Controlled loading of albumin-drug conjugates ex vivo for enhanced drug delivery and antitumor efficacy

Revolutionizing Alzheimer's treatment: Harnessing human serum albumin for targeted drug delivery and therapy advancements

Alzheimer's disease (AD) is a neurodegenerative disorder initiated by amyloid-beta (Aβ) accumulation, leading to impaired cognitive function. Several delivery approaches have been improved for AD management. Among them, human serum albumin (HSA) is broadly employed for drug delivery and targeting the Aβ in AD owing to its biocompatibility, Aβ inhibitory effect, and nanoform, which showed blood-brain barrier (BBB) crossing ability via glycoprotein 60 (gp60) receptor and secreted protein acidic and rich in cysteine (SPARC) protein to transfer the drug molecules in the brain. Thus far, there is no previous review focusing on HSA and its drug delivery system in AD. Hence, the reviewed article aimed to critically compile the HSA therapeutic as well as drug delivery role in AD management. It also delivers information on how HSA-incorporated nanoparticles with surfaced embedded ligands such as TAT, GM1, and so on, not only improve BBB permeability but also increase neuron cell targetability in AD brain. Additionally, Aβ and tau pathology, including various metabolic markers likely BACE1 and BACE2, etc., are discussed. Besides, the molecular interaction of HSA with Aβ and its distinctive forms are critically reviewed that HSA can segregate Zn(II) and Cu(II) metal ions from Aβ owing to high affinity. Furthermore, the BBB drug delivery challenges in AD are addressed. Finally, the clinical formulation of HSA for the management of AD is critically discussed on how the HSA inhibits Aβ oligomer and fibril, while glycated HSA participates in amyloid plaque formation, i.e., β-structure sheet formation. This review report provides theoretical background on HSA-based AD drug delivery and makes suggestions for future prospect-related work.

Enhanced Tumor Site Accumulation and Therapeutic Efficacy of Extracellular Matrix-Drug Conjugates Targeting Tumor Cells

The extracellular matrix (ECM) engages in regulatory interactions with cell surface receptors through its constituent proteins and polysaccharides. Therefore, nano-sized extracellular matrix conjugated with doxorubicin (DOX) is utilized to produce extracellular matrix-drug conjugates (ECM-DOX) tailored for targeted delivery to cancer cells. The ECM-DOX nanoparticles exhibit rod-like morphology, boasting a commendable drug loading capacity of 4.58%, coupled with acid-sensitive drug release characteristics. Notably, ECM-DOX nanoparticles enhance the uptake by tumor cells and possess the ability to penetrate endothelial cells and infiltrate tumor multicellular spheroids. Mechanistic insights reveal that the internalization of ECM-DOX nanoparticle is facilitated through clathrin-mediated endocytosis and macropinocytosis, intricately involving hyaluronic acid receptors and integrins. Pharmacokinetic assessments unveil a prolonged blood half-life of ECM-DOX nanoparticles at 3.65 h, a substantial improvement over the 1.09 h observed for free DOX. A sustained accumulation effect of ECM-DOX nanoparticles at tumor sites, with drug levels in tumor tissues surpassing those of free DOX by several-fold. The profound therapeutic impact of ECM-DOX nanoparticles is evident in their notable inhibition of tumor growth, extension of median survival time in animals, and significant reduction in DOX-induced cardiotoxicity. The ECM platform emerges as a promising carrier for avant-garde nanomedicines in the realm of cancer treatment.

Rationalized landscape on protein-based cancer nanomedicine: Recent progress and challenges

The clinical advancement of protein-based nanomedicine has revolutionized medical professionals' perspectives on cancer therapy. Protein-based nanoparticles have been exploited as attractive vehicles for cancer nanomedicine due to their unique properties derived from naturally biomacromolecules with superior biocompatibility and pharmaceutical features. Furthermore, the successful translation of Abraxane™ (paclitaxel-based albumin nanoparticles) into clinical application opened a new avenue for protein-based cancer nanomedicine. In this mini-review article, we demonstrate the rational design and recent progress of protein-based nanoparticles along with their applications in cancer diagnosis and therapy from recent literature. The current challenges and hurdles that hinder clinical application of protein-based nanoparticles are highlighted. Finally, future perspectives for translating protein-based nanoparticles into clinic are identified.

