Enzyme-Responsive Amphiphilic Peptide Nanoparticles for Biocompatible and Efficient Drug Delivery

Folic Acid-Targeted Mixed Pluronic Micelles for Delivery of Triptolide

The present study aimed to explore an ideal delivery system for triptolide (TPL) by utilizing the thin-film hydration method to prepare drug-loaded, folate-modified mixed pluronic micelles (FA-F-127/F-68-TPL). Scanning electron microscopy and atomic force microscopy showed that the drug-loaded micelles had a spherical shape with a small particle size, with an average of 30.7 nm. Cell viability experiments showed that FA-F-127/F-68-TPL significantly reduced HepG2 cell viability, exhibiting strong cytotoxicity. Its cytotoxicity was markedly enhanced compared with bare TPL. Nile red (Nr) was used as a model drug to prepare FA-F-127/F-68-Nr to further validate its tumor-targeting and cellular uptake capability. After coincubation with HepG2 cells, a multifunctional microplate reader showed that intracellular fluorescence intensity significantly increased, indicating that FA-F-127/F-68-Nr could more effectively enter the cells. A nude mouse model of subcutaneous hepatocellular carcinoma was constructed. Following tail vein injection of FA-F-127/F-68-Nr, the fluorescence imaging system showed that FA-F127/F-68-Nr could significantly target tumor tissue, and even if entering the small-sized tumor was challenging, it could be excreted through urine. Nude mice with subcutaneous hepatocellular carcinoma were treated with tail vein injections of FA-F-127/F-68-TPL (45 µg/kg) every other day for 21 days. The results showed that the growth of the transplanted tumors was significantly slowed, with no significant difference compared with bare TPL. In summary, the FA-F-127/F-68-TPL exhibits the advantages of low cost, excellent biological properties, active/passive targeting capabilities, notable cytotoxicity against liver cancer cells, and significant inhibition of transplanted hepatocellular carcinoma growth. Significantly, the FA-F-127/F-68-TPL, despite challenges in targeting tumors with an insignificant EPR effect, can be efficiently excreted via the kidneys, thereby preventing the release of the drug during prolonged circulation and potential damage to normal tissues. Therefore, FA-F-127/F-68-TPL represents a promising antitumor drug delivery system.

Integrin-Specific Stimuli-Responsive Nanomaterials for Cancer Theranostics

Background: Cancer is one of the leading causes of death worldwide. The tumor microenvironment makes the tumor difficult to treat, favoring drug resistance and the formation of metastases, resulting in death. Methods: Stimuli-responsive nanoparticles have shown great capacity to be used as a powerful strategy for cancer treatment, diagnostic, as well as theranostic. Nanocarriers are not only able to respond to internal stimuli such as oxidative stress, weakly acidic pH, high temperature, and the high expression of particular enzymes, but also to external stimuli such as light and paramagnetic characteristics to be exploited. Results: In this work, stimulus-responsive nanocarriers functionalized with arginine-glycine-aspartic acid (Arg-Gly-Asp) sequence as well as mimetic sequences with the capability to recognize integrin receptors are analyzed. Conclusions: This review highlights the progress that has been made in the development of new nanocarriers, capable of responding to endogenous and exogenous stimuli essential to combat cancer.

Release kinetics and protective effect of novel curcumin-based nanoliposome modified with pectin, whey protein isolates and hyaluronic acid against oxidative stress

