Enzymatically controlled responsive drug delivery systems

Promising strategies for smart insulin delivery system: Glucose-sensitive microneedle

The diabetes treatment landscape is rapidly evolving towards intelligent and precise therapeutic interventions. Among these advancements, glucose-sensitive microneedle patches (GSMPs), which can automatically adjust the transdermal release rate of insulin based on glucose concentrations, are emerging as a promising strategy. In this work, a new classification method has been proposed for GSMPs, categorizing them into integrated, all-in-one, and core-shell structures. The working mechanism and performance of GSMPs are thoroughly analyzed to compare the advantages and disadvantages of these three forms. The correlation between glucose-sensitive performance and normal blood glucose maintenance time (NGT) is further explored. Our findings indicate that all-in-one GSMPs demonstrate a positive correlation between in vitro glucose-sensitive controlled-release performance and NGT, unlike assembled GSMPs, where the performance is influenced by the matrix material and crosslinking factors. Simultaneously, challenges in clinical translation and future development trends are discussed from a patient's perspective. In summary, the new classification method, in-depth explanation of mechanisms, and analysis of challenges in this work contribute to a better understanding of the field of GSMPs and provide guidance for the development of more advanced and efficient GSMPs.

Exploring enzyme-immobilized MOFs and their application potential: biosensing, biocatalysis, targeted drug delivery and cancer therapy

Enzymes are indispensable in several applications including biosensing and degradation of pollutants and in the drug industry. However, adverse conditions restrict enzymes' utility in biocatalysis due to their inherent limitations. Metal-organic frameworks (MOFs), with their robust structure, offer an innovative avenue for enzyme immobilization, enhancing their resilience against harsh solvents and temperatures. This advancement is pivotal for application in bio-sensing, bio-catalysis, and specifically, targeted drug delivery in cancer therapy, where enzyme-MOF composites enable precise therapeutic localization, minimizing the side effects of traditional treatment. The adaptable nature of MOFs enhances drug biocompatibility and availability, significantly improving therapeutic outcomes. Moreover, the integration of enzyme-immobilized MOFs into bio-sensing represents a leap forward in the rapid and accurate identification of biomarkers, facilitating early diagnosis and disease monitoring. In bio-catalysis, this synergy promotes efficient and environmentally safe chemical synthesis, enhancing reaction rates and yields and broadening the scope of enzyme application in pharmaceutical and bio-fuel production. This review article explores the immobilization techniques and their biomedical applications, specifically focusing on drug delivery in cancer therapy and bio-sensing. Additionally, it addresses the challenges faced in this expanding field.

Drug-Eluting Sutures by Hot-Melt Extrusion: Current Trends and Future Potentials

Surgical site infections (SSIs) may result from surgical procedures requiring a secondary administration of drugs at site or systemically in treating the infection. Drug-eluting sutures containing antimicrobial agents symbolise a latent strategy that precludes a secondary drug administration. It also offers the possibility of delivering a myriad of therapeutic agents to a localised wound site to effect analgesia, anti-inflammation, or the deployment of proteins useful for wound healing. Further, the use of biodegradable drug-eluting sutures eliminates the need for implanting foreign material into the wound, which needs to be removed after healing. In this review, we expound on recent trends in the manufacture of drug-eluting sutures with a focus on the hot-melt extrusion (HME) technique. HME provides a solvent-free, continuous one-step manufacturing conduit for drug-eluting sutures, hence, there is no drying step, which can be detrimental to the drug or suture threads and, thus, environmentally friendly. There is the possibility of combining the technology with additive manufacturing platforms to generate personalised drug-loaded implantable devices through prototyping and scalability. The review also highlights key material requirements for fabricating drug-eluting sutures by HME, as well as quality attributes. Finally, a preview of emerging drug-eluting sutures and advocacy for harmonisation of quality assurance by regulatory authorities that permits quality evaluation of novelty sutures is presented.

Harnessing Ultrasound for Targeting Drug Delivery to the Brain and Breaching the Blood–Brain Tumour Barrier

Despite significant advances in developing drugs to treat brain tumours, achieving therapeutic concentrations of the drug at the tumour site remains a major challenge due to the presence of the blood–brain barrier (BBB). Several strategies have evolved to enhance brain delivery of chemotherapeutic agents to treat tumours; however, most approaches have several limitations which hinder their clinical utility. Promising studies indicate that ultrasound can penetrate the skull to target specific brain regions and transiently open the BBB, safely and reversibly, with a high degree of spatial and temporal specificity. In this review, we initially describe the basics of therapeutic ultrasound, then detail ultrasound-based drug delivery strategies to the brain and the mechanisms by which ultrasound can improve brain tumour therapy. We review pre-clinical and clinical findings from ultrasound-mediated BBB opening and drug delivery studies and outline current therapeutic ultrasound devices and technologies designed for this purpose.

