pH-Responsive Drug-Delivery Systems

Advances in cellulose-based hydrogels: tunable swelling dynamics and their versatile real-time applications

Cellulose-derived hydrogels have emerged as game-changing materials in biomedical research, offering an exceptional combination of water absorption capacity, mechanical resilience, and innate biocompatibility. This review explores the intricate mechanisms that drive their swelling behaviour, unravelling how molecular interactions and network architectures work synergistically to enable efficient water retention and adaptability. Their mechanical properties are explored in depth, with a focus on innovative chemical modifications and cross-linking techniques that enhance strength, elasticity, and functional versatility. The versatility of cellulose-based hydrogels shines in applications such as wound healing, precision drug delivery, and tissue engineering, where their biodegradability, biocompatibility, and adaptability meet the demands of cutting-edge healthcare solutions. By weaving together recent breakthroughs in their development and application, this review highlights their transformative potential to redefine regenerative medicine and other biomedical fields. Ultimately, it emphasizes the urgent need for continued research to unlock the untapped capabilities of these extraordinary biomaterials, paving the way for new frontiers in healthcare innovation.

Responsive Zwitterionic Materials for Enhanced Drug Delivery

Zwitterionic materials have traditionally been recognized as exceptional antifouling agents, imparting nanocarriers with extended circulation times in vivo. Despite much studies on antifouling ability, the responsive zwitterionic materials that change physicochemical properties stimulated by mild signals are much less explored. As is known, there are multiple biological barriers in antitumor drug delivery, including the blood circulation barrier, non-specific organ distribution, elevated tumor interstitial pressure, tumor cytomembrane barrier, and lysosomal barrier. Multiple biological barriers restrict the delivery efficiency of nanocarriers to tumors, leading to a reduced therapeutic effect and increased side effects. Therefore, it is far from satisfactory to overcome the blood circulation barrier alone for classical zwitterionic antitumor materials. To address this challenge, recently developed responsive zwitterionic materials have been engineered to overcome multiple biological barriers, thereby enabling more effective antitumor drug delivery. Furthermore, responsive zwitterionic materials could respond to signals by themselves without the need of incorporating extra stimuli-responsive groups, which maintains the simplicity of the molecular structure. In this mini-review, the recent progress of antitumor zwitterionic materials responding to pH, temperature, enzyme, or reactive oxygen species is summarized. Furthermore, prospects and challenges of responsive zwitterionic materials are provided to promote better development of this field.

Intelligent Drug Delivery: Pioneering Stimuli-Responsive Systems to Revolutionize Disease Management- An In-depth Exploration

In recent years, there has been an escalating interest in stimuli-responsive drug delivery systems (SRDDS) due to their ability to revolutionize the delivery of therapeutics. SRDDSs offer a multitude of benefits in comparison to conventional drug delivery systems (DDS), including spatiotemporal control of drug release, targeted delivery, and improved therapeutic efficacy. The development of various classes of stimuli-responsive DDS, such as pH-responsive, temperature-responsive, photo-responsive, redox responsive systems, has been propelled by advances in materials science, nanotechnology, and biotechnology. These systems exploit specific environmental or physiological cues to trigger drug release in a precisely controlled manner, making them highly promising for the treatment of various diseases. In this review article, an in-depth exploration of the principles, mechanisms, and applications of SRDDS in the context of diverse pathologies such as cancer, arthritis, Alzheimer's disease, atherosclerosis and tissue engineering has been provided. Furthermore, this article delves into the discussion of recent patents, market overview and the progress of research in clinical trials. Overall, this article underscores the transformative potential of SRDDS in enabling personalized, precise, and effective drug delivery for the treatment of the above-mentioned diseases.

A pH-responsive dual-network biopolysaccharide hydrogel with enhanced self-healing and controlled drug release properties

Traditional hydrogels based on Schiff base reactions frequently encounter issues with rapid drug release when employed as drug delivery systems owing to their susceptibility to hydrolysis under acidic conditions. It is, therefore, necessary to implement improvements to regulate the drug release behavior. In this study, a dual-network and pH-responsive biopolysaccharide hydrogel was developed, which is self-healing, injectable and biocompatible. Most importantly, the hydrogel has excellent tunability for controlled drug release. The hydrogel consisted of a primary network of dibenzaldehyde-functionalized poly(ethylene glycol) (DP) and chitosan (CS) formed through a Schiff base reaction and a secondary network of sodium alginate (SA) and CS formed through electrostatic interactions. It was found that the DP-CS-2%SA hydrogel can prolong the release duration up to four-fold compared to the single-network DP-CS hydrogel at a given release threshold. Significantly, by adjusting the relationship between the two effects through the amount of SA, the release modifiability of drug delivery systems has been greatly enhanced. This study could significantly enhance the tunability of hydrogel drug delivery systems.

pH factors in chronic wound and pH-responsive polysaccharide-based hydrogel dressings

Chronic wounds present a significant healthcare challenge marked by complexities such as persistent bleeding, inhibited cell proliferation, dysregulated inflammation, vulnerability to infection, and compromised tissue remodeling. Conventional wound dressings often prove inadequate in addressing the intricate requirements of chronic wound healing, leading to slow healing and heightened susceptibility to infections in patients with prolonged medical conditions. Bacterial biofilms in chronic wounds pose an additional challenge due to drug resistance. Advanced wound dressings have emerged as promising tools in expediting the healing process. Among these, pH-responsive polysaccharide-based hydrogels exhibit immense prospect by adapting their functions to dynamic wound conditions. Despite their potential, the current literature lacks a thorough review of these wound dressings. This review bridges this gap by meticulously examining factors related to chronic wounds, current strategies for healing, and the mechanisms and potential applications of pH-responsive hydrogel wound dressings as an emerging therapeutic solution. Special focus is given to their remarkable antibacterial properties and significant self-healing abilities. It further explores the pH-monitoring functions of these dressings, elucidating the associated pH indicators. This synthesis of knowledge aims to guide future research and development in the field of pH-responsive wound dressings, providing valuable insights into their potential applications in wound care.

Acid-sensitive prodrugs; a promising approach for site-specific and targeted drug release

Drugs administered through conventional formulations are devoid of targeting and often spread to various undesired sites, leading to sub-lethal concentrations at the site of action and the emergence of undesired effects. Hence, therapeutic agents should be delivered in a controlled manner at target sites. Currently, stimuli-based drug delivery systems have demonstrated a remarkable potential for the site-specific delivery of therapeutic moieties. pH is one of the widely exploited stimuli for drug delivery as several pathogenic conditions such as tumor cells, infectious and inflammatory sites are characterized by a low pH environment. This review article aims to demonstrate various strategies employed in the design of acid-sensitive prodrugs, providing an overview of commercially available acid-sensitive prodrugs. Furthermore, we have compiled the progress made for the development of new acid-sensitive prodrugs currently undergoing clinical trials. These prodrugs include albumin-binding prodrugs (Aldoxorubicin and DK049), polymeric micelle (NC-6300), polymer conjugates (ProLindac™), and an immunoconjugate (IMMU-110). The article encompasses a broad spectrum of studies focused on the development of acid-sensitive prodrugs for anticancer, antibacterial, and anti-inflammatory agents. Finally, the challenges associated with the acid-sensitive prodrug strategy are discussed, along with future directions.