Design, synthesis, and biological evaluation of cathepsin B cleavage albumin-binding SN38 prodrug in breast cancer

Here, we introduce a novel and effective approach utilizing a cathepsin B cleavage albumin-binding SN38 prodrug specifically designed for the treatment of metastatic breast cancer. Termed Mal-va-mac-SN38, our prodrug exhibits a unique ability to rapidly and covalently bind with endogenous albumin, resulting in the formation of HSA-va-mac-SN38. This prodrug demonstrates exceptional stability in human plasma. Importantly, HSA-va-mac-SN38 showcases an impressive enhancement in cellular uptake by 4T1 breast cancer cells, primarily facilitated through caveolin-mediated endocytosis. Intriguingly, the release of the active SN38, is triggered by the enzymatic activity of cathepsin B within the lysosomal environment. In vivo studies employing a lung metastasis 4T1 breast cancer model underscore the potency of HSA-va-mac-SN38. Histological immunohistochemical analyses further illuminate the multifaceted impact of our prodrug, showcasing elevated levels of apoptosis, downregulated expression of matrix metalloproteinases, and inhibition of angiogenesis, all critical factors contributing to the anti-metastatic effect observed. Biodistribution studies elucidate the capacity of Mal-va-mac-SN38 to augment tumor accumulation through covalent binding to serum albumin, presenting a potential avenue for targeted therapeutic interventions. Collectively, our findings propose a promising therapeutic avenue for metastatic breast cancer, through the utilization of a cathepsin B-cleavable albumin-binding prodrug.

Direct Assembly of Bioactive Nanoparticles Constructed from Polyphenol-Nanoengineered Albumin

Albumin nanoparticles are widely used in biomedicine due to their safety, low immunogenicity, and prolonged circulation. However, incorporating therapeutic molecules into these carriers faces challenges due to limited binding sites, restricting drug conjugation efficiency. We introduce a universal nanocarrier platform (X-UNP) using polyphenol-based engineering to incorporate phenolic moieties into albumin nanoparticles. Integration of catechol or galloyl groups significantly enhances drug binding and broadens the drug conjugation possibilities. Our study presents a library of X-UNP nanoparticles with improved drug-loading efficiency, achieving up to 96% across 10 clinically used drugs, surpassing conventional methods. Notably, ibuprofen-UNP nanoparticles exhibit a 5-fold increase in half-life compared with free ibuprofen, enhancing in vivo analgesic and anti-inflammatory effectiveness. This research establishes a versatile platform for protein-based nanosized materials accommodating various therapeutic agents in biotechnological applications.

Insight into the anti-proliferation activity and photoinduced NO release of four nitrosylruthenium isomeric complexes and their HSA complex adducts

Four Ru(II)-centered isomeric complexes [RuCl(5cqn)(Val)(NO)] (1-4) were synthesized with 5cqn (5-chloro-8-hydroxyquinoline) and chiral Val (Val = L- or D-valine) as co-ligand, and their structures were confirmed using the X-ray diffraction method. The cytotoxicity and photodynamic activity of the isomeric complexes and their human serum albumin (HSA) complex adducts were evaluated. Both the isomeric complexes and their HSA complex adducts significantly affected HeLa cell proliferation, with an IC50 value in the range of 0.3-0.5 μM. The photo-controlled release of nitric oxide (NO) in solution was confirmed using time-resolved Fourier transform infrared and electron paramagnetic resonance spectroscopy techniques. Furthermore, photoinduced NO release in living cells was observed using a selective fluorescent probe for NO. Moreover, the binding constants (Kb) of the complexes with HSA were calculated to be 0.17-1.98 × 104 M-1 and the average number of binding sites (n) was found to be close to 1, it can serve as a crucial carrier for delivering metal complexes. The crystal structure of the HSA complex adduct revealed that one [RuCl(H2O)(NO)(Val)]+ molecule binds to a pocket in domain I. This study provides insight into possible mechanism of metabolism and potential applications for nitrosylruthenium complexes.

