responsive delivery systems and biomaterials.

"Gate" engineered mesoporous silica nanoparticles for a double inhibition of drug efflux and particle exocytosis to enhance antitumor activity

"Gate" engineered mesoporous silica nanoparticles (MSN) have been extensively applied in cancer theranostics. Due to the complexity of tumor development and progression, with chemotherapy alone, it has often been difficult to achieve a good therapeutic effect. Currently, it has been shown that the combination with photothermal therapy overcomes the shortcoming of chemotherapy. In most studies, the photothermal effect has proven to accelerate drug release from nanocarriers and ablate malignant cells directly, but the influence on the intracellular fate of nanocarriers remains unknown. Herein, a lipophilic cyanine dye Cypate acting as a photothermal converting agent was conjugated on the external surface of MSN through a disulfide bond (MSN-Cy) and d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) was coated on the outside of the MSN-Cy via a hydrophobic interaction (TCMSN) to cover the pores, preventing drug preleakage in the circulation. The TCMSN underwent exocytosis through the lysosome-mediated pathway. Moderate heat induced by near-infrared light promoted lysosome disruption, which thus partly inhibited lysosome-mediated particle exocytosis. In the meantime, TPGS, as a P-glycoprotein inhibitor, blocked the drug efflux. This research elaborated the photothermal effect from a new perspective-inhibiting particle exocytosis. The as-designed "gate" engineered MSN realized a double inhibition of drug efflux and particle exocytosis from cancer cells, thus sustaining the drug action time and enhancing the antitumor activity.

Hydrophobic interaction mediated coating of pluronics on mesoporous silica nanoparticle with stimuli responsiveness for cancer therapy

In this research, a novel method was used to successfully stably coat Pluronic P123 on mesoporous silica nanoparticles (MSNs). Co-constructing a drug delivery system (DDS) with P123 and MSNs has not been previously reported. In this DDS, the coating of P123 was realized through a hydrophobic interaction with octadecyl chain-modified MSNs. The experiments found only Pluronic with an appropriate ratio of hydrophilic and lipophilic segments could keep the nanoassemblies stable. For comparison, nanoassemblies consisting of P123 and octadecyl chain-modified MSNs with or without a disulfide bond were prepared, which were denoted as PSMSNs and PMSNs, respectively. The disulfide bond was expected to endow the system with redox-responsiveness to enhance the therapeutic effect meanwhile decreasing the toxicity. A series of experiments including characterization of the nanoparticles, in vitro drug release, cell uptake and cellular drug release, in vitro cytotoxicity, cell migration and biodistribution of the nanoparticles were carried out. Compared with the PMSNs, PSMSNs displayed a redox-responsive drug release property not only in in vitro release text, but also on the cellular level. In addition, the cell migration experiments proved that the coating of P123 endowed the system with the ability of anti-metastasis. The accumulation of P123 in the tumor was enhanced after coating the MSNs by virtue of the 'EPR' effect of nanoparticles compared with the solution form.

Robust multi-responsive supramolecular hydrogel based on a mono-component host-guest gelator

Supramolecular hydrogels have been widely investigated, but the construction of stimuli-responsive mono-component host-guest hydrogels remains a challenge in that it is still hard to balance the solubility and gelation ability of the gelator. In this work, three azobenzene-modified β-cyclodextrin derivatives with different alkyl lengths (β-CD-Azo-Cn) have been synthesized. The length of the alkyl chain dramatically influences the solubility and gelation ability of β-CD derivatives in water. Among these derivatives, β-CD-Azo-C8 possesses the lowest minimum gelation concentration (MGC). Based on the host-guest interaction between β-CD and azobenzene units in aqueous solution, which is confirmed by UV-visible and ROESY NMR spectra, the gelators self-assemble and further interwine into networks through the hydrogen bonds on the surface of β-CD cavities. Hydrogels formed by mono-component gelators can collapse under external stimuli such as heating, competition guests and hosts, and UV irradiation. When the concentration of the gelator is more than 8 wt%, the hydrogel exhibits good self-supporting ability with a storage modulus higher than 104 Pa. The gel-sol transition temperature of the hydrogel is near body temperature, indicating its potential applications in biological materials.