In the present study, a novel nanoliposome loaded with curcumin (Cur) (NNLs-Cur) was established to overcome the gastrointestinal digestive barrier and enhance mitochondrial targeting capacity, exerting the antioxidant capacity of Cur. Noteworthy, NNLs-Cur was modified by pectin, whey protein isolates and hyaluronic acid. The results showed that the structure of traditional nanoliposomes loaded with Cur (NLs-Cur) was destroyed during digestion. However, NNLs-Cur maintained intact structural morphology, and the release of Cur in the stomach and intestines was consistent with zero-order and first-order kinetic models, respectively. Interestingly, the survival rate of HL-7702 cells after being damaged by H2O2 was 40.53 %, while the survival rate after treated with NNLs-Cur reached 99.87 %. Besides, the fluorescence localization indicated Cur in NNLs-Cur could escape lysosomal and achieve mitochondria targeting. Compared with NLs-Cur, the damaged cells treated with NNLs-Cur increased activities of catalase (CAT), glutathione peroxide (GSH-Px) and superoxide dismutase (SOD) from 16.16 ± 0.52, 16.92 ± 2.28 and 30.10 ± 0.93 U/mgprot to 19.09 ± 0.52, 20.41 ± 1.79 and 33.81 ± 0.29 U/mgprot, respectively. Malondialdehyde (MDA) content and reactive oxygen species (ROS) level of the oxidative damaged cells were reduced, mitochondrial membrane potential was restored, and cell apoptosis was reduced. This study provides theoretical guidance for realizing the industrial application of efficient targeted delivery Cur.

Design and evaluation of nanoscale materials with programmed responsivity towards epigenetic enzymes

Self-assembled materials capable of modulating their assembly properties in response to specific enzymes play a pivotal role in advancing 'intelligent' encapsulation platforms for biotechnological applications. Here, we introduce a previously unreported class of synthetic nanomaterials that programmatically interact with histone deacetylase (HDAC) as the triggering stimulus for disassembly. These nanomaterials consist of co-polypeptides comprising poly(acetyl L-lysine) and poly(ethylene glycol) blocks. Under neutral pH conditions, they self-assemble into particles. The hydrodynamic diameters of particles were typically withing the range of 108-190 nm, depending on degree of acetylation of the hydrophobic block. However, their stability is compromised upon exposure to HDACs, depending on enzyme concentration and exposure time. Our investigation, utilizing HDAC8 as the model enzyme, revealed that the primary mechanism behind disassembly involves a decrease in amphiphilicity within the block copolymer due to the deacetylation of lysine residues within the particles' hydrophobic domains. To elucidate the response mechanism, we encapsulated a fluorescent dye within these nanoparticles. Upon incubation with HDAC, the nanoparticle structure collapsed, leading to controlled release of the dye over time. Notably, this release was not triggered by denatured HDAC8, other proteolytic enzymes like trypsin, or the co-presence of HDAC8 and its inhibitor. We also demonstrated the biocompatibility and cellular effects of these materials in the context of drug delivery in different types of anticancer cell lines, such as MIA PaCa-2, PANC-1, cancer like stem cells (CSCs), and non-cancerous HPNE cells. We observed that the release of a model drug (such as a STAT3 pathway inhibitor, Napabucasin) can be loaded into these nanoparticles, with >90% of the dosage can be released over 3 h under the influence of HDAC8 enzyme in a controlled fashion. Further, we conducted a comprehensive computational study to unveil the possible interaction mechanism between enzymes and particles. By drawing parallels to the mechanism of naturally occurring histone proteins, this research represents a pioneering step toward developing functional materials capable of harnessing the activity of epigenetic enzymes such as HDACs.

Surface Modification of Mesoporous Silica Nanoparticles for Application in Targeted Delivery Systems of Antitumour Drugs

The problem of tumour therapy has attracted the attention of many researchers for many decades. One of the promising strategies for the development of new dosage forms to improve oncology treatment efficacy and minimise side effects is the development of nanoparticle-based targeted transport systems for anticancer drugs. Among inorganic nanoparticles, mesoporous silica deserves special attention due to its outstanding surface properties and drug-loading capability. This review analyses the various factors affecting the cytotoxicity, cellular uptake, and biocompatibility of mesoporous silica nanoparticles (MSNs), constituting a key aspect in the development of safe and effective drug delivery systems. Special attention is paid to technological approaches to chemically modifying MSNs to alter their surface properties. The stimuli that regulate drug release from nanoparticles are also discussed, contributing to the effective control of the delivery process in the body. The findings emphasise the importance of modifying MSNs with different surface functional groups, bio-recognisable molecules, and polymers for their potential use in anticancer drug delivery systems.