Guanidine-modified albumin-MMAE conjugates with enhanced endocytosis ability

Aiming to address the insufficient endocytosis ability of traditional albumin drug conjugates, this paper reports elegant guanidine modification to improve efficacy for the first time. A series of modified albumin drug conjugates were designed and synthesized with different structures, including guanidine (GA), biguanides (BGA) and phenyl (BA), and different quantities of modifications. Then, the endocytosis ability and in vitro/vivo potency of albumin drug conjugates were systematically studied. Finally, a preferred conjugate A4 was screened, which contained 15 BGA modifications. Conjugate A4 maintains spatial stability similar to that of the unmodified conjugate AVM and could significantly enhance endocytosis ability (p*** = 0.0009) compared with the unmodified conjugate AVM. Additionally, the in vitro potency of conjugate A4 (EC50 = 71.78 nmol in SKOV3 cells) was greatly enhanced (approximately 4 times) compared with that of the unmodified conjugate AVM (EC50 = 286.00 nmol in SKOV3 cells). The in vivo efficacy of conjugate A4 completely eliminated 50% of tumors at 33 mg/kg, which was significantly better than the efficacy of conjugate AVM at the same dose (P** = 0.0026). In addition, theranostic albumin drug conjugate A8 was designed to intuitively realize drug release and maintain antitumor activity similar to conjugate A4. In summary, the guanidine modification strategy could provide new ideas for the development of new generational albumin drug conjugates.

Translational Challenges and Prospective Solutions in the Implementation of Biomimetic Delivery Systems

Biomimetic delivery systems (BDSs), inspired by the intricate designs of biological systems, have emerged as a groundbreaking paradigm in nanomedicine, offering unparalleled advantages in therapeutic delivery. These systems, encompassing platforms such as liposomes, protein-based nanoparticles, extracellular vesicles, and polysaccharides, are lauded for their targeted delivery, minimized side effects, and enhanced therapeutic outcomes. However, the translation of BDSs from research settings to clinical applications is fraught with challenges, including reproducibility concerns, physiological stability, and rigorous efficacy and safety evaluations. Furthermore, the innovative nature of BDSs demands the reevaluation and evolution of existing regulatory and ethical frameworks. This review provides an overview of BDSs and delves into the multifaceted translational challenges and present emerging solutions, underscored by real-world case studies. Emphasizing the potential of BDSs to redefine healthcare, we advocate for sustained interdisciplinary collaboration and research. As our understanding of biological systems deepens, the future of BDSs in clinical translation appears promising, with a focus on personalized medicine and refined patient-specific delivery systems.

A Versatile Platform to Generate Prodrugs with Rapid and Precise Albumin Hitchhiking and High Cargo Loading for Tumor-Targeted Chemotherapy

Due to its tumor homing and long serum half-life, albumin is an ideal drug carrier for chemotherapy. For endogenous albumin hitchhiking with high cargo loading, a trimeric albumin-binding domain (ABD), i.e., ABD-Tri is designed by fusing an ABD with high specificity and affinity for albumin to a self-trimerizing domain (Tri) with an additional cysteine residue. ABD-Tri is highly (40 mg L-1 ) expressed as soluble and trimeric proteins in Escherichia coli (E. coli). Once mixed together, ABD-Tri rapidly and specifically forms a stable complex with albumin under physiological conditions without obviously changing its receptor- and cell-binding and tumor-homing properties. Maleimide-modified prodrugs are highly effectively conjugated to ABD-Tri to produce homogenous ABD-Tri-prodrugs with triple cargo loading under physiological conditions by thiol-maleimide click chemistry. Unlike the maleimide moiety, which can only mediate time- and concentration-dependent albumin binding, ABD-Tri mediated fast (within several minutes) albumin binding of drugs even at extremely low concentrations (µg mL-1 ). Compared to maleimide-modified prodrugs, ABD-Tri-prodrugs exhibit better tumor homing and greater in vivo antitumor effect, indicating that conjugation of chemical drug to ABD-Tri outperforms maleimide modification for endogenous albumin hitchhiking. The results demonstrate that ABD-Tri may serve as a novel platform to produce albumin-binding prodrugs with high cargo-loading capacity for tumor-targeted chemotherapy.