Light-triggered C60 release from a graphene/cyclodextrin nanoplatform for the protection of cytotoxicity induced by nitric oxide

An ultraviolet (UV) light-triggered nanocarbon hybrid is developed for controlled C₆₀ release with excellent nitric oxide (NO) quenching ability. This nanocarrier, consisting of reduced graphene oxide (rGO) and β-cyclodextrin (β-CD), is capable of hosting azobenzene functionalized C₆₀ (Azo-C₆₀) synthesized by diazo chemistry. The hybridization of rGO, β-CD and Azo-C₆₀ enhances cellular uptake and limits the aggregation of C₆₀, and shows enhanced protective effects on NO-induced cytotoxicity. More interestingly, azo groups can reversibly switch between trans- and cis-isomers upon UV irradiation, so that the Azo-C₆₀ molecules exhibit photo-controlled release from rGO/β-CD in living cells. In vitro studies show that rGO/β-CD/C₆₀ treated with UV irradiation causes higher NO scavenging efficacy, which further significantly increases the cell viability from 32.6% to 88.4% at low loading levels (50 μg mL^-1). This represents an excellent NO quenching efficiency, better than other reports of the graphene/C₆₀ nanohybrids, and indicates that this material can be an effective nanoplatform to combat oxidative damage. As the host-guest chemistry and diazo chemistry are versatile and universally applicable, it is worth noting that the present strategy can also be applied in preparing other photo-responsive nanohybrids, which should be valuable for use in life science and materials science.

Visible-light-controllable drug release from multilayer-coated microneedles

A method for the generation of visible-light-controllable drug release polyelectrolyte multilayers on poly(l-lactide) (PLLA) microneedles is developed by host-guest chemistry. In response to visible light irradiation, model drugs encapsulated on polyelectrolyte multilayers transfer into the skin following brief microneedle application.

Extended release delivery of erlotinib glutathione nanosponge for targeting lung cancer

Systemic and uncontrolled administration of erlotinib hydrochloride (ETB) is associated with severe toxicity. A novel targeted and extended release nanosponge (NS) was synthesized from glutathione (GHS) by a one-step reaction between β-cyclodextrin and pyromellitic dianhydride at room temperature for delivery of ETB in lung cancer. Characterization studies were performed using sophisticated instruments. In-vitro release study was performed in the presence of incremental concentrations of GHS which was analyzed using HPLC. Cell cytotoxicity study was evaluated on human lung cancer (A549) cell lines. In-vivo tumour inhibition and biodistribution of ETB-loaded GHS-NS (ETB-NS) were performed on BALB/c mice. NS obtained was spherical, size 212 ± 2.45 nm and high drug entrapment (92.34 ± 5.31%) (p < .001). In-vitro extended drug release (76.89 ± 0.1% release at 168 h), which was directly proportional to the concentration of GHS, demonstrated tumour targeting. There was enhanced in-vitro cytotoxicity and 97.5% inhibition in tumour growth on administering NS when compared to plain ETB (48% inhibition) indicating targeting of NS to the tumour site. Biodistribution study and in-vivo tumour growth inhibition study revealed drug release to the cancerous cell, thus preventing unnecessary drug exposure. ETB-NS exhibits extended drug release proportional to the external GSH concentration.

Charge convertibility and near infrared photon co-enhanced cisplatin chemotherapy based on upconversion nanoplatform