Revealing the pH-dependent conformational changes in sol g 2.1 protein and potential ligands binding

Sol g 2, a major protein found in the venom of the tropical fire ant (Solenopsis geminata), is well-known for its ability to bind various hydrophobic molecules. In this study, we investigate the binding activity of recombinant Sol g 2.1 protein (rSol g 2.1) with potential molecules, including (E)-β-Farnesene, α-Caryophyllene, and 1-Octen-3-ol at different pH levels (pH 7.4 and 5.5) using fluorescence competitive binding assays (FCBA). Our results revealed that Sol g 2.1 protein has higher affinity binding with these ligands at neutral pH. Relevance to molecular docking and molecular dynamics simulations were utilized to provide insights into the stability and conformational dynamics of Sol g 2.1 and its ligand complexes. After simulation, we found that Sol g 2.1 protein has higher affinity binding with these ligands as well as high structural stability at pH 7.4 than at an acidic pH level, indicating by RMSD, RMSF, Rg, SASA, and principal component analysis (PCA). Additionally, the Sol g 2.1 protein complexes at pH 7.4 showed significantly lower binding free energy (∆Gbind) and higher total residue contributions, particularly from key non-polar amino acids such as Trp36, Met40, Cys62, and Ile104, compared to the lower pH environment. These explain why they exhibited higher binding affinity than the lower pH. Therefore, we suggested that Sol g 2.1 protein is a pH-responsive carrier protein. These findings also expand our understanding of protein-ligand interactions and offer potential avenues for the development of innovative drug delivery strategies targeting Sol g 2.1 protein.

Entropy-favorable adsorption of polymer-grafted nanoparticles at fluid-fluid interfaces

The adsorption of polymer-grafted nanoparticles at interfaces is a problem of fundamental interest in physics and soft materials. This adsorption behavior is governed by the interplay between interaction potentials and entropic effects. Here, we use molecular dynamics simulations and umbrella sampling methods to study the adsorption behavior of a Janus-like homopolymer-grafted nanoparticle at fluid-fluid interfaces. By calculating the potential of the mean force as the particle moves from fluid A to the interface, the adsorption energy Ea can be obtained. When two homopolymer chains with types A and B are grafted to the opposite poles of the particle, Ea shows a scaling behavior with respect to chain length N: Ea ∝ N0.598. This is determined by the interactions between polymers and fluids. The enthalpy dominates, and the entropy effects mainly come from the rotational entropy loss of the polymer-grafted nanoparticle at interfaces, which disfavors the stabilization of particles at interfaces. When the grafted polymer number m is large, the adsorption energy exhibits a linear dependence on m. While the enthalpy dominates the behavior, the entropy becomes significant at a larger chain length of N = 15, where the configurational entropy of the polymer chains dominates the entropy of the system. The globule-coil transition occurs when polymers move from poor solvents to good solvents, increasing the configurational entropy and favoring the stabilization of particles at interfaces. Our study provides novel insights into the stabilization mechanism of polymer-grafted nanoparticles at interfaces and reveals the stabilization mechanism favored by the configurational entropy of grafted polymer chains.

Design and Evaluation of Inorganic/Organic Hybrid Bio-composite for Site-Specific Oral Delivery of Darifenacin

Benign hyperplasia (BHP) is a common disorder that affects men over the age of 60 years. Transurethral resection of the prostate (TURP) is the gold standard for operative treatment, but a range of drugs are also available to improve quality of life and to reduce BHP-associated urinary tract infections and complications. Darifenacin, an anti-muscarinic agent, has been found effective for relieving symptoms of overactive bladder associated with BHP, but the drug has poor solubility and bioavailability, which are major challenges in product development. An inorganic/organic bio-composite with gastric pH-resistant property was synthesized for the targeted oral delivery of Darifenacin to the lower gastrointestinal tract (GIT). This development was accomplished through co-precipitation of calcium carbonate in quince seed-based mucilage. The FTIR, XRD, DSC, and TGA results showed good drug-polymer compatibility, and the SEM images showed calcite formation in the quince hydrogel system. After 72 h, the drug release of 34% and 75% were observed in acidic (0.1N HCl) and 6.8 pH phosphate buffer, respectively. A restricted/less drug was permeated through gastric membrane (21.8%) as compared to permeation through intestinal membrane (65%.) The developed composite showed significant reduction in testosterone-induced prostatic hyperplasia (2.39 ± 0.12***) as compared to untreated diseased animal group. No sign of organ toxicity was observed against all the developed composites. In this study, we developed an inorganic-organic composite system that is highly biocompatible and effective for targeting the lower GIT, thereby avoiding the first-pass metabolism of darifenacin.

Recent advances in biomimetic cell membrane-camouflaged nanoparticles for cancer therapy

The emerging strategy of biomimetic nanoparticles (NPs) via cellular membrane camouflage holds great promise in cancer therapy. This scholarly review explores the utilization of cellular membranes derived from diverse cellular entities; blood cells, immune cells, cancer cells, stem cells, and bacterial cells as examples of NP coatings. The camouflaging strategy endows NPs with nuanced tumor-targeting abilities such as self-recognition, homotypic targeting, and long-lasting circulation, thus also improving tumor therapy efficacy overall. The comprehensive examination encompasses a variety of cell membrane camouflaged NPs (CMCNPs), elucidating their underlying targeted therapy mechanisms and delineating diverse strategies for anti-cancer applications. Furthermore, the review systematically presents the synthesis of source materials and methodologies employed in order to construct and characterize these CMCNPs, with a specific emphasis on their use in cancer treatment.

Engineered nanoparticles in non-invasive insulin delivery for precision therapeutics of diabetes

Diabetes mellitus is a chronic disease leading to the death of millions a year across the world. Insulin is required for Type 1, Type 2, and gestational diabetic patients, however, there are various modes of insulin delivery out of which oral delivery is noninvasive and convenient. Moreover, factors like insulin degradation and poor intestinal absorption play a crucial role in its bioavailability and effectiveness. This review discusses various types of engineered nanoparticles used in-vitro, in-vivo, and ex-vivo insulin delivery along with their administration routes and physicochemical properties. Injectable insulin formulations, currently in use have certain limitations, leading to invasiveness, low patient compliance, causing inflammation, and side effects. Based on these drawbacks, this review emphasizes more on the non-invasive route, particularly oral delivery. The article is important because it focuses on how engineered nanoparticles can overcome the limitations of free therapeutics (drugs alone), navigate the barriers, and accomplish precision therapeutics in diabetes. In future, more drugs could be delivered with a similar strategy to cure various diseases and resolve challenges in drug delivery. This review significantly describes the role of various engineered nanoparticles in improving the bioavailability of insulin by protecting it from various barriers during non-invasive routes of delivery.

