Design of Coiled-Coil Protein Nanostructures for Therapeutics and Drug Delivery.

The provision of appropriate postoperative analgesia should be as important to modern surgery as is intraoperative anesthesia. Potent analgesics, such as morphine, have been available for several hundred years, yet our efficacy in treating acute postoperative pain was until recently abysmal. As late as 1983, 41% of patients rated their pain control inadequate after surgery [1]. The use of self-titration of an analgesic drug to provide postoperative pain management was first achieved in 1968 [2]. The ability to provide self-titration was dependent on developing an appropriate analgesic drug delivery device. It took years for industry to adopt this concept and to develop a commercial device. It also took physicians some time to recognize the utility of this approach to postoperative pain. It did not take patients long to demand patient-controlled analgesia (PCA), which is now widely practiced. There is no doubt that PCA provided a major step forward in the management of acute postoperative pain. Why has PCA provided a more satisfied patient with improved pain relief? Pain is a very subjective sensation, the effective concentration required for pain relief is extremely variable between patients (pharmacodynamic variability) as well as within patients, and lastly, any given dose will result in a different concentration in each individual due to the unique disposition of the drug in the individual (pharmacokinetic variability). In addition, safety is an issue. Potent opiate analgesics have a very narrow therapeutic margin, with doses exceeding the therapeutic concentration producing significant adverse effects (toxicity). Thus, the objective of any analgesic delivery system is to allow safe individual titration of drug dose so patients can maintain themselves within their own therapeutic window. PCA achieves this objective. There are, however, some theoretical disadvantages to PCA. Pain is the most intense soon after awakening. Thus, the required concentration of the analgesic is initially high. To attain an effective concentration requires some form of a large initial dose to fill the volume of distribution. To avoid exceeding the therapeutic concentration, multiple small doses of the opiate are given until adequate analgesia is obtained. For opiates like morphine, which equilibrate slowly from the blood to the brain and receptor, this equilibration period can take several hours. Also, due to redistribution and elimination, once the peak effect of the drug is achieved, drug concentration is continuously decreasing. Thus, PCA does not totally avoid the peaks and valleys of intermittent intramuscular injection, but simply makes them smaller. While PCA has been widely accepted clinical practice, further technologic developments are occurring to further improve drug delivery. Certainly, on a theoretical basis, it is ideal to administer drugs to a target effect (i.e., the clinician sets the targeted effect, e.g., degree of neuromuscular blockade, and the delivery system simply adjusts the dosing rate to achieve this monitored response). Unfortunately, neither anesthesia nor analgesia has readily measurable or quantifiable end-points. Thus, the next best is to be able to administer the drug to an effective concentration. By using pharmacokinetic parameters derived from the disposition of the drug, it is possible to program a computer so that it calculates the dosing regimen necessary to achieve the target plasma concentration (thereby automatically providing the initial loading of the drug) [3]. The efficacy of such devices for the administration of intravenous drugs during anesthesia has been evaluated in many studies over the past 15 yr [3]. Using pharmacokinetic-pharmacodynamic modeling, it is also possible to program the drug delivery device not only to target a plasma concentration but also to target an effect site concentration (i.e., the concentration that is in equilibration with the site of drug effect, e.g., the opiate receptor) [4,5]. This prevents much of the time delay that occurs as the plasma concentration equilibrates with drug receptors in the brain. For example, if a target plasma concentration of fentanyl is selected, it will take approximately 20 min before the full effect of this concentration is observed, whereas if a target effect site concentration is selected the full effect will occur within 3-5 min. Such computer controlled infusion devices [computer assisted continuous infusion (CACI) [6]] can be programmed to almostly instantaneously produce a desired effect concentration and then maintain this concentration. It is a logical step to combine PCA with CACI devices so that patients can rapidly attain and maintain an effective concentration of the analgesic. In this issue of Anesthesia & Analgesia, van den Nieuwenhuyzen et al. [7], although not the first to use such a system, are the first to try to compare the possible advantages of CACI-PCA (referred to as CCIA in their paper) with those of conventional PCA for postoperative pain management. Their results strongly support the superiority of CACI-PCA over conventional patient-controlled administration. This is based on a more rapid achievement of satisfactory analgesia, the time patients spent at the desired level on the visual analog pain scale (VAS; VAS less than 3), and the total number of doses requested by the patient. The CACI-PCA results favoring target-controlled infusion for PCA need to be carefully reviewed. Unfortunately, the authors chose to compare two different drugs using two different delivery modes. It is difficult to determine