Optimal nano-sized drug carrier requires long blood circulation, selective extravasation, and efficient cell uptake. Here we develop a charge-convertible nanoplatform based on Pt(IV) prodrug loaded NaYF₄:Yb,Tm upconversion nanoparticles (UCNs), followed by coating a layer of PEG-PAH-DMMA polymer (UCNs-Pt(IV)@PEG-PAH-DMMA). The polymer endows the platform with high biocompatibility, initial nano-size for prolonged blood circulation and selective extravasation. Especially, the anionic polymer can response to the mild acidic stimulus (pH ∼6.5) of tumor extracellular microenvironment and experience charge-shifting to a cationic polymer, resulting in electrostatic repulsion and releases of positive UCNs-Pt(IV). The positive UCNs-Pt(IV) nanoparticles have high affinity to negative cell membrane, leading to efficacious cell internalization. Simultaneously, the ultraviolet (UV) light emitted from UCNs upon near-infrared (NIR) light irradiation, together with the reductive glutathione (GSH) in cancer cells efficiently activate the Pt(IV) prodrug to highly cytotoxic Pt(II), realizing NIR photon improved chemotherapy. The experimental results reveal the charge convertibility, low adverse effect and markedly enhanced tumor ablation efficacy upon NIR laser irradiation of this smart nanoplatform. Moreover, combining the inherent upconversion luminescence (UCL) and computed tomography (CT) imaging capabilities, an alliance of cancer diagnosis and therapy has been achieved.

Stimulative nanogels with enhanced thermosensitivity for therapeutic delivery via β-cyclodextrin-induced formation of inclusion complexes

To explore the potential biomedical application of thermoresponsive nanosystems, it is important to enhance their thermosensitivity to improve the controllability in delivery of therapeutic agents. The present work develops multifunctional nanogels with enhanced thermosensitivity through copolymerization of N-isopropylacrylamide (NIPAM) and acrylic acid (AA) in the presence of β-cyclodextrin (β-CD), using N,N'-bis(acryloyl)cystamine (BAC) as a biodegradable crosslinker. The resulting nanogels display significantly improved sensitivity in deswelling (swelling) behavior upon temperature increase (decrease) around body temperature. The nanogels can effectively encapsulate doxorubicin (DOX), which can be released in an accelerated way under microenvironments that mimic intracellular reductive conditions and acidic tumor tissues. Release can also be remotely manipulated by increasing temperature. In vitro study indicates that the nanogels are quickly taken up by KB cells (a human epithelial carcinoma cell line), exerting improved anticancer cytotoxicity, showing their potential for delivery of therapeutic agents beyond anticancer drugs.

Specific On-site Assembly of Multifunctional Magnetic Nanocargos Based on Highly Efficient and Parallelized Bioconjugation: Toward Personalized Cancer Targeting Therapy

The rational design of particle-based cancer theranostic agents, combining diagnostic and therapeutic features in a single entity, has emerged as an effective approach toward personalized cancer therapy; however, creating a flexible assembly of specific targeting ligands with regard to a broad range of tumor tissues and cells is still challenging. Here, we present a convenient and highly variable on-site assembly strategy for the preparation of multifunctional doxorubicin (DOX)-loaded nanocargos with magnetic supraparticles (MSPs) as a core and redox-degradable poly(methylacrylic acid-co-N,N-bis(acryloyl) cystamine) (P(MAA-co-Cy) as the shell, which could be simultaneously modified with multiple targeting ligands through parallelized bioconjugation on the basis of a streptavidin-biotin (SA-BT) interaction. Under physiological conditions similar to those of the cytoplasm of tumor cells, DOX could be released in a controlled manner from these nanocargos to specific tumor sites, while dual-ligand modified nanocargos showed remarkable proliferation inhibition for the HeLa cells and the SK-OV-3 cells that overexpressed both folate as well as integrin receptors. The experimental results demonstrated that the on-site assembly strategy described herein opens access to highly efficient targeting drug delivery systems toward personalized cancer targeting therapy by incorporating functional diversity, which can be easily achieved through highly efficient and parallelized one-step bioconjugation.

A Photoresponsive Orthogonal Supramolecular Complex Based on Host-Guest Interactions

We synthesized a novel green-light-responsive tetra-ortho-isopropoxy-substituted azobenzene (ipAzo). Cis-ipAzo forms a strong host-guest complex with γ-cyclo dextrin (γ-CD) whereas trans-ipAzo binds weakly. This new photoresponsive host-guest interaction is reverse to the well-known azobenzene (Azo)/α-cyclodextrin (α-CD) complex, which is strong only between trans-Azo and α-CD. By combining the UV-light-responsive Azo/α-CD and green-light-responsive ipAzo/γ-CD host-guest complexes, a photoresponsive orthogonal supramolecular system is developed.

