Novel carrier-free nanoparticles composed of 7-ethyl-10-hydroxycamptothecin and chlorin e6: Self-assembly mechanism investigation and in vitro/in vivo evaluation

Chlorin e6: a promising photosensitizer of anti-tumor and anti-inflammatory effects in PDT

Photodynamic therapy (PDT) involves the activation of photosensitizers (PSs) by visible laser light at the target site to catalyze the production of reactive oxygen species, resulting in tumor cell death and blood vessel closure. The efficacy of PDT depends on the PSs, the amount of oxygen, and the intensity of the excitation laser. PSs have been extensively researched, and great efforts have been made to develop an ideal photosensitizer. Chlorin-e6 is an FDA-approved second-generation PSs that has attracted widespread research interest in the medical field, especially with respect to antitumor and anti-inflammatory activity. Chlorin-e6 possesses the advantages of a large absorption coefficient, high strength, low residue in the body, and relatively high safety and thus has promising application prospects. Here we review the use of chlorin-e6 in PDT and discuss the prospects of further development of this technology.

Active herbal ingredients and drug delivery design for tumor therapy: a review

Active herbal ingredients are gaining recognition for their potent anti-tumor efficacy, attributable to various mechanisms including tumor cell inhibition, immune system activation, and tumor angiogenesis inhibition. Recent studies have revealed that numerous anti-tumor herbal ingredients, such as ginsenosides, ursolic acid, oleanolic acid, and Angelica sinensis polysaccharides, can be utilized to develop smart drug carriers like liposomes, micelles, and nanoparticles. These carriers can deliver active herbal ingredients and co-deliver anti-tumor drugs to enhance drug accumulation at tumor sites, thereby improving anti-tumor efficacy. This study provides a comprehensive analysis of the mechanisms by which these active herbal ingredients-derived carriers enhance therapeutic outcomes. Additionally, it highlights the structural properties of these active herbal ingredients, demonstrating how their unique features can be strategically employed to design smart drug carriers with improved anti-tumor efficacy. The insights presented aim to serve as a reference and guide future innovations in the design and application of smart drug carriers for cancer therapy that leverage active herbal ingredients.

Toward the Integration of Machine Learning and Molecular Modeling for Designing Drug Delivery Nanocarriers

The pioneering work on liposomes in the 1960s and subsequent research in controlled drug release systems significantly advances the development of nanocarriers (NCs) for drug delivery. This field is evolved to include a diverse array of nanocarriers such as liposomes, polymeric nanoparticles, dendrimers, and more, each tailored to specific therapeutic applications. Despite significant achievements, the clinical translation of nanocarriers is limited, primarily due to the low efficiency of drug delivery and an incomplete understanding of nanocarrier interactions with biological systems. Addressing these challenges requires interdisciplinary collaboration and a deep understanding of the nano-bio interface. To enhance nanocarrier design, scientists employ both physics-based and data-driven models. Physics-based models provide detailed insights into chemical reactions and interactions at atomic and molecular scales, while data-driven models leverage machine learning to analyze large datasets and uncover hidden mechanisms. The integration of these models presents challenges such as harmonizing different modeling approaches and ensuring model validation and generalization across biological systems. However, this integration is crucial for developing effective and targeted nanocarrier systems. By integrating these approaches with enhanced data infrastructure, explainable AI, computational advances, and machine learning potentials, researchers can develop innovative nanomedicine solutions, ultimately improving therapeutic outcomes.

Research progress in tumor therapy of carrier-free nanodrug

Carrier-free nanodrugs are a novel type of drug constructed by the self-assembly of drug molecules without carrier involvement. They have the characteristics of small particle size, easy penetration of various barriers, targeting tumors, and efficient release. In recent years, carrier-free nanodrugs have become a hot topic in tumor therapy as they solve the problems of low drug loading, poor biocompatibility, and low uptake efficiency of carrier nanodrugs. A series of recent studies have shown that carrier-free nanodrugs play a vital role in the treatment of various tumors, with similar or better effects than carrier nanodrugs. Based on the literature published in the past decades, this paper first summarizes the recent progress in the assembly modes of carrier-free nanodrugs, then describes common therapeutic modalities of carrier-free nanodrugs in tumor therapy, and finally depicts the existing challenges along with future trends of carrier-free nanodrugs. We hope that this review can guide the design and application of carrier-free nanodrugs in the future.