Designing Dual-Responsive Drug Delivery Systems: The Role of Phase Change Materials and Metal-Organic Frameworks

Stimuli-responsive drug delivery systems (DDSs) offer precise control over drug release, enhancing therapeutic efficacy and minimizing side effects. This review focuses on DDSs that leverage the unique capabilities of phase change materials (PCMs) and metal-organic frameworks (MOFs) to achieve controlled drug release in response to pH and temperature changes. Specifically, this review highlights the use of a combination of lauric and stearic acids as PCMs that melt slightly above body temperature, providing a thermally responsive mechanism for drug release. Additionally, this review delves into the properties of zeolitic imidazolate framework-8 (ZIF-8), a stable MOF under physiological conditions that decomposes in acidic environments, thus offering pH-sensitive drug release capabilities. The integration of these materials enables the fabrication of complex structures that encapsulate drugs within ZIF-8 or are enveloped by PCM layers, ensuring that drug release is tightly controlled by either temperature or pH levels, or both. This review provides comprehensive insights into the core design principles, material selections, and potential biomedical applications of dual-stimuli responsive DDSs, highlighting the future directions and challenges in this innovative field.

An Evolutionary Review of Hemoperfusion Adsorbents: Materials, Preparation, Functionalization, and Outlook

Accumulation of pathogenic factors in the blood may cause irreversible damage and may even be life-threatening. Hemoperfusion is an effective technique for eliminating pathogenic factors, which is widely used in the treatment of various diseases including liver failure, renal failure, sepsis, and others. Hemoperfusion adsorbents are crucial in this process as they specifically bind and remove the target pathogenic factors. This review describes the development of hemoperfusion adsorbents, detailing the different properties exhibited by inorganic materials, organic polymers, and new materials. Advances in natural and synthetic polymers and novel materials manufacturing techniques have driven the expansion of hemoperfusion adsorbents in clinical applications. Stimuli-responsive (smart responsive) adsorbents with controllable molecular binding properties have many promising and environmentally friendly biomedical applications. Knowledge gaps, future research directions, and prospects for hemoperfusion adsorbents are discussed.

Nanomaterial-Driven Precision Immunomodulation: A New Paradigm in Therapeutic Interventions

Immunotherapy is a rapidly advancing field of research in the treatment of conditions such as cancer and autoimmunity. Nanomaterials can be designed for immune system manipulation, with precise targeted delivery and improved immunomodulatory efficacy. Here, we elaborate on various strategies using nanomaterials, including liposomes, polymers, and inorganic NPs, and discuss their detailed design intricacies, mechanisms, and applications, including the current regulatory issues. This type of nanomaterial design for targeting specific immune cells or tissues and controlling release kinetics could push current technological frontiers and provide new and innovative solutions for immune-related disorders and diseases without off-target effects. These materials enable targeted interactions with immune cells, thereby enhancing the effectiveness of checkpoint inhibitors, cancer vaccines, and adoptive cell therapies. Moreover, they allow for fine-tuning of immune responses while minimizing side effects. At the intersection of nanotechnology and immunology, nanomaterial-based platforms have immense potential to revolutionize patient-centered immunotherapy and reshape disease management. By prioritizing safety, customization, and compliance with regulatory standards, these systems can make significant contributions to precision medicine, thereby significantly impacting the healthcare landscape.

Innovative tumor interstitial fluid-triggered carbon dot-docetaxel nanoassemblies for targeted drug delivery and imaging of HER2-positive breast cancer

In this study, we have developed an innovative pH-triggered nanomedicine delivery system, targeting HER2-positive breast cancer cells for effective low-cost, imaging-guided drug delivery and precise therapy. The key feature of this system lies in its unique tumor interstitial fluid microenvironment-responsive drug release behavior which achieved tumor site-specific drug delivery. Our in vitro experiments demonstrated that the carbon dot-integrated material achieves more efficient DTX release (96.13 % at 72 h) in the tumor interstitial fluid microenvironment (pH 6.5), thereby boosting drug concentration at the tumor site and enhancing therapeutic efficacy. Further cell experiments confirmed the system's significant inhibitory effect on HER2-positive tumor cells SKBR3 in a pH 6.5 environment, and apoptosis assays indicating a notable increase in early cell apoptosis (from 8.39 % to 24.61 % compared with pH 7.4). Furthermore, the integration of HER2 aptamer within the carbon dot-based system enables targeted recognition and binding to tumor cells, ensuring more precise delivery of DTX while minimizing potential side effects. Crucially, the carbon dots in this system emit superior red fluorescence (the QY = 47.64 % excited at 535 nm compared with Rodamine 6G), enabling real-time visualization of the drug delivery process. This feature provides valuable feedback on treatment effectiveness, facilitating necessary adjustments. The small size (1.88 ± 0.48 nm) of carbon dots significantly improved their ability to penetrate biological barriers, while their low toxicity (no significant cell toxicity under 350 μg/mL) contributed to the formulation's outstanding biocompatibility. Overall, this carbon dot-enhanced drug delivery system offers immense potential for enhancing drug efficacy, minimizing side effects, and providing real-time treatment monitoring, thus proposing a innovate strategy for breast cancer therapy.

Guidelines derived from biomineralized tissues for design and construction of high-performance biomimetic materials: from weak to strong

Living organisms in nature have undergone continuous evolution over billions of years, resulting in the formation of high-performance fracture-resistant biomineralized tissues such as bones and teeth to fulfill mechanical and biological functions, despite the fact that most inorganic biominerals that constitute biomineralized tissues are weak and brittle. During the long-period evolution process, nature has evolved a number of highly effective and smart strategies to design chemical compositions and structures of biomineralized tissues to enable superior properties and to adapt to surrounding environments. Most biomineralized tissues have hierarchically ordered structures consisting of very small building blocks on the nanometer scale (nanoparticles, nanofibers or nanoflakes) to reduce the inherent weaknesses and brittleness of corresponding inorganic biominerals, to prevent crack initiation and propagation, and to allow high defect tolerance. The bioinspired principles derived from biomineralized tissues are indispensable for designing and constructing high-performance biomimetic materials. In recent years, a large number of high-performance biomimetic materials have been prepared based on these bioinspired principles with a large volume of literature covering this topic. Therefore, a timely and comprehensive review on this hot topic is highly important and contributes to the future development of this rapidly evolving research field. This review article aims to be comprehensive, authoritative, and critical with wide general interest to the science community, summarizing recent advances in revealing the formation processes, composition, and structures of biomineralized tissues, providing in-depth insights into guidelines derived from biomineralized tissues for the design and construction of high-performance biomimetic materials, and discussing recent progress, current research trends, key problems, future main research directions and challenges, and future perspectives in this exciting and rapidly evolving research field.