Effective Prevention of Arterial Thrombosis with Albumin-Thrombin Inhibitor Conjugates

Thromboprophylaxis is indicated in patients at an elevated risk of developing thrombotic disorders, typically using direct oral anticoagulants or low-molecular-weight heparins. We postulated that transient thromboprophylaxis (days-weeks) could be provided by a single dose of an anticoagulant engineered for prolonged pharmacokinetics. In the present work, d-phenylalanyl-l-prolyl-l-arginine chloromethyl ketone (PPACK) was used as a model anticoagulant to test the hypothesis that conjugation of thrombin inhibitors to the surface of albumin would provide durable protection against thrombotic insults. Covalent conjugates were formed between albumin and PPACK using click chemistry, and they were tested in vitro using a thrombin activity assay and a clot formation assay. Thromboprophylactic efficacy was tested in mouse models of arterial thrombosis, both chemically induced (FeCl3) and following ischemia-reperfusion (transient middle cerebral artery occlusion; tMCAO). Albumin-PPACK conjugates were shown to have nanomolar potency in both in vitro assays, and following intravenous injection had prolonged circulation. Conjugates did not impact hemostasis (tail clipping) or systemic coagulation parameters in normal mice. Intravenous injection of conjugates prior to FeCl3-induced thrombosis provided significant protection against occlusion of the middle cerebral and common carotid arteries, and injection immediately following ischemia-reperfusion reduced stroke volume measured 3 days after injury by ∼40% in the tMCAO model. The data presented here provide support for the use of albumin-linked anticoagulants as an injectable, long-circulating, safe thromboprophylactic agent. In particular, albumin-PPACK provides significant protection against thrombosis induced by multiple mechanisms, without adversely affecting hemostasis.

Synthesis, cytotoxicity, and biomacromolecule binding: Three isomers of nitrosylruthenium complexes with bidentate bioactive molecules as co-ligands

Three isomeric nitrosylruthenium complexes [RuNO(Qn)(PZA)Cl] (P1, P2, and P3) with bioactive small molecules 8-hydroxyquinoline (Qn) and pyrazinamide (PZA) as co-ligands were synthesized, and their crystal structures were determined using X-ray diffraction technique. The cellular toxicity of the isomeric complexes was compared to understand the effects of the geometries on the biological activity of the complexes. Both the complexes and the human serum albumin (HSA) complex adducts affected the extent of proliferation of HeLa cells (IC₅₀: 0.77-1.45 μM). P2 showed prominent activity-induced cell apoptosis and arrested cell cycles at the G1 phase. The binding constants (K_b) of the complex with calf thymus DNA (CT-DNA) and HSA were quantitatively evaluated using fluorescence spectroscopy in the range of 0.17-1.56 × 10⁴ M^-1 and 0.88-3.21 × 10⁵ M^-1, respectively. The average binding site (n) number was close to 1. Moreover, the structure of HSA and the P2 complex adduct solved at the resolution of 2.48 Å revealed that one PZA-coordinated nitrosylruthenium complex bound at the subdomain I of HSA via a noncoordinative bond. HSA could serve as a potential nano-delivery system. This study provides a framework for the rational design of metal-based drugs.