Natural-product-based, carrier-free, noncovalent nanoparticles for tumor chemo-photodynamic combination therapy

Cancer, with its diversity, heterogeneity, and complexity, is a significant contributor to global morbidity, disability, and mortality, highlighting the necessity for transformative treatment approaches. Photodynamic therapy (PDT) has aroused continuous interest as a viable alternative to conventional cancer treatments that encounter drug resistance. Nanotechnology has brought new advances in medicine and has shown great potential in drug delivery and cancer treatment. For precise and efficient therapeutic utilization of such a tumor therapeutic approach with high spatiotemporal selectivity and minimal invasiveness, the carrier-free noncovalent nanoparticles (NPs) based on chemo-photodynamic combination therapy is essential. Utilizing natural products as the foundation for nanodrug development offers unparalleled advantages, including exceptional pharmacological activity, easy functionalization/modification, and well biocompatibility. The natural-product-based, carrier-free, noncovalent NPs revealed excellent synergistic anticancer activity in comparison with free photosensitizers and free bioactive natural products, representing an alternative and favorable combination therapeutic avenue to improve therapeutic efficacy. Herein, a comprehensive summary of current strategies and representative application examples of carrier-free noncovalent NPs in the past decade based on natural products (such as paclitaxel, 10-hydroxycamptothecin, doxorubicin, etoposide, combretastatin A4, epigallocatechin gallate, and curcumin) for tumor chemo-photodynamic combination therapy. We highlight the insightful design and synthesis of the smart carrier-free NPs that aim to enhance PDT efficacy. Meanwhile, we discuss the future challenges and potential opportunities associated with these NPs to provide new enlightenment, spur innovative ideas, and facilitate PDT-mediated clinical transformation.

Self-assembled nanodrug delivery systems for anti-cancer drugs from traditional Chinese medicine

Traditional Chinese medicine (TCM) is a combination of raw herbs and herbal extracts with a plethora of documented beneficial bioactivities, which has unique advantages in anti-tumor therapy, and many of its major bioactive molecules have been identified in recent years due to advances in chemical separation and structural analysis. However, the major chemical classes of plant-derived bioactive compounds frequently possess chemical properties, including poor water solubility, stability, and bioavailability, that limit their therapeutic application. Alternatively, natural small molecules (NSMs) containing these components possess modifiable groups, multiple action sites, hydrophobic side chains, and a rigid skeleton with self-assembly properties that can be exploited to construct self-assembled nanoparticles with therapeutic effects superior to their individual constituents. For instance, the construction of a self-assembled nanodrug delivery system can effectively overcome the strong hydrophobicity and poor in vivo stability of NSMs, thereby greatly improving their bioavailability and enhancing their anti-tumor efficacy. This review summarizes the self-assembly methods, mechanisms, and applications of a variety of NSMs, including terpenoids, flavonoids, alkaloids, polyphenols, and saponins, providing a theoretical basis for the subsequent research on NSMs and the development of SANDDS.

Application of molecular dynamics simulation in self-assembled cancer nanomedicine

Self-assembled nanomedicine holds great potential in cancer theragnostic. The structures and dynamics of nanomedicine can be affected by a variety of non-covalent interactions, so it is essential to ensure the self-assembly process at atomic level. Molecular dynamics (MD) simulation is a key technology to link microcosm and macroscale. Along with the rapid development of computational power and simulation methods, scientists could simulate the specific process of intermolecular interactions. Thus, some experimental observations could be explained at microscopic level and the nanomedicine synthesis process would have traces to follow. This review not only outlines the concept, basic principle, and the parameter setting of MD simulation, but also highlights the recent progress in MD simulation for self-assembled cancer nanomedicine. In addition, the physicochemical parameters of self-assembly structure and interaction between various assembled molecules under MD simulation are also discussed. Therefore, this review will help advanced and novice researchers to quickly zoom in on fundamental information and gather some thought-provoking ideas to advance this subfield of self-assembled cancer nanomedicine.