Cystine-cored diphenylalanine appended peptide-based self-assembled fluorescent nanostructures direct redox-responsive drug delivery

Fabrication of stimuli-responsive superstructure capable of delivering chemotherapeutics directly to the cancer cell by sparing healthy cells is crucial. Herein, we developed redox-responsive hollow spherical assemblies through self-assembly of disulfide-linked cysteine-diphenylalanine (SN). These fluorescent hollow spheres display intrinsic green fluorescence, are proteolytically stable and biocompatible, and allow for real-time monitoring of their intracellular entry. The disulfide bond facilitates selective degradation in the presence of high glutathione (GSH) concentrations, prevalent in cancer cells. We achieved efficient encapsulation (68.72%) of the anticancer drug doxorubicin (Dox) and demonstrated GSH-dependent, redox-responsive drug release within cancerous cells. SN-Dox exhibited a 20-fold lower effective concentration (2.5 μM) for compromising breast cancer cell viability compared to non-malignant cells (50 μM). The ability of SN-Dox to initiate DNA damage signaling and trigger apoptosis was comparable to that of the unencapsulated drug. Our findings highlight the potential of SN for creating site-specific drug delivery vehicles for sustained therapeutic release.

Zeolitic imidazolate framework-8: a versatile nanoplatform for tissue regeneration

Extensive research on zeolitic imidazolate framework (ZIF-8) and its derivatives has highlighted their unique properties in nanomedicine. ZIF-8 exhibits advantages such as pH-responsive dissolution, easy surface functionalization, and efficient drug loading, making it an ideal nanosystem for intelligent drug delivery and phototherapy. These characteristics have sparked significant interest in its potential applications in tissue regeneration, particularly in bone, skin, and nerve regeneration. This review provides a comprehensive assessment of ZIF-8's feasibility in tissue engineering, encompassing material synthesis, performance testing, and the development of multifunctional nanosystems. Furthermore, the latest advancements in the field, as well as potential limitations and future prospects, are discussed. Overall, this review emphasizes the latest developments in ZIF-8 in tissue engineering and highlights the potential of its multifunctional nanoplatforms for effective complex tissue repair.

Synthesis of an aggregation-induced emission (AIE) dye with pH-sensitivity based on tetraphenylethylene-pyridine for fluorescent nanoparticles and its applications in bioimaging and in vitro anti-tumor effect

In this contribution, a novel AIE monomers 2-(4-styrylphenyl)- 1,2-diphenylvinyl)styryl)pyridine (SDVPY) with smart fluorescent pH-sensitivity basing on tetraphenylethylene-pyridine were successfully synthesized for the first time, subsequently, a series of amphiphilic copolymers PEG-PY were achieved by reversible addition-fragmentation chain transfer (RAFT) polymerization of SDVPY and poly(ethylene glycol) methacrylate (PEGMA), which would self-assemble in water solution to form core-shell nanoparticles (PEG-PY FONs) with about 150 nm diameter. The PEG-PY FONs showed obvious fluorescence response to Fe3+, HCO3- and CO32- ions in aqueous solution owing to their smart pH-sensitivity and AIE characteristics, and their maximum emission wavelength could reversibly change from 525 nm to 624 nm. The as-prepared PEG-PY FONs showed also prospective application in cells imaging with the variable fluorescence for different pH cells micro-environment. When PEG-PY copolymers self-assembled with the anti-tumor drug paclitaxel (PTX), the obtained PY-PTX FONs could effectively deliver and release PTX with pH-sensitivity, and could be easily internalized by A549 cells and located at the cytoplasm with high cytotoxicity, which was further confirmed by the Calcein-AM/PI staining of dead and alive A549 cells. Moreover, the flow cytometry results indicated that the PY-PTX FONs could obviously induce the apoptosis of A549 cells, which further showed the great potential of PY-PTX FONs in the application of tumors therapy.

Exploring the potential of pH-sensitive polymers in targeted drug delivery

The pH-sensitive polymers have attained significant attention in the arena of targeted drug delivery (TDD) because of their exceptional capability to respond to alteration in pH in various physiological environments. This attribute aids pH-sensitive polymers to act as smart carriers for therapeutic agents, transporting them precisely to target locations while curtailing the release of drugs in off-targeted sites, thereby diminishing side effects. Many pH-responsive polymers in TDD have revealed promising results, with increased therapeutic efficacy and decreased toxic effects. Several pH-sensitive polymers, including, hydroxy-propyl-methyl cellulose, poly (methacrylic acid) (Eudragit series), poly (acrylic acid), and chitosan, have been broadly studied for their myriad applications in the management of various types of diseases. Additionally, the amalgamation of pH-sensitive polymers with, additive manufacturing techniques like 3D printing, has resulted in the progression of novel drug delivery systems that regulate drug release in a controlled manner. Herein, types of pH-sensitive polymers in TDD are systemically reviewed. We have briefly discussed the nanocarriers employed for the delivery of various pH-sensitive polymers in TDD. Finally, miscellaneous applications of pH-sensitive polymers are discussed thoroughly with special attention to the implication of 3D printing in pH-sensitive polymers.

Miniaturized fluorescence pH sensor with assembly free ball lens on a tapered multimode optical fiber

In biochemistry, the absence of a compact, assembly-free pH sensor with high sensitivity and signal-to-noise ratio has been a persistent hurdle in achieving accurate pH measurements in real time, particularly in complex liquid environments. This manuscript introduces what we believe to be a novel solution in the form of a miniaturized pH sensor utilizing an assembly-free ball lens on a tapered multimode optical fiber (TMMF), offering the potential to revolutionize pH sensing in biochemical applications. A multimode optical fiber (MMF) was subjected to tapering processes, leading to the creation of an ultra-thin needle-like structure with a cross-sectional diameter of about 12.5 µm and a taper length of 3 mm. Subsequently, a ball lens possessing a diameter of 20 µm was fabricated at the apex of the taper. The resultant structure was coated utilizing the dip-coating technique, involving a composite mixture of epoxy and pH-sensitive dye, 2',7'-bis(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF), thereby ensconcing the tapered ball lens with dye molecules for pH sensing. This study encompassed the fabrication and evaluation of six distinct fiber structures, incorporating the cleaved endface, the convex lens, and the ball lens structures to compare light focal lengths and propagation intensities. Computational simulations and numerical analyses were conducted to elucidate the encompassing light focal distances across the full array of lens configurations. The efficacy of the proposed pH sensor was subsequently assessed through its deployment within a complex liquid medium spanning a pH spectrum ranging from 6 to 8. Real-time data acquisition was performed with a fast response time of 0.5 seconds. A comparative analysis with a pH sensor predicated upon a single TMMF embedded with the fluorescent dye underscored the substantial signal enhancement achieved by the proposed system twice the fluorescence signal magnitude. The proposed assembly-free miniaturized pH sensor not only substantiates enhanced signal collection efficiency but also decisively addresses the persistent challenges of poor signal-to-noise ratio encountered within contemporary miniaturized pH probes.