Supramolecular hydrogel based on high-solid-content mPECT nanoparticles and cyclodextrins for local and sustained drug delivery

A novel injectable and high-solid-content drug-loaded supramolecular hydrogel (PTX-mPECT NP/α-CD^gel) was prepared by self-assembly of inclusion complexes based on PTX-loaded mPECT nanoparticles and α-cyclodextrin.

Visible-light-responsive polymeric multilayers for trapping and release of cargoes via host–guest interactions

Visible-light-responsive layer-by-layer assembled polyelectrolyte multilayers are fabricated for reversible trapping and release of cargoes via azobenzene/cyclodextrin host–guest interactions.

Fabrication of "Plug and Play" Channels with Dual Responses by Host-Guest Interactions

The "Plug and Play" template can be individually or successively grafted by dual-responsive molecules on the α-CD modified channels by host-guest interactions and can be peeled off by UV irradiation. The artificial channels present six kinds of responses cycling among four states responding to three environment stimuli, as light, pH, and temperature.

Recent Advances of Using Hybrid Nanocarriers in Remotely Controlled Therapeutic Delivery

The development of hybrid biomaterials has been attracting great attention in the design of materials for biomedicine. The nanosized level of inorganic and organic or even bioactive components can be combined into a single material by this approach, which has created entirely new advanced compositions with truly unique properties for drug delivery. The recent advances in using hybrid nanovehicles as remotely controlled therapeutic delivery carriers are summarized with respect to different nanostructures, including hybrid host-guest nanoconjugates, micelles, nanogels, core-shell nanoparticles, liposomes, mesoporous silica, and hollow nanoconstructions. In addition, the controlled release of guest molecules from these hybrid nanovehicles in response to various remote stimuli such as alternating magnetic field, near infrared, or ultrasound triggers is further summarized to introduce the different mechanisms of remotely triggered release behavior. Through proper chemical functionalization, the hybrid nanovehicle system can be further endowed with many new properties toward specific biomedical applications.

Multifunctional Mesoporous Silica Nanoparticles with Thermal-Responsive Gatekeeper for NIR Light-Triggered Chemo/Photothermal-Therapy

In this work, a matrix metalloproteinase (MMP)-triggered tumor targeted mesoporous silica nanoparticle (MSN) is designed to realize near-infrared (NIR) photothermal-responsive drug release and combined chemo/photothermal tumor therapy. Indocyanine green (ICG) and doxorubicin (DOX) are both loaded in the MSN modified with thermal-cleavable gatekeeper (Azo-CD), which can be decapped by ICG-generated hyperthermia under NIR illumination. A peptidic sequence containing a short PEG chain, matrix metalloproteinase (MMP) substrate (PLGVR) and tumor cell targeting motif (RGD) are further decorated on the MSN via a host-guest interaction. The PEG chain can protect the MSN during the circulation and be cleaved off in the tumor tissues with overexpressed MMP, and then the RGD motif is switched on to target tumor cells. After the tumor-triggered targeting process, the NIR irradiation guided by ICG fluorescence can trigger cytosol drug release and realize combined chemo/photothermal therapy.

Highly Integrated Nano-Platform for Breaking the Barrier between Chemotherapy and Immunotherapy

Fighting metastasis is a major challenge in cancer therapy, and stimulation of the immune system is of particular importance in the treatment of metastatic cancers. Here, an integrated theranostic nanoplatform was developed for the efficient treatment of highly metastatic tumors. Versatile functions including "And" logically controlled drug release, prolonged circulation time, tumor targeting, and anti-metastasis were integrated into doxorubicin (DOX) loaded, highly integrated mesoporous silica nanoparticles (DOX@HIMSNs) for a systemic treatment of highly metastatic triple negative breast cancer (TNBC). It was found that the good therapeutic effect of DOX@HIMSN was only partially attributed to its anticancer cytotoxicity. Most importantly, DOX@HIMSN could induce anticancer immune responses including dendritic cell (DC) maturation and antitumor cytokine release. Compared with the traditional tumor chemotherapy, the integrated theranostic nanoplatform we developed not only improved the tumor specific cytotoxicity but also stimulated antitumor immune responses during the treatment.