Chlorin e6: A Promising Photosensitizer in Photo-Based Cancer Nanomedicine

Conventional cancer treatment modalities are often associated with major therapeutic limitations and severe side effects. Photodynamic therapy is a localized noninvasive mode of treatment that has given a different direction to cancer research due to its effectivity against a wide range of cancers and minimal side effects. A photosensitizer is the key component of photodynamic therapy (PDT) that generates cytotoxic reactive oxygen species to eradicate cancer cells. As the therapeutic effectivity of PDT greatly depends upon the photosensitizer, great efforts have been made to search for an ideal photosensitizer. Chlorin e6 is a FDA approved second generation photosensitizer that meets the desired clinical properties for PDT. It is known for its high reactive oxygen species (ROS) generation ability and anticancer potency against many types of cancer. Hydrophobicity is a major drawback of Ce6 that leads to its poor biodistribution and rapid clearance from the circulatory system. To overcome this drawback, researchers have designed and fabricated several types of nanosystems, which can enhance Ce6 solubility and thereby enhance its bioavailability. These nanosystems also improve tumor accumulation of Ce6 by selectively targeting the cancer cells through passive and active targeting. In addition, Ce6 has been employed in many combination therapies like chemo-photodynamic therapy, photoimmunotherapy, and combined photodynamic-photothermal therapy. A combination therapy is more curative than a single therapy due to the synergistic effects of individual therapies. Ce6-based nanosystems for combination therapies have shown excellent results in various studies and provide a promising platform for cancer treatment.

Recent Progress in Carrier-Free Nanomedicine for Tumor Phototherapy

Safe and effective strategies are urgently needed to fight against the life-threatening diseases of various cancers. However, traditional therapeutic modalities, such as radiotherapy, chemotherapy and surgery, exhibit suboptimal efficacy for malignant tumors owing to the serious side effects, drug resistance and even relapse. Phototherapies, including photodynamic therapy (PDT) and photothermal therapy (PTT), are emerging therapeutic strategies for localized tumor inhibition, which can produce a large amount of reactive oxygen species (ROS) or elevate the temperature to initiate cell death by non-invasive irradiation. In consideration of the poor bioavailability of phototherapy agents (PTAs), lots of drug delivery systems have been developed to enhance the tumor targeted delivery. Nevertheless, the carriers of drug delivery systems inevitably bring biosafety concerns on account of their metabolism, degradation, and accumulation. Of note, carrier-free nanomedicine attracts great attention for clinical translation with synergistic antitumor effect, which is characterized by high drug loading, simplified synthetic method and good biocompatibility. In this review, the latest advances of phototherapy with various carrier-free nanomedicines are summarized, which may provide a new paradigm for the future development of nanomedicine and tumor precision therapy.

Fabrication, Evaluation, and Antioxidant Properties of Carrier-Free Curcumin Nanoparticles

Curcumin (Cur), a natural hydrophobic polyphenolic compound, exhibits multiple beneficial biological activities. However, low water solubility and relative instability hinder its application in food fields. In this study, carrier-free curcumin nanoparticles (CFC NPs) were prepared by adding the DMSO solution of Cur into DI water under continuous rapid stirring. The morphology of CFC NPs was a spherical shape with a diameter of 65.25 ± 2.09 nm (PDI = 0.229 ± 0.107), and the loading capacity (LC) of CFC NPs was as high as 96.68 ± 0.03%. The thermal property and crystallinity of CFC NPs were investigated by XRD. Furthermore, the CFC NPs significantly accelerated the release of Cur in vitro owing to its improved water dispersibility. Importantly, CFC NPs displayed significantly improved DPPH radical scavenging activity. Overall, all these results suggested that CFC NPs would be a promising vehicle to widen the applications of Cur in food fields.

Multicomponent carrier-free nanodrugs for cancer treatment

Nanocarriers can be used to deliver insoluble anticancer drugs to optimize therapeutic efficacy. However, the potential toxicity of nanocarriers cannot be ignored. Carrier-free nanodrugs are emerging safe drug delivery systems, which are composed of multiple components, such as drugs, bioactive molecules and functional ingredients, avoiding the usage of inert carrier materials and offering advantages that include high drug loading, low toxicity, synergistic therapy, versatile design, and easy surface functionalization. Therefore, how to design multicomponent carrier-free nanodrugs is becoming a priority. In this review, the common strategies for rapid construction of multicomponent carrier-free nanodrugs are briefly explored from the perspective of methodology. The properties of organic-organic, organic-inorganic and inorganic-inorganic multiple carrier-free nanosystems are analyzed according to wettability and in-depth understanding is provided. Further advances in the applications of multiple carrier-free nanodrugs are outlined in anticipation of grasping the intrinsic nature for the design and development of carrier-free nanodrugs.