Leveraging advances in chemistry to design biodegradable polymeric implants using chitosan and other biomaterials

The metamorphosis of biodegradable polymers in biomedical applications is an auspicious myriad of indagation. The utmost challenge in clinical conditions includes trauma, organs failure, soft and hard tissues, infection, cancer and inflammation, congenital disorders which are still not medicated efficiently. To overcome this bone of contention, proliferation in the concatenation of biodegradable materials for clinical applications has emerged as a silver bullet owing to eco-friendly, nontoxicity, exorbitant mechanical properties, cost efficiency, and degradability. Several bioimplants are designed and fabricated in a way to reabsorb or degrade inside the body after performing the specific function rather than eliminating the bioimplants. The objective of this comprehensive is to unfurl the anecdote of emerging biological polymers derived implants including silk, lignin, soy, collagen, gelatin, chitosan, alginate, starch, etc. by explicating the selection, fabrication, properties, and applications. Into the bargain, emphasis on the significant characteristics of current discernment and purview of nanotechnology integrated biopolymeric implants has also been expounded. This robust contrivance shed light on recent inclinations and evolution in tissue regeneration and targeting organs followed by precedency and fly in the ointment concerning biodegradable implants evolved by employing fringe benefits provided by 3D printing technology for building tissues or organs construct for implantation.

Drug-Eluting Stents and Balloons-Materials, Structure Designs, and Coating Techniques: A Review

Controlled drug delivery is a matter of interest to numerous scientists from various domains, as well as an essential issue for society as a whole. In the treatment of many diseases, it is crucial to control the dosing of a drug for a long time and thus maintain its optimal concentration in the tissue. Heart diseases are particularly important in this aspect. One such disease is an obstructive arterial disease affecting millions of people around the world. In recent years, stents and balloon catheters have reached a significant position in the treatment of this condition. Balloon catheters are also successfully used to manage tear ducts, paranasal sinuses, or salivary glands disorders. Modern technology is continually striving to improve the results of previous generations of stents and balloon catheters by refining their design, structure, and constituent materials. These advances result in the development of both successive models of drug-eluting stents (DES) and drug-eluting balloons (DEB). This paper presents milestones in the development of DES and DEB, which are a significant option in the treatment of coronary artery diseases. This report reviews the works related to achievements in construction designs and materials, as well as preparation technologies, of DES and DEB. Special attention was paid to the polymeric biodegradable materials used in the production of the above-mentioned devices. Information was also collected on the various methods of producing drug release coatings and their effectiveness in releasing the active substance.

Recent advances in celluloses and their hybrids for stimuli-responsive drug delivery

The limitations of existing drug delivery systems (DDS) such as non-specific bio-distribution and poor selectivity have led to the exploration of a variety of carrier platforms to facilitate highly desirable and efficient drug delivery. Stimuli-responsive DDS are one of the most versatile and innovative approach to steer the compounds to the intended sites by exploiting their responsiveness to a range of various triggers. Preparation of stimuli-responsive DDS using celluloses and their derivatives offer a remarkable advantage over conventional polymer materials. In this review, we highlight on state-of-art progress in developing cellulose/cellulose hybrid stimuli-responsive DDS, which covers the preparation techniques, physicochemical properties, basic principles and, mechanisms of stimuli effect on drug release from various types of cellulose based carriers, through recent innovative investigations. Attention has been paid to endogenous stimuli (pH, temperature, redox gradient and ionic-strength) responsive DDS and exogenous stimuli (light, magnetic field and electric field) responsive DDS, where the cellulose-based materials have been extensively employed. Furthermore, the current challenges and future prospects of these DDS are also discussed at the end.

Sustainable and rapidly degradable poly(butylene carbonate-co-cyclohexanedicarboxylate): influence of composition on its crystallization, mechanical and barrier properties

Sustainable and fast biodegradable PBCCEs copolyesters have potential applications in green packaging and tissue engineering.