Design and Evaluation of Nanoscale Materials with Programmed Responsivity towards Epigenetic Enzymes

Self-assembled materials capable of modulating their assembly properties in response to specific enzymes play a pivotal role in advancing 'intelligent' encapsulation platforms for biotechnological applications. Here, we introduce a previously unreported class of synthetic nanomaterials that programmatically interact with histone deacetylase (HDAC) as the triggering stimulus for disassembly. These nanomaterials consist of co-polypeptides comprising poly (acetyl L-lysine) and poly(ethylene glycol) blocks. Under neutral pH conditions, they self-assemble into particles. However, their stability is compromised upon exposure to HDACs, depending on enzyme concentration and exposure time. Our investigation, utilizing HDAC8 as the model enzyme, revealed that the primary mechanism behind disassembly involves a decrease in amphiphilicity within the block copolymer due to the deacetylation of lysine residues within the particles' hydrophobic domains. To elucidate the response mechanism, we encapsulated a fluorescent dye within these nanoparticles. Upon incubation with HDAC, the nanoparticle structure collapsed, leading to controlled release of the dye over time. Notably, this release was not triggered by denatured HDAC8, other proteolytic enzymes like trypsin, or the co-presence of HDAC8 and its inhibitor. We further demonstrated the biocompatibility and cellular effects of these materials and conducted a comprehensive computational study to unveil the possible interaction mechanism between enzymes and particles. By drawing parallels to the mechanism of naturally occurring histone proteins, this research represents a pioneering step toward developing functional materials capable of harnessing the activity of epigenetic enzymes such as HDACs.

Progress of stimulus responsive nanosystems for targeting treatment of bacterial infectious diseases

In recent decades, due to insufficient concentration at the lesion site, low bioavailability and increasingly serious resistance, antibiotics have become less and less dominant in the treatment of bacterial infectious diseases. It promotes the development of efficient drug delivery systems, and is expected to achieve high absorption, targeted drug release and satisfactory therapy effects. A variety of endogenous stimulation-responsive nanosystems have been constructed by using special infection microenvironments (pH, enzymes, temperature, etc.). In this review, we firstly provide an extensive review of the current research progress in antibiotic treatment dilemmas and drug delivery systems. Then, the mechanism of microenvironment characteristics of bacterial infected lesions was elucidated to provide a strong theoretical basis for bacteria-targeting nanosystems design. In particular, the discussion focuses on the design principles of single-stimulus and dual-stimulus responsive nanosystems, as well as the use of endogenous stimulus-responsive nanosystems to deliver antimicrobial agents to target locations for combating bacterial infectious diseases. Finally, the challenges and prospects of endogenous stimulus-responsive nanosystems were summarized.

Evaluation of glycyl-arginine and lysyl-aspartic acid dipeptides for their antimicrobial, antibiofilm, and anticancer potentials

Antibacterial resistance and cancer are worldwide challenges and have been defined as major threats by international health organizations. Peptides are produced naturally by all organisms and have a variety of immunomodulatory, physiological, and wound-healing properties. They can also provide protection against microorganisms and tumor cells. Therefore, we aimed to determine the antimicrobial, antibiofilm, and anticancer potentials of Glycyl-Arginine and Lysyl-Aspartic acid dipeptides. The Broth Dilution and Crystal Violet Binding assays assessed the antimicrobial tests and biofilm inhibitory effects. The MTT assay was used to measure the cytotoxic effects of dipeptides on HeLa cell viability. According to our results, Candida tropicalis T26 and Proteus mirabilis U15 strains were determined as more resistant to Staphylococcus epidermidis W17 against Glycyl-Arginine and Lysyl-Aspartic acid dipeptides with MICs higher than 2 mM (1 mg/mL). Sub-MICs of Glycyl-Arginine caused inhibitions against biofilm formation of all the tested clinical isolates, with the highest inhibition observed against S. epidermidisW17. Lysyl-Aspartic acid exhibited zero to no effect against biofilm formation of P. mirabilisU15, and S. epidermidisW17, whereas it exhibited 52% inhibition of biofilm formation of C. tropicalisT26. Cell viability results revealed that HeLa cell viability decreases with increasing concentration of both dipeptides. Also, parallel to antimicrobial tests, Glycyl-Arginine has a greater cytotoxic effect compared to Lysyl-Aspartic acid. The findings from this study will contribute to the advancement of novel strategies involving dipeptide-based synthesizable molecules and drug development studies. However, it is essential to note that there are still challenges, including the need for extensive experimental and clinical trials.