Drug Polymeric Carrier of Aceclofenac Based on Amphiphilic Chitosan Micelles

Amphiphilic micelles based on chitosan (CS) were applied as drug carriers of aceclofenac (ACF) as a potential method to induce its bioavailability and therapeutic efficiency. N-octyl-N,O-succinyl CS (OSCS), an amphiphilic CS derivative, was successfully synthesized and loaded physically by ACF at different pH values and using different dosages of ACF, forming ACF-loaded polymeric micelles (PMs). The obtained PMs and ACF-loaded PMs were characterized by different analytical techniques, including AFM, TEM, DLS, UV-vis spectrophotometry, 1H NMR spectroscopy, and FT-IR spectroscopy. The pH 5 sample with a 30% ACF/polymer ratio showed the highest ACF loading capacity (LC) and entrapment efficiency (EE). In vitro release behaviors of pure ACF and ACF-loaded PMs at each release point indicated that the release profile of pH-responsive PMs loaded with ACF demonstrated quicker release rates (94% after 480 min) compared to the release behavior noticed for free ACF (59.56% after 480 min). Furthermore, the release rates exhibit a notable rise when the pH is increased from 1.2 to 4.7. In the carrageenan-induced inflammation model of paw edema in rats, it has been demonstrated that the injection of ACF-loaded PMs (at a dose of 10 mg/kg) resulted in a strengthened inflammatory activity compared to the injection of free ACF at equivalent dosages as well as at time intervals. However, the use of ACF-loaded PMs for a duration of 6 h displayed a notable reduction of paw edema, with an inhibition percentage of 85.09%, in contrast to the 74.9% inhibition percentage observed for the free ACF medication.

Material and Design Toolkit for Drug Delivery: State of the Art, Trends, and Challenges

The nanomaterial and related toolkit have promising applications for improving human health and well-being. Nanobased drug delivery systems use nanoscale materials as carriers to deliver therapeutic agents in a targeted and controlled manner, and they have shown potential to address issues associated with conventional drug delivery systems. They offer benefits for treating various illnesses by encapsulating or conjugating biological agents, chemotherapeutic drugs, and immunotherapeutic agents. The potential applications of this technology are vast; however, significant challenges exist to overcome such as safety issues, toxicity, efficacy, and insufficient capacity. This article discusses the latest developments in drug delivery systems, including drug release mechanisms, material toolkits, related design molecules, and parameters. The concluding section examines the limitations and provides insights into future possibilities.

Emerging drug delivery systems with traditional routes - A roadmap to chronic inflammatory diseases

Inflammation is prevalent and inevitable in daily life but can generally be accommodated by the immune systems. However, incapable self-healing and persistent inflammation can progress to chronic inflammation, leading to prevalent or fatal chronic diseases. This review comprehensively covers the topic of emerging drug delivery systems (DDSs) for the treatment of chronic inflammatory diseases (CIDs). First, we introduce the basic biology of the chronic inflammatory process and provide an overview of the main CIDs of the major organs. Next, up-to-date information on various DDSs and the associated strategies for ensuring targeted delivery and stimuli-responsiveness applied to CIDs are discussed extensively. The implementation of traditional routes of drug administration to maximize their therapeutic effects against CIDs is then summarized. Finally, perspectives on future DDSs against CIDs are presented.

Novel Vectors and Administrations for mRNA Delivery

mRNA therapy has shown great potential in infectious disease vaccines, cancer immunotherapy, protein replacement therapy, gene editing, and other fields due to its central role in all life processes. However, mRNA is challenging to pass through the cell membrane due to its significant negative charges and degradation from RNase, so the key to mRNA therapy is efficient packaging and delivery of it with appropriate vectors. Presently researchers have developed various vectors such as viruses and liposomes, but these conventional vectors are now difficult to meet the growing requirement like safety, efficiency, and targeting, so many novel delivery vectors with unique advantages have emerged recently. This review mainly introduces two categories of novel vectors: biomacromolecules and inorganic nanoparticles, as well as two novel methods of control and administration based on these novel vectors: controlled-release administration and non-invasive administration. These novel delivery strategies have the advantages of high safety, biocompatibility, versatility, intelligence, and targeting. This paper analyzes the challenges faced by the field of mRNA delivery in depth, and discusses how to use the characteristics of novel vectors and administrations to solve these problems.

Role of Nanoparticle-Conjugates and Nanotheranostics in Abrogating Oxidative Stress and Ameliorating Neuroinflammation

Oxidative stress is a deteriorating condition that arises due to an imbalance between the reactive oxygen species and the antioxidant system or defense of the body. The key reasons for the development of such conditions are malfunctioning of various cell organelles, such as mitochondria, endoplasmic reticulum, and Golgi complex, as well as physical and mental disturbances. The nervous system has a relatively high utilization of oxygen, thus making it particularly vulnerable to oxidative stress, which eventually leads to neuronal atrophy and death. This advances the development of neuroinflammation and neurodegeneration-associated disorders such as Alzheimer's disease, Parkinson's disease, epilepsy, dementia, and other memory disorders. It is imperative to treat such conditions as early as possible before they worsen and progress to irreversible damage. Oxidative damage can be negated by two mechanisms: improving the cellular defense system or providing exogenous antioxidants. Natural antioxidants can normally handle such oxidative stress, but they have limited efficacy. The valuable features of nanoparticles and/or nanomaterials, in combination with antioxidant features, offer innovative nanotheranostic tools as potential therapeutic modalities. Hence, this review aims to represent novel therapeutic approaches like utilizing nanoparticles with antioxidant properties and nanotheranostics as delivery systems for potential therapeutic applications in various neuroinflammation- and neurodegeneration-associated disease conditions.

Investigations into the effects of scaffold microstructure on slow-release system with bioactive factors for bone repair

In recent years, bone tissue engineering (BTE) has played an essential role in the repair of bone tissue defects. Although bioactive factors as one component of BTE have great potential to effectively promote cell differentiation and bone regeneration, they are usually not used alone due to their short effective half-lives, high concentrations, etc. The release rate of bioactive factors could be controlled by loading them into scaffolds, and the scaffold microstructure has been shown to significantly influence release rates of bioactive factors. Therefore, this review attempted to investigate how the scaffold microstructure affected the release rate of bioactive factors, in which the variables included pore size, pore shape and porosity. The loading nature and the releasing mechanism of bioactive factors were also summarized. The main conclusions were achieved as follows: i) The pore shapes in the scaffold may have had no apparent effect on the release of bioactive factors but significantly affected mechanical properties of the scaffolds; ii) The pore size of about 400 μm in the scaffold may be more conducive to controlling the release of bioactive factors to promote bone formation; iii) The porosity of scaffolds may be positively correlated with the release rate, and the porosity of 70%-80% may be better to control the release rate. This review indicates that a slow-release system with proper scaffold microstructure control could be a tremendous inspiration for developing new treatment strategies for bone disease. It is anticipated to eventually be developed into clinical applications to tackle treatment-related issues effectively.