whether the advantageous results were due to the drug or the delivery system. Alfentanil has a very rapid onset of effect as evidenced by its ke0 (the ke0 represents the rate of equilibration between the plasma and the effect site). The ke0 for morphine has not been established, but is considered to be considerably longer than that of alfentanil. The more rapid onset of effective analgesia with target-controlled alfentanil could largely be explained by these differences in ke0 rather than the drug delivery system. Similarly, it is noted that the greatest difference in the time period for which there was a VAS of greater than 3 between the two groups was from 0 to 8 h. This again may simply be explained by the slower onset of effective analgesia with morphine compared to alfentanil, rather than the delivery system. In addition, the incremental doses delivered with each demand may not have been truly equally efficacious; thus, it may have required two demands for morphine to provide the same degree of analgesic relief as one demand for alfentanil. This difference would then readily explain the differences in demand and continued differences in time above a VAS of 3 between the two groups. Of interest and noted by van den Nieuwenhuyzen et al., PCA alfentanil has not provided effective postoperative pain management when given with a conventional PCA device. The authors have demonstrated that when alfentanil is administered using target CACI-PCA for postoperative pain management, it is definitely superior to conventional PCA morphine in providing postoperative pain relief. From this we can infer that through the utilization of CACI-PCA alfentanil becomes a more suitable opiate for postoperative pain management. One of the primary advantages of CACI drug delivery for postoperative analgesia is that it will maintain the drug level within the therapeutic window for longer periods of time. This argument should similarly hold true when using a low-dose continuous infusion in combination with PCA. The combination of a continuous infusion plus PCA has resulted in a greater number of side effects and greater opiate use but no greater pain relief [8]. A possible explanation for this is that pain, after surgery, does not remain constant, but rather is constantly changing. The advantage of a standard PCA regimen is that no drug is being delivered when pain is decreasing or is minimal. It would therefore seem that the ideal delivery system should rapidly achieve an effective concentration and that this concentration should not necessarily be maintained, but should decrease over time to enable patients to keep themselves within their own changing therapeutic window. van den Nieuwenhuyzen et al. [7] in this study creatively addressed this problem by forcing the target-controlled concentration to decrease after 2 h if no patient demand had been made. Is 2 h an appropriate time interval to wait? CACI drug delivery usually uses a single pharmacokinetic set to represent the entire patient population. van den Nieuwenhuyzen et al. demonstrated that the pharmacokinetics of Maitre et al. [9] provided minimal bias and a low-median absolute performance error. This does not exclude the possibility that in any individual patient, over a 2-h period, the target concentration is increasing with the possibility of significant respiratory depression. When evaluating patients on morphine PCA, the authors' philosophy is to adjust the PCA dose to provide one to two patient-demanded doses per hour. Thus, to wait 2 h without a demand prior to allowing the concentration to decrease may be to wait too long. Fortunately, a CACI drug delivery system can be programmed to start decreasing the target concentration at any specified time. Another feature of CACI-PCA that needs to be addressed is the size of the maintenance dose. Most potent opiates have a very steep concentration effect, so it will be necessary to establish appropriate and safe increments in opiate concentration with each demand. Thus, it is important to first confirm the optimal settings for a CACI delivery system when used in the patient-controlled mode, and then compare this to the traditional bolus method of patient-controlled analgesia using the same drug. The use of target-controlled drug delivery in a postoperative setting is relatively new. CACI has established itself as an important tool for the intravenous administration of drugs during anesthesia. As a drug delivery system, CACI is akin to the calibrated vaporizer, which is accepted as the standard delivery system for volatile anesthetics. CACI drug delivery has also proven to be more efficacious than intermittent bolus administration and at least equal to a manual infusion system [10]. As a tool CACI has enabled anesthesiologists to define the concentration effect relationship of drugs used in anesthesia, as well as the effect resulting from the interaction between intravenous drugs providing anesthesia [3]. In addition, CACI has enhanced our understanding of the pharmacokinetic and pharmacodynamic principles related to intravenous administration of anesthetic drugs. Like the concept of PCA, target-controlled drug delivery is dependent on having an accessible device. This is largely dependent on industry embracing this concept and providing a commercial device. The paper by van den Nieuwenhuyzen et al. [7] further demonstrates the use and potential of target-controlled drug delivery within our speciality. We predict with certainty and enthusiasm that, when industry and the regulatory agencies produce a CACI device, it will be widely accepted as another step forward in the never-ending quest to optimize patient care.