Intracellular spatiotemporal metabolism in connection to target engagement

The metabolism in eukaryotic cells is a highly ordered system involving various cellular compartments, which fluctuates based on physiological rhythms. Organelles, as the smallest independent sub-cell unit, are important contributors to cell metabolism and drug metabolism, collectively designated intracellular metabolism. However, disruption of intracellular spatiotemporal metabolism can lead to disease development and progression, as well as drug treatment interference. In this review, we systematically discuss spatiotemporal metabolism in cells and cell subpopulations. In particular, we focused on metabolism compartmentalization and physiological rhythms, including the variation and regulation of metabolic enzymes, metabolic pathways, and metabolites. Additionally, the intricate relationship among intracellular spatiotemporal metabolism, metabolism-related diseases, and drug therapy/toxicity has been discussed. Finally, approaches and strategies for intracellular spatiotemporal metabolism analysis and potential target identification are introduced, along with examples of potential new drug design based on this.

Research progress of nanoparticle targeting delivery systems in bacterial infections

Bacterial infection is a huge threat to the health of human beings and animals. The abuse of antibiotics have led to the occurrence of bacterial multidrug resistance, which have become a difficult problem in the treatment of clinical infections. Given the outstanding advantages of nanodrug delivery systems in cancer treatment, many scholars have begun to pay attention to their application in bacterial infections. However, due to the similarity of the microenvironment between bacterial infection lesions and cancer sites, the targeting and accuracy of traditional microenvironment-responsive nanocarriers are questionable. Therefore, finding new specific targets has become a new development direction of nanocarriers in bacterial prevention and treatment. This article reviews the infectious microenvironment induced by bacteria and a series of virulence factors of common pathogenic bacteria and their physiological functions, which may be used as potential targets to improve the targeting accuracy of nanocarriers in lesions.

Development of a Peptide-Based Nano-Sized Cathepsin B Inhibitor for Anticancer Therapy

Numerous cathepsin B inhibitors have been developed and are under investigation as potential cancer treatments. They have been evaluated for their ability to inhibit cathepsin B activity and reduce tumor growth. However, they have shown critical limitations, including low anticancer efficacy and high toxicity, due to their low selectivity and delivery problems. In this study, we developed a novel peptide and drug conjugate (PDC)-based cathepsin B inhibitor using cathepsin-B-specific peptide (RR) and bile acid (BA). Interestingly, this RR and BA conjugate (RR–BA) was able to self-assemble in an aqueous solution, and as a result, it formed stable nanoparticles. The nano-sized RR–BA conjugate showed significant cathepsin B inhibitory effects and anticancer effects against mouse colorectal cancer (CT26) cells. Its therapeutic effect and low toxicity were also confirmed in CT26 tumor-bearing mice after intravenous injection. Therefore, based on these results, the RR–BA conjugate could be developed as an effective anticancer drug candidate for inhibiting cathepsin B in anticancer therapy.