Preparation of carrier-free astaxanthin nanoparticles with improved antioxidant capacity

Astaxanthin (AST), a red pigment of the carotenoids, has various advantageous biological activities. Nevertheless, the wide application of AST is restricted due to its poor water solubility and highly unsaturated structure. To overcome these limitations, carrier-free astaxanthin nanoparticles (AST-NPs) were fabricated through the anti-solvent precipitation method. The AST-NPs had a small particle size, negative zeta potential and high loading capacity. Analysis of DSC and XRD demonstrated that amorphous AST existed in AST-NPs. In comparison with free AST, AST-NPs displayed enhanced stability during storage. Besides, it also showed outstanding stability when exposed to UV light. Furthermore, the antioxidant capacity of AST-NPs was significantly increased. In vitro release study showed that AST-NPs significantly delayed the release of AST in the releasing medium. These findings indicated that AST-NPs would be an ideal formulation for AST, which could contribute to the development of novel functional foods.

Overview of Nanoparticle-Based Approaches for the Combination of Photodynamic Therapy (PDT) and Chemotherapy at the Preclinical Stage

Simple Summary

The present review represents the outstanding and promising recent literature reports (2017–2022) on nanoparticle-based formulations developed for anticancer therapy with photodynamic therapy (PDT), photosensitizers, and chemotherapeutics. Besides brief descriptions of chemotherapeutics’ classification and of PDT mechanisms and limitations, several examples of nanosystems endowed with different responsiveness (e.g., acidic pH and reactive oxygen species) and peculiarity (e.g., tumor oxygenation capacity, active tumor targeting, and biomimetic features) are described, and for each drug combination, in vitro and in vivo results on preclinical cancer models are reported.

Abstract

The widespread diffusion of photodynamic therapy (PDT) as a clinical treatment for solid tumors is mainly limited by the patient’s adverse reaction (skin photosensivity), insufficient light penetration in deeply seated neoplastic lesions, unfavorable photosensitizers (PSs) biodistribution, and photokilling efficiency due to PS aggregation in biological environments. Despite this, recent preclinical studies reported on successful combinatorial regimes of PSs with chemotherapeutics obtained through the drugs encapsulation in multifunctional nanometric delivery systems. The aim of the present review deals with the punctual description of several nanosystems designed not only with the objective of co-transporting a PS and a chemodrug for combination therapy, but also with the goal of improving the therapeutic efficacy by facing the main critical issues of both therapies (side effects, scarce tumor oxygenation and light penetration, premature drug clearance, unspecific biodistribution, etc.). Therefore, particular attention is paid to the description of bio-responsive drugs and nanoparticles (NPs), targeted nanosystems, biomimetic approaches, and upconverting NPs, including analyzing the therapeutic efficacy of the proposed photo-chemotherapeutic regimens in in vitro and in vivo cancer models.

Multispectroscopic and synergistic antioxidant study on the combined binding of caffeic acid and (-)-epicatechin gallate to lysozyme

The binding of caffeic acid (CA) and/or (-)-epicatechin gallate (ECG) to lysozyme was investigated by multispectroscopic methods and molecular docking. The effects of the single and combined binding on the structure, activity and stability of lysozyme and the synergistic antioxidant activity of CA and ECG were also studied. Fluorescence quenching spectra, time-resolved fluorescence spectra, and UV-vis absorption difference spectra all ascertained the static quenching mechanism of lysozyme by CA/ECG. Thermodynamic parameters indicated that CA and ECG competitively bound to lysozyme, and CA had a stronger binding affinity, which was consistent with the results of molecular docking. Hydrogen bonding, van der Waals' force and electrostatic interaction were the main driving forces for the binding process. Synchronous fluorescence spectra displayed that the interaction of CA/ECG exposed the tryptophan residues of lysozyme to a more hydrophilic environment. Circular dichroism spectroscopy, Fourier transform infrared spectroscopy and dynamic light scattering indicated that the binding of CA and/or ECG to lysozyme resulted in the change of the secondary structure and increased the particle size of lysozyme. The binding of CA and/or ECG to lysozyme inhibited the enzyme activity and enhanced the thermal stability of lysozyme. The combined application of CA and ECG showed antioxidant synergy which was influenced by the encapsulation of lysozyme and cellular uptake. In summary, this work provides theoretical guidance for lysozyme as a carrier for the combined application of CA and ECG.