Enhanced Precision of Nanoparticle Phototargeting in Vivo at a Safe Irradiance

A large proportion of the payload delivered by nanoparticulate therapies is deposited not in the desired target destination but in off-target locations such as the liver and spleen. Here, we demonstrate that phototargeting can improve the specific targeting of nanoparticles to tumors. The combination of efficient triplet-triplet annihilation upconversion (TTA-UC) and Förster resonance energy transfer (FRET) processes allowed in vivo phototargeting at a safe irradiance (200 mW/cm(2)) over a short period (5 min) using green light.

Charge-Convertible Carbon Dots for Imaging-Guided Drug Delivery with Enhanced in Vivo Cancer Therapeutic Efficiency

Carbon dots (CDs) are remarkable nanocarriers due to their promising optical and biocompatible capabilities. However, their practical applicability in cancer therapeutics is limited by their insensitive surface properties to complicated tumor microenvironment in vivo. Herein, a tumor extracellular microenvironment-responsive drug nanocarrier based on cisplatin(IV) prodrug-loaded charge-convertible CDs (CDs-Pt(IV)@PEG-(PAH/DMMA)) was developed for imaging-guided drug delivery. An anionic polymer with dimethylmaleic acid (PEG-(PAH/DMMA)) on the fabricated CDs-Pt(IV)@PEG-(PAH/DMMA) could undergo intriguing charge conversion to a cationic polymer in mildly acidic tumor extracellular microenvironment (pH ∼ 6.8), leading to strong electrostatic repulsion and release of positive CDs-Pt(IV). Importantly, positively charged nanocarrier displays high affinity to negatively charged cancer cell membrane, which results in enhanced internalization and effective activation of cisplatin(IV) prodrug in the reductive cytosol. The in vitro experimental results confirmed that this promising charge-convertible nanocarrier possesses better therapeutic efficiency under tumor extracellular microenvironment than normal physiological condition and noncharge-convertible nanocarrier. The in vivo experiments further demonstrated high tumor-inhibition efficacy and low side effects of the charge-convertible CDs, proving its capability as a smart drug nanocarrier with enhanced therapeutic effects. The present work provides a strategy to promote potential clinical application of CDs in the cancer treatment.

Programmed Nanococktail for Intracellular Cascade Reaction Regulating Self-Synergistic Tumor Targeting Therapy

In this work, a ZnO based nanococktail with programmed functions is designed and synthesized for self-synergistic tumor targeting therapy. The nanococktail can actively target tumors via specific interaction of hyaluronic acid (HA) with CD44 receptors and respond to HAase-rich tumor microenvironment to induce intracellular cascade reaction for controlled therapy. The exposed cell-penetrating peptide (R8) potentiates the cellular uptake of therapeutic nanoparticles into targeted tumor cells. Then ZnO cocktail will readily degrade in acidic endo/lysosomes and induce the production of desired reactive oxygen species (ROS) in situ. The destructive ROS not only leads to serious cell damage but also triggers the on-demand drug release for precise chemotherapy, thus achieving enhanced antitumor efficiency synergistically. After tail vein injection of ZnO cocktail, a favorable tumor apoptosis rate (71.2 ± 8.2%) is detected, which is significantly superior to that of free drug, doxorubicin (12.9 ± 5.2%). Both in vitro and in vivo studies demonstrate that the tailor-made ZnO cocktail with favorable biocompatibility, promising tumor specificity, and self-synergistically therapeutic capacity opens new avenues for cancer therapy.