A cathepsin B/GSH dual-responsive fluorinated peptide for effective siRNA delivery to cancer cells

Small interfering RNA (siRNA) can be exploited to silence specific genes associated with cancer development, and successful siRNA therapy is highly dependent on the efficiency of the siRNA delivery vector. Herein, a well-designed novel redox- and enzyme-responsive fluorinated polyarginine (PFC-PR) was developed to be used as an anti-cancer siRNA carrier. The multiple guanidine groups could provide positive charges and bind with siRNA efficiently, and further fluorination modification enhanced the interaction with siRNA, resulting in a more stable PFC-PR/siRNA nanocomplex, improving serum tolerance, and promoting cellular uptake and endosome escape. Meanwhile, the PFC-PR was responsive to overexpressed cathepsin B and high levels of glutathione in cancer cells, conferring its ability to enhance siRNA release within cancer cells and making it cancer-targeting. Consequently, PFC-PR showed good biocompatibility and high gene silencing efficiency, which could inhibit cancer cell growth when delivered the siRNA targeting vascular endothelial growth factor, suggesting that it can be potentially used for anti-cancer gene therapy applications.

Recent Advances in Stimuli-Responsive Doxorubicin Delivery Systems for Liver Cancer Therapy

Doxorubicin (DOX) is one of the most commonly used drugs in liver cancer. Unfortunately, the traditional chemotherapy with DOX presents many limitations, such as a systematic release of DOX, affecting both tumor tissue and healthy tissue, leading to the apparition of many side effects, multidrug resistance (MDR), and poor water solubility. Furthermore, drug delivery systems' responsiveness has been intensively studied according to the influence of different internal and external stimuli on the efficiency of therapeutic drugs. In this review, we discuss both internal stimuli-responsive drug-delivery systems, such as redox, pH and temperature variation, and external stimuli-responsive drug-delivery systems, such as the application of magnetic, photo-thermal, and electrical stimuli, for the controlled release of Doxorubicin in liver cancer therapy, along with the future perspectives of these smart delivery systems in liver cancer therapy.

Cysteine-phenylalanine-derived self-assembled nanoparticles as glutathione-responsive drug-delivery systems in yeast

Despite the availability of different antifungal drugs in the market, their overall usefulness remains questionable due to the relatively high toxic profiles exerted by them in many cases. In addition, the emergence of drug resistance against these antifungal agents is a matter of concern. Thus, it becomes imperative to explore innovative drug-delivery vehicles to deliver these antifungal drugs for enhanced efficacy, mitigating unwanted side effects and tackling the surge in antifungal resistance. Considering this fact, in this piece of work, we have synthesized stimulus (glutathione)-responsive dipeptide-based self-assembled nanoparticles (NPs) to explore and establish the redox-responsive antifungal drug delivery of a relatively hydrophobic drug, terbinafine (Terb), in Saccharomyces cerevisiae (S. cerevisiae). The NPs were prepared using a relatively aqueous environment as opposed to other Terb formulations that are administered in mostly non-polar solvents and with limited biocompatibility. The NPs demonstrated an encapsulation efficiency of around 99% for Terb and resulted in complete inhibition of yeast-cell growth at a dose of 200 μg mL^-1 of the drug-loaded formulation. Thus, these biocompatible and aqueous dipeptide-based redox-responsive NPs can offer a promising drug-delivery platform to provide enhanced antifungal drug delivery with heightened efficacy and biocompatibility.

Tumor Microenvironment-Based Stimuli-Responsive Nanoparticles for Controlled Release of Drugs in Cancer Therapy

With the development of nanomedicine technology, stimuli-responsive nanocarriers play an increasingly important role in antitumor therapy. Compared with the normal physiological environment, the tumor microenvironment (TME) possesses several unique properties, including acidity, high glutathione (GSH) concentration, hypoxia, over-expressed enzymes and excessive reactive oxygen species (ROS), which are closely related to the occurrence and development of tumors. However, on the other hand, these properties could also be harnessed for smart drug delivery systems to release drugs specifically in tumor tissues. Stimuli-responsive nanoparticles (srNPs) can maintain stability at physiological conditions, while they could be triggered rapidly to release drugs by specific stimuli to prolong blood circulation and enhance cancer cellular uptake, thus achieving excellent therapeutic performance and improved biosafety. This review focuses on the design of srNPs based on several stimuli in the TME for the delivery of antitumor drugs. In addition, the challenges and prospects for the development of srNPs are discussed, which can possibly inspire researchers to develop srNPs for clinical applications in the future.

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.