Glutathione-sensitive IPI-549 nanoparticles synergized with photodynamic Chlorin e6 for the treatment of breast cancer

We combined phosphoinositol-3-kinin inhibitor IPI-549 and photodynamic Chlorin e6 (Ce6) on carboxymethyl chitosan to develop a novel drug delivery nanoparticle (NP) system (Ce6/CMCS-DSP-IPI549) and evaluate its glutathione (GSH) sensitivity and targeting ability for breast cancer treatment. The NPs were spherical with a uniform size of 218.8 nm, a stable structure over 7 days. The maximum encapsulation efficiency was 64.42%, and NPs drug loading was 8.05%. The NPs released drugs within tumor cells due to their high GSH concentration, while they maintained structural integrity in normal cells, which have low GSH concentration. The cumulative release rates of IPI-549 and Ce6 at 108 h were 70.67% and 40.35% (at GSH 10 mM) and 8.11% and 2.71% (at GSH 2μM), respectively. The NPs showed a strong inhibitory effect on 4T1 cells yet did not affect human umbilical vein endothelial cells (HUVECs). After irradiation by a 660 nm infrared laser for 72 h, the survival rate of 4T1 cells was 15.51%. Cellular uptake studies indicated that the NPs could accurately release drugs into tumor cells. In addition, the NPs had a good photodynamic effect and promoted the release of reactive oxygen species to damage tumor cells. Overall, the combination therapy of IPI-549 and Ce6 is safe and effective, and may provide a new avenue for the treatment of breast cancer.

Research Progress of Carrier-Free Antitumor Nanoparticles Based on Phytochemicals

Cancer is a major worldwide public health issue, responsible for millions of deaths every year. Cancer cases and deaths are expected to increase rapidly with population growth, age, and lifestyle behaviors that increase cancer risk. Long-term chemotherapy results in acquired drug resistance. Traditional treatment methods have limitations and cannot effectively treat distal metastatic cancers. Application of nanocarriers in multi-chemotherapy must be promoted. With research progress, the shortcomings of traditional nanocarriers have gradually become evident. Carrier-free nanodrugs with desirable bioactivity have attracted considerable attention. In this review, we provide an overview of recent reports on several carrier-free nanodrug delivery systems based on phytochemicals. This review focuses on the advantages of carrier-free nanodrugs, and provides new insights for establishment of ideal cancer treatment nanosystems.

A nanosensitizer self-assembled from oleanolic acid and chlorin e6 for synergistic chemo/sono-photodynamic cancer therapy

BACKGROUND

Sono-photodynamic therapy (SPDT) which is the combination of photodynamic therapy (PDT) and sonodynamic therapy (SDT), could exert much better anti-cancer effects than monotherapy. The combination of chemotherapy and PDT or SDT has shown great potential for cancer treatment. However, the combination of SPDT and chemotherapy for cancer treatment is rarely explored.

PURPOSE

We utilized a natural hydrophobic anti-cancer drug oleanolic acid (OA) and a photosensitizer chlorin e6 (Ce6) through self-assembly technology to form a carrier-free nanosensitizer OC for combined chemotherapy and SPDT for cancer treatment. No studies involving using carrier-free nanomedicine for combined chemotherapy/SPDT have been reported yet.

STUDY DESIGN

After fully characterization of OC, the in vitro and in vivo anti-cancer activities of OC were investigated and the mechanisms of the synergistic therapeutic effects were studied.

METHODS

OC were synthesized through self-assembly technology and characterized by dynamic light scattering (DLS) and an atomic force microscope (AFM). Confocal microscope was used to investigate the intracellular uptake efficiency and the penetration ability of OC. The cell viability of PC9 and 4T1 cells treated with OC under laser and ultrasound (US) irradiation was determined by MTT assay. Furthermore, flow cytometry was performed to detect the reactive oxygen species (ROS) generation, loss of mitochondrial membrane potential (MMP), cell apoptosis and cell cycle arrest. Finally, the anti-tumor therapeutic efficacy of OC was investigated in orthotopic 4T1 breast tumor-bearing mouse model.