Accelerating therapeutic protein design with computational approaches toward the clinical stage

Therapeutic protein, represented by antibodies, is of increasing interest in human medicine. However, clinical translation of therapeutic protein is still largely hindered by different aspects of developability, including affinity and selectivity, stability and aggregation prevention, solubility and viscosity reduction, and deimmunization. Conventional optimization of the developability with widely used methods, like display technologies and library screening approaches, is a time and cost-intensive endeavor, and the efficiency in finding suitable solutions is still not enough to meet clinical needs. In recent years, the accelerated advancement of computational methodologies has ushered in a transformative era in the field of therapeutic protein design. Owing to their remarkable capabilities in feature extraction and modeling, the integration of cutting-edge computational strategies with conventional techniques presents a promising avenue to accelerate the progression of therapeutic protein design and optimization toward clinical implementation. Here, we compared the differences between therapeutic protein and small molecules in developability and provided an overview of the computational approaches applicable to the design or optimization of therapeutic protein in several developability issues.

Albumin-hitchhiking: Fostering the pharmacokinetics and anticancer therapeutics

Nanotherapeutics demonstrate poor accumulation in the tumor microenvironment due to poor extravasation and penetration into the tumor. Therapeutics such as oligonucleotides, peptides and other biologicals suffer from low systemic half-life and rapid degradation. Albumin-hitchhiking has emerged as an effective strategy to enhance tumor-specific accumulation of various therapeutics. Hitchhiking on serum albumin (SA) have shown to improve biological half-life of various therapeutics including nanocarriers (NCs), biologics, oligonucleotides, vaccines, etc. In addition, passive and active accumulation of SA-riding therapeutics in the tumor, site-specific drug release, and SA-mediated endosomal escape have improved the potential of various anticancer modalities such as chemo-, immune-, vaccine, and gene therapies. In this review, we have discussed the advantages of employing SA-hitchhiking in anticancer therapies. In addition, vaccine strategies employing inherent lymph-nodes accumulating property of albumin have been discussed. We have presented a clinical overview of SA-hitchhiked formulations along with possible bottlenecks for improved clinical outcomes. We have also discussed the role of physiologically based pharmacokinetics (PBPK) modelling for efficient characterization of anti-cancer nanotherapeutics.

Biopolymeric Prodrug Systems as Potential Antineoplastic Therapy

Nowadays, cancer represents a major public health issue, a substantial economic issue, and a burden for society. Limited by numerous disadvantages, conventional chemotherapy is being replaced by new strategies targeting tumor cells. In this context, therapies based on biopolymer prodrug systems represent a promising alternative for improving the pharmacokinetic and pharmacologic properties of drugs and reducing their toxicity. The polymer-directed enzyme prodrug therapy is based on tumor cell targeting and release of the drug using polymer–drug and polymer–enzyme conjugates. In addition, current trends are oriented towards natural sources. They are biocompatible, biodegradable, and represent a valuable and renewable source. Therefore, numerous antitumor molecules have been conjugated with natural polymers. The present manuscript highlights the latest research focused on polymer–drug conjugates containing natural polymers such as chitosan, hyaluronic acid, dextran, pullulan, silk fibroin, heparin, and polysaccharides from Auricularia auricula.

Deciphering albumin-directed drug delivery by imaging

Albumin is the most abundant plasma protein, exhibits extended circulating half-life, and its properties have long been exploited for diagnostics and therapies. Many drugs intrinsically bind albumin or have been designed to do so, yet questions remain about true rate limiting factors that govern albumin-based transport and their pharmacological impacts, particularly in advanced solid cancers. Imaging techniques have been central to quantifying - at a molecular and single-cell level - the impact of mechanisms such as phagocytic immune cell signaling, FcRn-mediated recycling, oncogene-driven macropinocytosis, and albumin-drug interactions on spatial albumin deposition and related pharmacology. Macroscopic imaging of albumin-binding probes quantifies vessel structure, permeability, and supports efficiently targeted molecular imaging. Albumin-based imaging in patients and animal disease models thus offers a strategy to understand mechanisms, guide drug development and personalize treatments.