Implantable Polymeric Drug Delivery Devices: Classification, Manufacture, Materials, and Clinical Applications

The oral route is a popular and convenient means of drug delivery. However, despite its advantages, it also has challenges. Many drugs are not suitable for oral delivery due to: first pass metabolism; less than ideal properties; and side-effects of treatment. Additionally, oral delivery relies heavily on patient compliance. Implantable drug delivery devices are an alternative system that can achieve effective delivery with lower drug concentrations, and as a result, minimise side-effects whilst increasing patient compliance. This article gives an overview of classification of these drug delivery devices; the mechanism of drug release; the materials used for manufacture; the various methods of manufacture; and examples of clinical applications of implantable drug delivery devices.

Biocompatibility, biodegradation and excretion of polylactic acid (PLA) in medical implants and theranostic systems

Polylactic acid (PLA) is the most commonly used biodegradable polymer in clinical applications today. Examples range from drug delivery systems, tissue engineering, temporary and long-term implantable devices; constantly expanding to new fields. This is owed greatly to the polymer's favorable biocompatibility and to its safe degradation products. Once coming in contact with biological media, the polymer begins breaking down, usually by hydrolysis, into lactic acid (LA) or to carbon dioxide and water. These products are metabolized intracellularly or excreted in the urine and breath. Bacterial infection and foreign-body inflammation enhance the breakdown of PLA, through the secretion of enzymes that degrade the polymeric matrix. The biodegradation occurs both on the surface of the polymeric device and inside the polymer body, by diffusion of water between the polymer chains. The median half-life of the polymer is 30 weeks; however, this can be lengthened or shortened to address the clinical needs. Degradation kinetics can be tuned by determining the molecular composition and the physical architecture of the device. Using L- or D- chirality of the LA will greatly slow or lengthen the degradation rates, respectively. Despite the fact that this polymer is more than 150 years old, PLA remains a fertile platform for biomedical innovation and fundamental understanding of how artificial polymers can safely coexist with biological systems.

Microenvironmental Control of MUC1 Aptamer-Guided Acid-Labile Nanoconjugate within Injectable Microporous Hydrogels

Although aptamers are well-known as cell-specific membrane biomarkers for tumor-targeted therapy, it is important to avoid their degradation by nucleases in vivo. In this study, we developed a MUC1 aptamer-doxorubicin nanoconjugate (APT-DOX) through an acid-labile linkage and embedded APT-DOX into a thermosensitive hydrogel for antitumor therapy. The hydrogels exhibit a sol-gel transition upon intratumoral injection, resulting in the protection and controlled release control of APT-DOX with the shielding of the gel network. Moreover, the released APT-DOX was prone to be enriched at the tumor cells due to specific intracellular transport by the overexpressing MUC1 protein; however, APT-DOX regained the free DOX form via the rupture of the linkage under tumor cells lysosome acidic conditions and achieved increased concentration in the nucleus for antitumor treatment.

Near-infrared light-responsive nanomaterials for cancer theranostics

Early diagnosis and effective cancer therapy are required, to properly treat cancer, which causes more than 8.2 million deaths in a year worldwide. Among various cancer treatments, nanoparticle-based cancer therapies and molecular imaging techniques have been widely exploited over the past decades to overcome current drawbacks of existing cancer treatments. In particular, gold nanoparticles (AuNPs), carbon nanotubes (CNTs), graphene oxide (GO), and upconversion nanocrystals (UNCs) have attracted tremendous attention from researchers due to their near-infrared (NIR) light-responsive behaviors. These nanomaterials are considered new multifunctional platforms for cancer theranostics. They would enable on-demand control of drug release or molecular imaging in response to a remote trigger by NIR light exposure. This approach allows the patient or physician to adjust therapy precisely to a target site, thus greatly improving the efficacy of cancer treatments, while reducing undesirable side effects. In this review, we have summarized the advantages of NIR light-responsive nanomaterials for in vivo cancer treatments, which includes NIR triggered photothermal therapy (PTT) and photodynamic therapy (PDT). Furthermore, recent developments, perspectives, and new challenges of NIR light-responsive nanomaterials are discussed for cancer theranostic applications.