RESULTS

OC showed an average particle size of around 100 nm with excellent light stability. OC increased more than 23 times accumulation of Ce6 in cancer cells and had strong tumor penetration ability in three-dimensional (3D) multicellular tumor spheroids (MCTSs). Compared with other therapeutic options, OC showed obvious synergistic inhibitory effects under light and US irradiation in PC9 and 4T1 cells with a significant decrease in IC₅₀ values. Mechanism studies showed that OC could generate high ROS, induce MMP loss, and cause apoptosis and cell cycle arrest. In vivo studies also approved the synergistic therapeutic effects of OC in 4T1 mouse models.

CONCLUSION

Self-assembled carrier-free nanosensitizer OC could be a promising therapeutic agent for synergistic chemo/sono-photodynamic therapy for cancer treatment.

Delivering more for less: nanosized, minimal-carrier and pharmacoactive drug delivery systems

Traditional nanoparticle carriers such as liposomes, micelles, and polymeric vehicles improve drug delivery by protecting, stabilizing, and increasing the circulatory half-life of the encapsulated drugs. However, traditional drug delivery systems frequently suffer from poor drug loading and require an excess of carrier materials. This carrier material excess poses an additional systemic burden through accumulation, if not degradable the need for metabolism, and potential toxicity. To address these shortcomings, minimal-carrier nanoparticle systems and pharmacoactive carrier materials have been developed. Both solutions provide drug delivery systems in which the majority of the nanoparticle is pharmacologically active. While minimal-carrier and pharmacoactive drug delivery systems can improve drug loading, they can also suffer from poor stability. Here, we review minimal-carrier and pharmacoactive delivery systems, discuss ongoing challenges and outline opportunities to translate minimal-carrier and pharmacoactive drug delivery systems into the clinic.

The role of photodynamic therapy in breast cancer - A review of in vitro research

Breast cancer is the most common cancer affecting women and the incidence of occurrence is increasing. Currently, there are many methods of detecting and treating breast cancer. Some treatments have a number of side effects. Photodynamic therapy (PDT) is a minimally invasive method of treatment which uses monochromatic light of low to medium energy to excite previously applied photosensitizers (PS) for ROS production. The purpose of this article is to present a general overview of the use of PDT in in vitro studies of various cancer cell lines. A literature search for articles corresponding to the topic of this review was performed using the PubMed and Scopus databases using the following keywords: 'photodynamic therapy', 'breast cancer', and 'photosensitizer(s).' Much of the reviewed literature is based on evaluations of the cytotoxic potential of various PSs, particularly against the MCF-7 cell line, and enhancement of PDT potential with nanotechnology. Research on photodynamic effects in vitro may be helpful in the pre-clinical search for optimal methods for in vivo clinical treatment.

A carrier-free nanoparticle with dual NIR/acid responsiveness by co-assembly of enediyne and IR820 for combined PTT/chemotherapy

Combined photothermal therapy/chemotherapy by co-delivery of a photosensitizer (PS) and a chemotherapeutic drug has demonstrated great potential for cancer treatment. The intrinsic drawbacks of traditional drug delivery systems (DDSs), such as tedious synthetic procedures, side effects originated from the carrier materials, low loading efficiency, and uncontrolled drug release, however, have impaired their further advancement. On the other hand, enediyne antibiotics are highly cytotoxic toward cancer cells through the generation of lethal carbon radicals via thermal-induced cyclization, endowing them with great potential to achieve enhanced synergistic anticancer performance by incorporation with the photothermal effect of PS. To this end, a carrier-free and NIR/acid dual-responsive DDS was constructed for combined photothermal therapy/chemotherapy. The facile co-assembly of maleimide-based enediyne and PS IR820 was achieved in aqueous solution to give nanoparticles (EICN) with a hydrodynamic diameter of 90 nm and high stability. In vitro study confirmed the acid/NIR dual-responsive degradation and drug release, free radical generation and DNA-cleaving ability of EICN, which was accomplished by the corporation of enediyne and IR820 moieties. Further tests on HeLa cells verified the excellent synergistic anticancer performance of EICN including the improved cellular uptake, NIR-enhanced drug release, DNA damage and histone deacetylase inhibitor capacity. Overall, this carrier-free DDS with dual acid/NIR-responsivity would potentially provide new insights for the development of combined photothermal/chemotherapy.