Synergic Antitumor Effect of Photodynamic Therapy and Chemotherapy Mediated by Nano Drug Delivery Systems

This review provides a summary of recent progress in the development of different nano-platforms for the efficient synergistic effect between photodynamic therapy and chemotherapy. In particular, this review focuses on various methods in which photosensitizers and chemotherapeutic agents are co-delivered to the targeted tumor site. In many cases, the photosensitizers act as drug carriers, but this review, also covers different types of appropriate nanocarriers that aid in the delivery of photosensitizers to the tumor site. These nanocarriers include transition metal, silica and graphene-based materials, liposomes, dendrimers, polymers, metal–organic frameworks, nano emulsions, and biologically derived nanocarriers. Many studies have demonstrated various benefits from using these nanocarriers including enhanced water solubility, stability, longer circulation times, and higher accumulation of therapeutic agents/photosensitizers at tumor sites. This review also describes novel approaches from different research groups that utilize various targeting strategies to increase treatment efficacy through simultaneous photodynamic therapy and chemotherapy.

SN38-based albumin-binding prodrug for efficient targeted cancer chemotherapy

Developing new therapeutic strategies that damage tumour cells without harming normal tissues is among the primary obstacles in chemotherapy. In this study, a novel β-glucuronidase-sensitive albumin-binding prodrug was designed and synthesized to selectively deliver the drug SN38 to tumour sites and maximize its efficacy. After intravenous administration, the prodrug Mal-glu-SN38 covalently bound to plasma albumin through the Michael addition, enabling it to accumulate in the tumour and release SN38 when triggered by extracellular β-glucuronidase. Compared to irinotecan, Mal-glu-SN38 displayed a slower plasma clearance and increased drug exposure over time. Moreover, Mal-glu-SN38 caused an increase in tumour-site accumulation of both the albumin-prodrug conjugate and free SN38 released from albumin conjugate when compared with irinotecan. After administration of multiple doses, Mal-glu-SN38 also significantly delayed the tumour growth, resulting in an impressive reduction or even disappearance of tumours (67% of mice cured) without causing any observable side effects.

Black phosphorus assisted polyionic micelles with efficient PTX loading for remotely controlled release and synergistic treatment of drug-resistant tumors

Nanomedicines have been widely used in the effective delivery of chemotherapeutic drugs due to their advantages such as increasing the half-life of drugs, selectively targeting tumor tissues, and thus reducing systemic toxicity. However, the low drug entrapment rate and the difficulty of real-controlled release at tumor sites hinder their further clinical translations. Here we have developed biodegradable polyionic micelles (PD-M) to facilitate black phosphorus (BP) encapsulation (PD-M@BP) for improved drug loading. With the introduction of BP, PTX-loaded PD-M@BP (PD-M@BP/PTX) with sizes of 124-162 nm exhibited superior encapsulation efficiency over 94% and excellent colloidal stability. Meanwhile, PD-M well protected BP from fast degradation to show the good photothermal performance under near-infrared (NIR) irradiation, thus achieving the remotely controlled fast PTX release due to micelle core melting and dissociation, accompanied by the synergistic photothermal tumor therapy. The in vivo results demonstrated that the PD-M@BP/PTX nanosystem not only realized significant inhibition of multi-drug resistant (MDR) cervical tumors (HeLa/PTXR tumor) by remote NIR-regulation, but also reduced the potential damage of chemotherapeutic drugs to the whole body, rendering these hybrid nanosystems as great tools to treat MDR tumors synergistically.