Biocomputing, Biosensing and Bioactuation Based on Enzyme Biocatalyzed Reactions

The focus of this review paper is on the design and implementation of smart ‘Sense-and-Treat’ systems using enzyme-biocatalytic systems. These systems were used to perform biomolecular computing and they were functionally integrated with signal responsive materials aiming towards their biomedical use. Electrode interfaces, functionalized with signal-responsive materials, find applications in biocomputing, biosensing, and, specifically, triggered release of bioactive substances. ‘Sense-and-Treat’ systems require multiple components working together, including biosensors, actuators, and filters, in order to achieve closed-loop and autonomous operation. In general, biochemical logic networks were developed to process single biochemical or chemical inputs as well as multiple inputs, responding to nonphysiological (for concept demonstration purposes) and physiological signals (for injury detection or diagnosis). Actuation of drug-mimicking release was performed using the responsive material iron-cross-linked alginate with entrapped biomolecular species, responding to physical, chemical or biochemical signals.

Aptamer-incorporated hydrogels for visual detection, controlled drug release, and targeted cancer therapy

Hydrogels are water-retainable materials, made from cross-linked polymers, that can be tailored to applications in bioanalysis and biomedicine. As technology advances, an increasing number of molecules have been used as the components of hydrogel systems. However, the shortcomings of these systems have prompted researchers to find new materials that can be incorporated into them. Among all of these emerging materials, aptamers have recently attracted substantial attention because of their unique properties, for example biocompatibility, selective binding, and molecular recognition, all of which make them promising candidates for target-responsive hydrogel engineering. In this work, we will review how aptamers have been incorporated into hydrogel systems to enable colorimetric detection, controlled drug release, and targeted cancer therapy.

Biodegradable 'intelligent' materials in response to chemical stimuli for biomedical applications

BACKGROUND

Biodegradable stimuli-responsive materials, which exhibit large and sharp physical-chemical changes in response to small physical or chemical stimuli, are attracting increasing interests because of their potential applications in biomedical fields, such as transient implants, drug delivery carriers, and tissue engineering scaffolds. Our previous review (see page 493 of issue 4) summarized those biodegradable 'intelligent' materials that respond to physical stimuli, such as temperature, ultrasound, and magnetic field. Biodegradable 'intelligent' materials that could respond to chemical stimuli, such as pH and specific molecules, have also been studied intensively and significant progress in this field has been achieved. As a single stimulus-responsive property would limit practical application, multi-stimuli-responsive materials are receiving increasing interest and considerable attention.

OBJECTIVE/METHODS

This review summarizes the development of biodegradable 'intelligent' materials in response to chemical stimuli and to dual stimuli; their potential biomedical applications are also introduced. A detailed analysis of publications and patents on such materials in recent years is presented.

RESULTS/CONCLUSION

Most of biodegradable stimuli-responsive materials are currently still at a developmental research stage. Further work is required to improve the responsive properties between the materials and the biological environments, so that the clinical applicability of such devices could be successful. We hope that our review will be helpful in the future development of new stimuli-responsive biodegradable polymers or polymeric systems that can be used reliably in real-life applications.

Incorporation of α-Amylase Enzyme and a Bioactive Filler into Hydrophilic, Partially Degradable, and Bioactive Cements (HDBCs) as a New Approach To Tailor Simultaneously Their Degradation and Bioactive Behavior

Hydrophilic, partially degradable, and bioactive cements (HDBCs) are starch-containing cements intended to degrade partially in the human body and, in so doing, allow for bone ingrowth inside the pores formed during degradation. Therefore, the study of degradation and bioactivity behavior was performed to assess the suitability of the current HDBCs formulations to achieve those aims. The degradation profile of HDBCs was studied under different conditions, including incubation in phosphate-buffered saline (PBS) and PBS supplemented with alpha-amylase at different concentrations. Thermostable alpha-amylase was also added to some formulations to allow control of the degradation rate and its extent. In a second stage the simultaneous phenomena of enzymatic degradation and bioactivity (both in vitro) was studied. We observed that the degradation of starch present in HDBCs can be easily controlled by the amount of alpha-amylase added to the cement and high values of degradation may be achieved if high enough quantities of enzyme are incorporated. However, the maximum degradation extent is much more dependent on the total amount of starch present in the formulation than on the amount of enzyme added to it: for full pore connectivity, the amount of starch should be higher than the percolation threshold for a 3D specimen. Nonetheless, calcium phosphate was able to nucleate and spread in inner pores of the cement, formed due to degradation, if they were interconnected. For a more thorough covering of the pores with calcium phosphates the amount of starch present in HDBCs should be increased to be higher than the percolation threshold.