Site-selective post-modification of short α/γ hybrid foldamers: a powerful approach for molecular diversification towards biomedical applications

The extensive research work in the exhilarating area of foldamers (artificial oligomers possessing well-defined conformation in solution) has shown them to be promising candidates in biomedical research and materials science. The post-modification approach is successful in peptides, proteins, and polymers to modulate their functions. To the best of our knowledge, site-selective post-modification of a foldamer affording molecules with different pendant functional groups within a molecular scaffold has not yet been reported. We demonstrate for the first time that late-stage site-selective functionalization of short hybrid oligomers is an efficient approach to afford molecules with diverse functional groups. In this article, we report the design and synthesis of hybrid peptides with repeating units of leucine (Leu) and 5-amino salicylic acid (ASA), regioselective post-modification, conformational analyses (based on solution-state NMR, circular dichroism and computational studies) and morphological studies of the peptide nanostructures. As a proof-of-concept, we demonstrate the applications of differently modified peptides as drug delivery agents, imaging probes, and anticancer agents. The novel feature of the work is that the difference in reactivity of two phenolic OH groups in short biomimetic peptides was utilized to achieve site-selective post-modification. It is challenging to apply the same approach to short α-peptides having a poor folding tendency, and their post-functionalization may considerably affect their conformation.

Multifunctional hydrogels: advanced therapeutic tools for osteochondral regeneration

Various joint pathologies such as osteochondritis dissecans, osteonecrosis, rheumatic disease, and trauma, may result in severe damage of articular cartilage and other joint structures, ranging from focal defects to osteoarthritis (OA). The osteochondral unit is one of the critical actors in this pathophysiological process. New approaches and applications in tissue engineering and regenerative medicine continue to drive the development of OA treatment. Hydrogel scaffolds, a component of tissue engineering, play an indispensable role in osteochondral regeneration. In this review, tissue engineering strategies regarding osteochondral regeneration were highlighted and summarized. The application of hydrogels for osteochondral regeneration within the last five years was evaluated with an emphasis on functionalized physical and chemical properties of hydrogel scaffolds, functionalized delivery hydrogel scaffolds as well as functionalized intelligent response hydrogel scaffolds. Lastly, to serve as guidance for future efforts in the creation of bioinspired hydrogel scaffolds, a succinct summary and new views for specific mechanisms, applications, and existing limitations of the newly designed functionalized hydrogel scaffolds were offered.

Cargo-Dependent Targeted Cellular Uptake Using Quaternized Starch as a Carrier

The tailored design of drug delivery systems for specific therapeutic agents is a prevailing approach in the field. In this paper, we present a study that highlights the potential of our modified starch, Q-starch, as a universal and adaptable drug delivery carrier for diverse therapeutic agents. We investigate the ability of Q-starch/cargo complexes to target different organelles within the cellular landscape, based on the specific activation sites of therapeutic agents. Plasmid DNA (pDNA), small interfering RNA (siRNA), and phosphatidylinositol (3,4,5)-trisphosphate (PIP3) were chosen as representative therapeutic molecules, acting in the nucleus, cytoplasm, and membrane, respectively. By carrying out comprehensive characterizations, employing dynamic light scattering (DLS), determining the zeta potential, and using cryo-transmitting electron microscopy (cryo-TEM), we reveal the formation of nano-sized, positively charged, and spherical Q-starch complexes. Our results demonstrate that these complexes exhibit efficient cellular uptake, targeting their intended organelles while preserving their physical integrity and functionality. Notably, the intracellular path of the Q-starch/cargo complex is guided by the cargo itself, aligning with its unique biological activity site. This study elucidates the versatility and potency of Q-starch as a versatile drug delivery carrier, paving the way for novel applications offering targeted delivery strategies for potential therapeutic molecules.

pH-Responsive Biomaterials for the Treatment of Dental Caries-A Focussed and Critical Review

Dental caries is a common and costly multifactorial biofilm disease caused by cariogenic bacteria that ferment carbohydrates to lactic acid, demineralizing the inorganic component of teeth. Therefore, low pH (pH 4.5) is a characteristic signal of the localised carious environment, compared to a healthy oral pH range (6.8 to 7.4). The development of pH-responsive delivery systems that release antibacterial agents in response to low pH has gained attention as a targeted therapy for dental caries. Release is triggered by high levels of acidogenic species and their reduction may select for the establishment of health-associated biofilm communities. Moreover, drug efficacy can be amplified by the modification of the delivery system to target adhesion to the plaque biofilm to extend the retention time of antimicrobial agents in the oral cavity. In this review, recent developments of different pH-responsive nanocarriers and their biofilm targeting mechanisms are discussed. This review critically discusses the current state of the art and innovations in the development and use of smart delivery materials for dental caries treatment. The authors' views for the future of the field are also presented.

Current Principles, Challenges, and New Metrics in pH-Responsive Drug Delivery Systems for Systemic Cancer Therapy

The paradigm of drug delivery via particulate formulations is one of the leading ideas that enable overcoming limitations of traditional chemotherapeutic agents. The trend toward more complex multifunctional drug carriers is well-traced in the literature. Nowadays, the prospectiveness of stimuli-responsive systems capable of controlled cargo release in the lesion nidus is widely accepted. Both endogenous and exogenous stimuli are employed for this purpose; however, endogenous pH is the most common trigger. Unfortunately, scientists encounter multiple challenges on the way to the implementation of this idea related to the vehicles' accumulation in off-target tissues, their immunogenicity, the complexity of drug delivery to intracellular targets, and finally, the difficulties in the fabrication of carriers matching all imposed requirements. Here, we discuss fundamental strategies for pH-responsive drug delivery, as well as limitations related to such carriers' application, and reveal the main problems, weaknesses, and reasons for poor clinical results. Moreover, we attempted to formulate the profiles of an "ideal" drug carrier in the frame of different strategies drawing on the example of metal-comprising materials and considered recently published studies through the lens of these profiles. We believe that this approach will facilitate the formulation of the main challenges facing researchers and the identification of the most promising trends in technology development.

Theranostics Nanomedicine Applications for Colorectal Cancer and Metastasis: Recent Advances

Colorectal cancer (CRC) is the third most common cancer worldwide, and metastatic CRC is a fatal disease. The CRC-affected tissues show several molecular markers that could be used as a fresh strategy to create newer methods of treating the condition. The liver and the peritoneum are where metastasis occurs most frequently. Once the tumor has metastasized to the liver, peritoneal carcinomatosis is frequently regarded as the disease's final stage. However, nearly 50% of CRC patients with peritoneal carcinomatosis do not have liver metastases. New diagnostic and therapeutic approaches must be developed due to the disease's poor response to present treatment choices in advanced stages and the necessity of an accurate diagnosis in the early stages. Many unique and amazing nanomaterials with promise for both diagnosis and treatment may be found in nanotechnology. Numerous nanomaterials and nanoformulations, including carbon nanotubes, dendrimers, liposomes, silica nanoparticles, gold nanoparticles, metal-organic frameworks, core-shell polymeric nano-formulations, and nano-emulsion systems, among others, can be used for targeted anticancer drug delivery and diagnostic purposes in CRC. Theranostic approaches combined with nanomedicine have been proposed as a revolutionary approach to improve CRC detection and treatment. This review highlights recent studies, potential, and challenges for the development of nanoplatforms for the detection and treatment of CRC.