Berberine-Albumin Nanoparticles: Preparation, Thermodynamic Study and Evaluation Their Protective Effects Against Oxidative Stress in Primary Neuronal Cells as a Model of Alzheimer's Disease

Berberine has shown an outstanding antioxidant activity, however the low bioavailability limits its applications in pharmaceutical platforms. Therefore, in this paper, after fabrication of the berberine-HSA nanoparticles by desolvation method, they were well characterized by TEM, SEM, DLS, and FTIR techniques. Afterwards the interaction of HSA and the berberine was evaluated by molecular docking analysis. Finally, the antioxidant activity of the berberine-HSA nanoparticles against H₂O₂-induced oxidative stress in cultured neurons as a model of AD was evaluated by cellular assays. The results showed that the prepared berberine-HSA nanoparticles have a spherical-shaped morphology with a size of around 100 nm and zeta potential value of -31.84 mV. The solubility value of nanoparticles was calculated to be 40.27%, with a berberine loading of 19.37%, berberine entrapment efficiency of 70.34%, and nanoparticles yield of 88.91%. Also, it was shown that the berberine is not significantly released from HSA nanoparticles within 24 hours. Afterwards, molecular docking investigation revealed that berberine spontaneously interacts with HSA through electrostatic interaction. Finally, cellular assays disclosed that the pretreatment of neuronal cultures with berberine-HSA nanoparticles decreased the H₂O₂-stimulated cytotoxicity and relevant morphological changes and enhanced the CAT activity. In conclusion, it can be indicated that the nanoformulation of the berberine can be used as a promising platform for inhibition of oxidative damage-induced Alzheimer's disease (AD).

Structural and Photodynamic Studies on Nitrosylruthenium-Complexed Serum Albumin as a Delivery System for Controlled Nitric Oxide Release

How to deliver nitric oxide (NO) to a physiological target and control its release quantitatively is a key issue for biomedical applications. Here, a water-soluble nitrosylruthenium complex, [(CH₃)₄N][RuCl₃(5cqn)(NO)] (H5cqn = 5-chloro-8-quinoline), was synthesized, and its structure was confirmed with ¹H NMR and X-ray crystal diffraction. Photoinduced NO release was investigated with time-resolved Fourier transform infrared and electron paramagnetic resonance (EPR) spectroscopies. The binding constant of the [RuCl₃(5cqn)(NO)]^- complex with human serum albumin (HSA) was determined by fluorescence spectroscopy, and the binding mode was identified by X-ray crystallography of the HSA and Ru-NO complex adduct. The crystal structure reveals that two molecules of the Ru-NO complex are located in the subdomain IB, which is one of the major drug binding regions of HSA. The chemical structures of the Ru complexes were [RuCl₃(5cqn)(NO)]^- and [RuCl₃(Glycerin)NO]^-, in which the electron densities for all ligands to Ru are unambiguously identified. EPR spin-trapping data showed that photoirradiation triggered NO radical generation from the HSA complex adduct. Moreover, the near-infrared image of exogenous NO from the nitrosylruthenium complex in living cells was observed using a NO-selective fluorescent probe. This study provides a strategy to design an appropriate delivery system to transport NO and metallodrugs in vivo for potential applications.

Preparation Optimization of Bovine Serum Albumin Nanoparticles and Its Application for siRNA Delivery

BACKGROUND

siRNA brings hope for cancer therapy. However, there are many obstacles for application of siRNA in clinical. Because of the excellent biocompatibility, non-toxicity and non-immunogenicity of bovine serum albumin (BSA), BSA-based nanoparticles have been widely designed as a drug carrier system.

METHODS

The optimal formula for BSA NPs preparation was investigated by central composite design response surface methodology (CCD-RSM), BSA-based survivin-siRNA delivery system (BSA NPs/siRNA) was characterized by dynamic light scattering, atomic force microscope, transmission electron microscope and Bradford method. The in vitro anti-tumor effect and mechanism of BSA NPs were investigated by confocal microscopic imaging, MTT assay, RT-qPCR and ELISA analysis. Moreover, the anti-tumor effect, distribution and biosafety of BSA NPs were studied in vivo.