Purpose:A detailed study of the physicochemical properties of SMILE-derived lenticules and evaluation of their drug delivery after loading with silver nanoparticles (AgNPs).Methods:The lenticules were decellularized and modified with crosslinking concentrations of 0.01 (0.01E/L), 0.05 (0.05E/L), and 0.25 (0.25E/L) mmol N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) per mg lenticule at 5:1 carbodiimide/N-hydroxysuccinimide (EDC/NHS) ratios. The degree of swelling, light transmittance, biomechanical properties, and stability of the non-crosslinked decellularized lenticules (DLs), 0.01E/L, 0.05E/L, and 0.25E/L were measured and characterized using Fourier transform infrared spectroscopy and transmission electron microscopy with non-crosslinked non-decellularized lenticules as controls. DLs, 0.01E/L, 0.05E/L, and 0.25E/L were soaked in AgNPs for 24 hours, and the concentration of the drug released was measured.Results:There was no significant difference in the degree of swelling between the groups (P > 0.05). The light transmittance of the lenticules did not change after decellularization and crosslinking and decreased after loading with AgNPs. Non-decellularized lenticules biodegraded within 108 to 120 hours, and the other groups biodegraded within 96 to 108 hours in vitro. The 0.01E/L had the highest tensile strength. The absorption peak intensity ratio of the amide I band and the amide II band decreased, and the arrangement of collagen fibers was more compact in crosslinked decellularized lenticules. The 0.01E/L had the highest cumulative drug release (3.4 ± 0.91 μg).Conclusions:Crosslinking decellularization improved the biomechanical properties and resistance to water absorption of lenticules, increased covalent bonds between collagen fibers, and improved drug delivery. Crosslinked decellularized lenticules can be used as a new corneal patch material and drug delivery carrier for drug AgNPs.

Mechanisms and biomaterials in pH-responsive tumour targeted drug delivery: A review

Self-assembly of molecules is increasingly utilized in the design and development of novel materials for various chemical and biomedical applications. Amyloid fibrils, traditionally associated with neurodegenerative diseases, make up a class of biomaterials formed through the self-assembly of peptides and proteins. The excellent stability and biocompatibility of cross-β-sheet nanostructured amyloid fibrils make them promising biomaterials for therapeutic delivery and immunomodulation. Recent studies have demonstrated the ability of amyloid fibrils to encapsulate small molecules, support receptor-specific targeting through surface functionalization, and enable environmentally responsive drug release. Amyloid-based scaffolds have also shown notable potential in vaccine development and the controlled delivery of checkpoint inhibitors. Current research aims to hybridize amyloid-based scaffolds with commonly used drug delivery tools, such as liposomes and hydrogels, to further enhance therapeutic efficacy while minimizing toxicity. In immunological applications, amyloid fibrils serve as both carriers and adjuvants, promoting antigen presentation and sustained immune activation. This review provides an overview of current progress in the design and application of functional amyloid nanostructures for targeted drug delivery and immunotherapy. The growing understanding of engineered amyloid-based drug delivery platforms may drive the development of precision medicine and support the design of innovative biomaterials.