Hollow Mesoporous Silica Nanocarriers with Multifunctional Capping Agents for In Vivo Cancer Imaging and Therapy

Efficient drug loading and selectivity in drug delivery are two key features of a good drug-carrier design. Here we report on such a drug carrier formed by using hollow mesoporous silica nanoparticles (HMS NPs) as the core and specifically designed multifunctional amphiphilic agents as the encapsulating shell. These nanocarriers combine the advantages of the HMS NP core (favorable physical and structural properties) and the versatility of an organic-based shell (e.g., specificity in chemical properties and modifiability). Moreover, both the properties of the core and the shell can be independently varied. The varied core and shell could then be integrated into a single device (drug carrier) to provide efficient and specific drug delivery. In vitro and in vivo data suggests that these drug nanocarriers are biocompatible and are able to deliver hydrophobic drugs selectively to target tumor cells. After the break of the pH-labile linkages in the shell, the drug payload can be released and the tumor cells are killed.

Hydrogen peroxide-responsive micelles self-assembled from a peroxalate ester-containing triblock copolymer

A novel copolymer was synthesized by using peroxalate esters as linkages and the formed micelles possessed specific H₂O₂ responsive reactivity.

Multifunctional theranostic nanoplatform for cancer combined therapy based on gold nanorods

Nanomaterials that integrate diagnostic and therapeutic functions within a single nanoplatform promise great advances in revolutionizing cancer therapy. A smart multifunctional theranostic drug-delivery system (DDS) based on gold nanorods (abbreviated as GNR/TSDOX) is designed for cancer-targeted imaging and imaging-guided therapy. In this intelligent theranostic DDS, the active targeting ligand biotin is introduced to track cancer sites in vivo. With the aid of photothermal/photoacoustic imaging, GNR/TSDOX can ablate cancer specifically and effectively. When stimulated with a single near-infrared (NIR) light source, this NIR light energy is effectively absorbed and converted into heat by GNR/TSDOX for localized photothermal therapy and the increase in temperature also further triggers the cascaded release of the anticancer drug for combined thermo-chemotherapy. More importantly, the in vivo cure effect can be well guided by regulating the irradiation time and intensity of the NIR light.

Pillar[5]arene based supramolecular prodrug micelles with pH induced aggregate behavior for intracellular drug delivery

A novel type of dual pH-responsive supramolecular prodrug micelles based on host-guest interactions of water-soluble pillar[5]arene (WP5) and methyl viologen functioned doxorubicin (MV-DOX) was prepared. It was found that the prodrug micelles could be aggregated upon acidic condition, which led to enhanced accumulation and better therapy effect.

Dual stimuli-responsive multi-drug delivery system for the individually controlled release of anti-cancer drugs

A dual stimuli-responsive multi-drug delivery system was developed for "cancer cocktail therapy". Upon UV irradiation, microcapsules could rapidly release the small-molecule drugs, and thereafter the macromolecular drugs would be released in the presence of MMP in the tumor cells. This system will find great potential as a novel chemotherapeutic combination for cancer treatment.

NIR light responsive core-shell nanocontainers for drug delivery

A novel near infrared (NIR)-triggered anticancer drug delivery system has been successfully constructed. Firstly, upconversion nanoparticles (UCNPs, NaYF₄:Tm,Yb@NaYF₄) were synthesized as a core and mesoporous silica (mSiO₂) as a shell to assemble the core-shell nanostructure (UCNP@mSiO₂) as the host. Supramolecular nanovalves based on α-cyclodextrin (α-CD) torus encircling a pimelic acid thread and being held in place by a cleavable stopper (nitrobenzyl alcohol) were used as nanoscopic caps to block the pore and inhibit drug diffusion. Upon irradiation with a 980 nm laser on the nanocomposites, the emitted ultraviolet light (UV, 360 nm) photocleaved the o-nitrobenzyl (ONB) photolabile group, causing these α-CD caps to dissociate from the stalk and release the drug. The "Ladder" pulsatile release-profiles, regulated by varying the intensity and time duration of NIR irradiation, further reveal the light-triggered release performance. In addition, without NIR irradiation, few immaturities ensure the high pharmacological efficacy. Moreover, the elaborate cell experiments, by using HeLa as model cancer cells, were also carried out to reveal the good biocompatibility, fast uptake and NIR light-sensitive toxicity. Therefore, the novel NIR light-triggered drug delivery system displays great potential for cancer therapy.