RESULTS

The optimal formula for BSA NPs was settled to be 20 mg/mL for BSA concentration, 9 for pH value, 136% for crosslinking degree and 1.6 mL/min for speed of ethanol addition. BSA NPs/siRNA could remain stable at 4°C for 4 weeks and protect siRNA from degradation by RNase A. Besides, BSA NPs/siRNA could maintain a sustained release of siRNA and promote the uptake of siRNA significantly. The survivin-mRNA level and the survivin-protein level were decreased by 55% ± 1.6% and 54% ± 1.6% separately. The in vivo tumor inhibition results suggested that the tumor inhibition rate of BSA NPs/siRNA-treated group was 54% ± 12% and was similar with that of DOX-treated group (57% ± 9.2%, P > 0.05). The biosafety results confirmed that BSA NPs/siRNA could not induce significant damages to the main organs and blood in vivo.

CONCLUSION

These results demonstrated that CCD-RSM was an effective tool for preparation analysis, and the BSA NPs/siRNA was a promising system for siRNA-based gene therapy.

Albumin-binding prodrugs via reversible iminoboronate forming nanoparticles for cancer drug delivery

Albumin-based nanomedicines are important nanoplatforms for cancer drug delivery. The drugs are either physically encapsulated or covalently conjugated to albumin or albumin-based nanosystems. Physical encapsulation is advantageous due to requiring no chemical modification of drug molecules, but many drugs, for instance, camptothecin (CPT) and curcumin (CCM), though very hydrophobic, can't be loaded in or form nanoformulations with albumin. Herein, we demonstrate prodrugs readily binding to proteins via iminoboronates and forming nanoparticles for cancer drug delivery. CPT and CCM were functionalized with 2-acetylphenylboronic acid (2-APBA) to produce prodrugs CPT-SS-APBA and CCM- APBA. The prodrugs bound to bovine serum albumin (BSA) via formation of iminoboronates and the produced BSA/prodrug readily self-assembled into well-defined nanoparticles with high loading efficiency, improved colloidal stability, and much-improved pharmacokinetics. The nanoparticles effectively released drugs in the intracellular acidic environment or the cytosol rich in glutathione (GSH). In vivo, the nanoparticles showed enhanced anticancer efficacy compared with clinically used irinotecan or sorafenib in subcutaneous 4 T1 or HepG2 tumor models. This work demonstrates a versatile protein-binding prodrug platform applicable to protein-based drug formulations and even antibody-drug conjugates.

Precise design strategies of nanomedicine for improving cancer therapeutic efficacy using subcellular targeting

Therapeutic efficacy against cancer relies heavily on the ability of the therapeutic agents to reach their final targets. The optimal targets of most cancer therapeutic agents are usually biological macromolecules at the subcellular level, which play a key role in carcinogenesis. Therefore, to improve the therapeutic efficiency of drugs, researchers need to focus on delivering not only the therapeutic agents to the target tissues and cells but also the drugs to the relevant subcellular structures. In this review, we discuss the most recent construction strategies and release patterns of various cancer cell subcellular-targeting nanoformulations, aiming at providing guidance in the overall design of precise nanomedicine. Additionally, future challenges and potential perspectives are illustrated in the hope of enhancing anticancer efficacy and accelerating the translational progress of precise nanomedicine.

Serum protein-based nanoparticles for cancer diagnosis and treatment

Serum protein as naturally essential biomacromolecules has recently emerged as a versatile carrier for diagnostic and therapeutic drug delivery for cancer nanomedicine with superior biocompatibility, improved pharmacokinetics and enhanced targeting capacity. A variety of serum proteins have been utilized for drug delivery, mainly including albumin, ferritin/apoferritin, transferrin, low-density lipoprotein, high-density lipoprotein and hemoglobin. As evidenced by the success of paclitaxel-bound albumin nanoparticles (Abraxane^TM), serum protein-based nanoparticles have gained attractive attentions for precise biological design and potential clinical application. In this review, we summarize the general design strategies, targeting mechanisms and recent development of serum protein-based nanoparticles in the field of cancer nanomedicine. Moreover, we also concisely specify the current challenges to be addressed for a bright future of serum protein-based nanomedicines.