Particle engineering principles and technologies for pharmaceutical biologics

The global market of pharmaceutical biologics has expanded significantly during the last few decades. Currently, pharmaceutical biologic products constitute an indispensable part of the modern medicines. Most pharmaceutical biologic products are injections either in the forms of solutions or lyophilized powders because of their low oral bioavailability. There are certain pharmaceutical biologic entities formulated into particulate delivery systems for the administration via non-invasive routes or to achieve prolonged pharmaceutical actions to reduce the frequency of injections. It has been well documented that the design of nano- and microparticles via various particle engineering technologies could render pharmaceutical biologics with certain benefits including improved stability, enhanced intracellular uptake, prolonged pharmacological effect, enhanced bioavailability, reduced side effects, and improved patient compliance. Herein, we review the principles of the particle engineering technologies based on bottom-up approach and present the important formulation and process parameters that influence the critical quality attributes with some mathematical models. Subsequently, various nano- and microparticle engineering technologies used to formulate or process pharmaceutical biologic entities are reviewed. Lastly, an array of commercialized products of pharmaceutical biologics accomplished based on various particle engineering technologies are presented and the challenges in the development of particulate delivery systems for pharmaceutical biologics are discussed.

Carrier-free nanodrugs for safe and effective cancer treatment

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

Bioactive Natural Small Molecule-Tuned Coassembly of Photosensitive Drugs for Highly Efficient Synergistic and Enhanced Type I Photochemotherapy

Self-assembling natural small molecules (NSMs) with favorable anticancer activity are of increasing interest as novel drug delivery platforms without structural modification for biomedical applications. However, a lack of knowledge and practicability of NSMs as drug carriers limited their current biomedical application. Here, via a green and facile supramolecular coassembly strategy, we report and develop a series of carrier-free terpenoid natural small molecule-mediated coassembled photosensitive drugs for enhanced and synergistic chemo/photodynamic therapy. After screening 17 terpenoid NSMs, we identified 11 compounds that could form coassembled NSMs-Ce6 NPs with regulatable drug sizes. Analysis of the representative betulonic acid (BC)-mediated nano-coassemblies (BC-Ce6 NPs) reveals the high efficiency of the coassembly strategy and highlights the tremendous potential of NSMs as novel drug delivery platforms. Through molecular dynamics simulation and theoretical calculations, we elucidate the mystery of the coassembly process, indicating that the linear coplanar arrangement of BC dimeric units is primarily responsible for the formation of rod-like or spherical morphology. Meanwhile, we demonstrated that the reduced energy gap between the singlet and triplet excited states (ΔE_ST) facilitates efficient reactive oxygen species generation by promoting ·OH generation via a type I photoreaction mechanism. The assembled nanodrugs exhibit multiple favorable therapeutic features, ensuring a remarkably enhanced, synergistic, and secure combinatorial anticancer efficacy of 93.6% with highly efficient tumor ablation. This work not only expands the possibility of natural biodegradable materials for wide biological applications but also provides a new perspective for the construction of NSM-mediated nano-coassemblies for precision therapy.

Supramolecular self-assembled drug delivery system (SADDs) of vancomycin and tocopherol succinate as an antibacterial agent: in vitro, in silico and in vivo evaluations

In this study self-assembled drug delivery system (SADDs) composed of a hydrophobic d-α-tocopherol succinate (TS) and a hydrophilic vancomycin (VCM) were formulated, and its potential for enhancing the antibacterial activity of VCM against Staphylococcus aureus (SA) and Methicillin-resistant Staphylococcus aureus (MRSA) were explored. The SADDs were synthesized via supramolecular complexation, then characterized for in silico, in vitro and in vivo studies. In silico studies confirmed the self-assembly of VCM/TS into NPs. The size, surface charge and drug loading of the SADDs was ˂100 nm, -27 mV and 68%, respectively. The SADDs were non-hemolytic and biosafe. A sustained release of VCM from SADDs was noted, with 52.2% release after 48 hr. The in vitro antibacterial test showed a twofold decrease in Minimum inhibitory concentration (MIC) against SA and MRSA, and a significantly higher reduction in MRSA biofilms compared to bare VCM. Further, in silico studies confirmed strong and stable binding of TS to MRSA efflux pumps. The in vivo study using mice skin infection models showed a 9.5-fold reduction in bacterial load after treatment with SADDs, in comparison with bare VCM. These findings affirmed that VCM/TS NPs as a promising novel nano-delivery for treating bacterial infections.