Anti-inflammatory and anti-biotic drug metronidazole loaded ZIF-90 nanoparticles as a pH responsive drug delivery system for improved pediatric sepsis management

Sepsis is a life-threatening disease caused by the dis-functioning of the immune response to pathogenic infections. Despite, the discovery of modern therapeutics and treatments of sepsis are lacking due to the resistance of pathogens. Metronidazole is an antibiotic commonly used to treat bacterial infections, but usage is limited and challenging by a short half-life period. In this research work, fabricate a pH-responsive drug delivery system for controlled release of metronidazole targeted molecules. We exemplified that, the encapsulation of hydrophilic metronidazole drug within a hydrophobic ZIF-90 framework can be enhanced the pH-responsive drug release under acidic conditions. The ZIF-90 frameworks only decompose in under acidic solutions, they are highly stable in physiological conditions. The pH-responsive protonation mechanism of ZIF-90 frameworks promotes the quick release of metronidazole within cells. The antimicrobial proficiency of zinc and metronidazole will expose a synergistic effect in ROS-mediated bacterial inhibition and auto-immunity boosting of normal cells. In vitro, antibacterial activity results revealed that the MI@ZIF-90 nano drug delivery system effectively eradicated human infectious pathogens at the lowest concentrations. In anti-fungal activity, studies show excellent growth inhibition against human pathogenic fungi Aspergillus fumigatus and Candida albicans. Finally, the PBMC cytocompatibility study concludes, that the fabricated MI@ZIF-90 drug delivery system is non-toxic to biomedical applications. The overall research findings highlight the design of a smart drug delivery system for sepsis treatment. In future it will be an efficient, low-cost, and biocompatible pharmaceutics for pediatric sepsis management processes.

Graphene-based nanomaterials for stimuli-sensitive controlled delivery of therapeutic molecules

Stimuli-responsive drug delivery has attracted tremendous attention in the past decades. It provides a spatial- and temporal-controlled release in response to different triggers, thus enabling highly efficient drug delivery and minimizing drug side effects. Graphene-based nanomaterials have been broadly explored, and they show great potential in smart drug delivery due to their stimuli-responsive behavior and high loading capacity for an extended range of drug molecules. These characteristics are a result of high surface area, mechanical stability and chemical stability, and excellent optical, electrical, and thermal properties. Their great and infinite functionalization potential also allows them to be integrated into several types of polymers, macromolecules, or other nanoparticles, leading to the fabrication of novel nanocarriers with enhanced biocompatibility and trigger-sensitive properties. Thus, numerous studies have been dedicated to graphene modification and functionalization. In the current review, we introduce graphene derivatives and different graphene-based nanomaterials utilized in drug delivery and discuss the most important advances in their functionalization and modification. Also, their potential and progress in an intelligent drug release in response to different types of stimuli either endogenous (pH, redox conditions, and reactive oxygen species (ROS)) or exogenous (temperature, near-infrared (NIR) radiation, and electric field) will be debated.

Multi-responsive on-demand drug delivery PMMA-co-PDEAEMA platform based on CO2, electric potential, and pH switchable nanofibrous membranes

This study investigated the release characteristics of curcumin (CUR)-loaded switchable poly(methyl methacrylate)-co-poly(N,N-diethylaminoethyl methacrylate) (PMMA-co-PDEAEMA) membranes following the application of various stimuli, as well as the platform's applicability in wound dressing and tissue engineering applications. The free-radical polymerization method was used to synthesize the PMMA-co-PDEAEMA copolymer. The drug-loaded nanofibrous membrane with electric potential (EP)-, CO₂-, and pH-responsive properties was developed by the electrospinning of PMMA-co-PDEAEMA and CUR. The resulted structure was characterized by a scanning electron microscope (SEM) coupled with X-ray energy dispersive spectroscopy and wide-angle X-ray scattering measurements. The release characteristics of the CUR-loaded wound covering were analyzed in various simulated environments at varying voltages, alternated CO₂/N₂ gas bubbling, and at two different pH values; the results demonstrated high drug release controllability. Loaded CUR displayed high stability and better solubility compared with free CUR. The CUR-loaded tissue also exhibited high antibacterial activity against Escherichia coli and staphylococcus aureus bacteria. In addition, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay depicted high biocompatibility of up to 95% in the CUR-loaded membrane. This platform could be a promising candidate for usage in tissue engineering and medical applications such as targeted drug delivery, biodetection, reversible cell capture-and-release systems, and biosensors.

pH-responsive and targeted delivery of chrysin via folic acid-functionalized mesoporous silica nanocarrier for breast cancer therapy

Cancer is a disease of global importance. In order to mitigate conventional chemotherapy-related side effects, phytochemicals with inherent anticancer efficacy have been opted. However, the use of nanotechnology is essential to enhance the bioavailability and therapeutic efficacy of these phytochemicals. Herein, we have formulated folic acid conjugated polyacrylic acid capped mesoporous silica nanoparticles (∼47.6 nm in diameter) for pH-dependent targeted delivery of chrysin to breast cancer (MCF-7) cells. Chrysin loaded mesoporous silica nanoparticles (Chr- mSiO2@PAA/FA) have been noted to induce apoptosis in MCF-7 cells through oxidative insult and mitochondrial dysfunction with subsequent G1 arrest. Further, in tumor bearing mice, intravenous incorporation of Chr-mSiO2@PAA/FA has been noticed to enhance the anti-neoplastic effects of chrysin via tumor site-specific accumulation. Enhanced cytotoxicity of chrysin contributed towards in vivo tumor regression, restoration of normalized tissue architecture and maintenance of healthy body weight. Besides, no serious systemic toxicity was manifested in response to Chr-mSiO2@PAA/FA administration in vivo. Thus, the study evokes about the anticancer potentiality of chrysin and its increased therapeutic activity via incorporation into folic acid conjugated mesoporous silica nanoparticles, which may hold greater impact in field of future biomedical research.

Dendrimers as Modifiers of Inorganic Nanoparticles for Therapeutic Delivery in Cancer

The formulation of nanoscale systems with well-defined sizes and shapes is of great interest in applications such as drug and gene delivery, diagnostics and imaging. Dendrimers are polymers that have attracted interest due to their size, shape, branching length, amine density, and surface functionalities. These unique characteristics of dendrimers set them apart from other polymers, their ability to modify nanoparticles (NPs) for biomedical applications. Dendrimers are spherical with multiple layers over their central core, each representing a generation. Their amphiphilic nature and hollow structure allow for the incorporation of multiple drugs or genes, in addition to enabling easy surface modification with cellular receptor-targeting moieties to ensure site-specific delivery of therapeutics. Dendrimers are employed in chemotherapeutic applications for the delivery of anticancer drugs. There are many inorganic NPs currently being investigated for cancer therapy, each with their own unique biological, chemical, and physical properties. To favor biomedical applications, inorganic NPs require suitable polymers to ensure stability, biodegradability and target specificity. The success of dendrimers is dependent on their unique structure, good bioavailability and stability. In this review, we describe the properties of dendrimers and their use as modifiers of inorganic NPs for enhanced therapeutic delivery. Herein, we review the significant developments in this area from 2015 to 2022. Databases including Web of Science, Scopus, Google Scholar, Science Direct, BioMed Central (BMC), and PubMed were searched for articles using dendrimers, inorganic nanoparticles and cancer as keywords.

Laser-activated nanoparticles for ultrasound/photoacoustic imaging-guided prostate cancer treatment

Prostate cancer (PCa) is the most common malignant tumor in men. Prostate-specific membrane antigen (PSMA), which is overexpressed on the surface of Prostate cancer cells, may serve as a potential therapeutic target. Recently, image-guided and targeted therapy for prostate cancers has attracted much attention by using Prostate-specific membrane antigen targeting nanoparticle. In this study, we produced PSMA-targeted light-responsive nanosystems. These nanosystems of liquid perfluorocarbon cores and polymer shells were loaded with the photosensitizer IR780 and therapeutic drugs paclitaxel. The liquid perfluorocarbon (PFP) in nanoparticles can perform ultrasound-enhanced imaging by liquid-gas transition and promote the deliver and release of paclitaxel. IR780 can perform photothermal therapy (PTT) guided by photoacoustic (PA) imaging. Combination treatment with photothermal therapy and chemotherapy exhibited excellent inhibition of cell proliferation in vitro and a significant therapeutic effect in vivo. In conclusion, we successfully formulated PSMA-targeted nanosystems with precision targeting and ultrasound/PA dual-modality imaging for anti-tumor effects.

Functional Hydrogels and Their Applications in Craniomaxillofacial Bone Regeneration

Craniomaxillofacial bone defects are characterized by an irregular shape, bacterial and inflammatory environment, aesthetic requirements, and the need for the functional recovery of oral-maxillofacial areas. Conventional clinical treatments are currently unable to achieve high-quality craniomaxillofacial bone regeneration. Hydrogels are a class of multifunctional platforms made of polymers cross-linked with high water content, good biocompatibility, and adjustable physicochemical properties for the intelligent delivery of goods. These characteristics make hydrogel systems a bright prospect for clinical applications in craniomaxillofacial bone. In this review, we briefly demonstrate the properties of hydrogel systems that can come into effect in the field of bone regeneration. In addition, we summarize the hydrogel systems that have been developed for craniomaxillofacial bone regeneration in recent years. Finally, we also discuss the prospects in the field of craniomaxillofacial bone tissue engineering; these discussions can serve as an inspiration for future hydrogel design.

Research progress of stimulus-responsive antibacterial materials for bone infection

Infection is one of the most serious complications harmful to human health, which brings a huge burden to human health. Bone infection is one of the most common and serious complications of fracture and orthopaedic surgery. Antibacterial treatment is the premise of bone defect healing. Among all the antibacterial strategies, irritant antibacterial materials have unique advantages and the ability of targeted therapy. In this review, we focus on the research progress of irritating materials, the development of antibacterial materials and their advantages and disadvantages potential applications in bone infection.

Facile Fabrication of Methyl Gallate Encapsulated Folate ZIF-L Nanoframeworks as a pH Responsive Drug Delivery System for Anti-Biofilm and Anticancer Therapy

Zeolitic imidazole frameworks are emerging materials and have been considered an efficient platform for biomedical applications. The present study highlights the simple fabrication of methyl gallate encapsulated folate-ZIF-L nanoframeworks (MG@Folate ZIF-L) by a simple synthesis. The nanoframeworks were characterized by different sophisticated instruments. In addition, the drug-releasing mechanism was evidenced by in vitro releasing kinetics at various pH conditions. The anti-biofilm potential confirmed by the biofilm architectural deformations against human infectious pathogens MRSA and N7 clinical strains. Furthermore, anticancer efficacy assessed against A549 lung cancer cells. The result reveals that the MG@Folate ZIF-L exposed a superior cytotoxic effect due to the pH-responsive and receptor-based drug-releasing mechanism. Based on the unique physicochemical and biological characteristics of nanoframeworks, it has overcome the problems of undesired side effects and uncontrolled drug release of existing drug delivery systems. Finally, the in vitro toxicity effect of MG@Folate ZIF-L was tested against the Artemia salina (A. salina) model organism, and the results show enhanced biocompatibility. Overall, the study suggested that the novel MG@Folate ZIF-L nanoframeworks is a suitable material for biomedical applications. It will be very helpful to the future design for targeted drug delivery systems.

Recent Advances in Metal-Organic-Framework-Based Nanocarriers for Controllable Drug Delivery and Release

Metal-organic frameworks (MOFs) have a good designability, a well-defined pore, stimulus responsiveness, a high surface area, and a controllable morphology. Up to now, various MOFs have been widely used as nanocarriers and have attracted lots of attention in the field of drug delivery and release because of their good biocompatibility and high-drug-loading capacity. Herein, we provide a comprehensive summary of MOF-based nanocarriers for drug delivery and release over the last five years. Meanwhile, some representative examples are highlighted in detail according to four categories, including the University of Oslo MOFs, Fe-MOFs, cyclodextrin MOFs, and other MOFs. Moreover, the opportunities and challenges of MOF-based smart delivery vehicles are discussed. We hope that this review will be helpful for researchers to understand the recent developments and challenges of MOF-based drug-delivery systems.

Recent advances in responsive hydrogels for diabetic wound healing

Poor wound healing after diabetes mellitus remains a challenging problem, and its pathophysiological mechanisms have not yet been fully elucidated. Persistent bleeding, disturbed regulation of inflammation, blocked cell proliferation, susceptible infection and impaired tissue remodeling are the main features of diabetic wound healing. Conventional wound dressings, including gauze, films and bandages, have a limited function. They generally act as physical barriers and absorbers of exudates, which fail to meet the requirements of the whol diabetic wound healing process. Wounds in diabetic patients typically heal slowly and are susceptible to infection due to hyperglycemia within the wound bed. Once bacterial cells develop into biofilms, diabetic wounds will exhibit robust drug resistance. Recently, the application of stimuli-responsive hydrogels, also known as "smart hydrogels", for diabetic wound healing has attracted particular attention. The basic feature of this system is its capacities to change mechanical properties, swelling ability, hydrophilicity, permeability of biologically active molecules, etc., in response to various stimuli, including temperature, potential of hydrogen (pH), protease and other biological factors. Smart hydrogels can improve therapeutic efficacy and limit total toxicity according to the characteristics of diabetic wounds. In this review, we summarized the mechanism and application of stimuli-responsive hydrogels for diabetic wound healing. It is hoped that this work will provide some inspiration and suggestions for research in this field.

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.