Monoclonal antibodies (mAb) selectively recognizing tumor surface antigens are an important and evolving approach to targeted cancer therapy. One application of therapeutic mAbs is drug targeting via mAb-drug conjugate (ADC) technology. Identification of mAbs capable of internalizing following antigen binding has been accomplished by tracking decline of surface-bound mAb or by internalization of a secondary mAb linked to a toxin. These methods may not be sufficiently sensitive for screening nor wholly predictive of the mAbs' capacity for a specific drug delivery. We have developed a highly selective and sensitive method to detect mAbs for cell internalization and drug delivery. This system uses secondary anti-human or anti-murine mAbs conjugated to the high-potency drug monomethyl auristatin E (MMAE) via a highly stable, enzymatically cleavable linker. Prior studies of this drug linker technology demonstrated internalization of a primary ADC leads to trafficking to lysosomes, drug release by lysosomal cathepsin B, and ensuing cell death. A secondary antibody--drug conjugate (2 degrees ADC) capable of binding primary mAbs bound to the surface of antigen-positive cells has comparable drug delivery capability. The system is sufficiently sensitive to detect internalizing mAbs in nonclonal hybridoma supernatants and is predictive of the activity of subsequently produced primary ADC. Because of their high extracellular stability, the noninternalized 2 degrees ADC are 100--1000-fold less toxic to cells over extended periods of time, permitting an assay in which components can be added without need for separate wash steps. This homogeneous screening system is amenable to medium-throughput screening applications and enables the early identification of mAbs capable of intracellular trafficking for drug delivery and release.

Nanotechnology in drug delivery has been manifested into nanoparticles that can have unique properties both in vitro and in vivo, especially in targeted drug delivery to tumors. Numerous nanoparticle formulations have been designed and tested to great effect in small animal models, but the translation of the small animal results to clinical success has been limited. Successful translation requires revisiting the meaning of nanotechnology in drug delivery, understanding the limitations of nanoparticles, identifying the misconceptions pervasive in the field, and facing inconvenient truths. Nanoparticle approaches can have real impact in improving drug delivery by focusing on the problems at hand, such as enhancing their drug loading capacity, affinity to target cells, and spatiotemporal control of drug release.

The use of nanosized materials changes the way in which drugs are handled by the body and offers opportunities to improve drug delivery. The physiological mechanisms controlling the distribution of nanosized materials (enhanced permeability and retention effect, cellular uptake pathways and opsonisation/elimination of nanoparticles) are described. Two different nanosized drug delivery systems are considered; drug delivery and DNA delivery. The deficiencies of currently available biodegradable polymers for preparation of drug containing nanoparticles are mainly the amount of drug that can be incorporated and the rapid rate of drug release. The development of new biodegradable polymers which can interact with the drug and so significantly increase drug loading and decrease the rate of drug release are outlined. DNA delivery necessitates overcoming a variety of biological barriers. We are developing polyelectrolyte complexes of DNA with cationic polyamidoamines (PAA) as a delivery system. Complexing PAA with DNA results in good transfection of cells in vitro. However, in vivo, a more complex arrangement of PAA, Polyethylene glycol-PAA copolymers, DNA and the use of ligands will be required. Despite these efforts, further developments will be needed in nanotechnology for both drug and DNA nanoparticle delivery systems to achieve our clinical objectives.

Polymeric micelles (PMs) have been the most popular and promising topic of many researches in the field of drug delivery and targeting for the past two decades. Polymeric micelles are the selfassembled nano-sized colloidal particles which are made up of amphiphilic block copolymers i.e. polymers consisting of hydrophobic block and hydrophilic block. In this highlight, we give an overview of the structure of micelles and polymeric micelles followed by a summary of the methods used for their preparation. We then focus on several kinds of PMs based on intermolecular forces such as polyion complex micelles (PICMs), non-covalently connected micelles (NCCMs) and recently developed smart polymeric assemblies which can respond to the application of external stimuli such as a change in temperature, pH, redox and light to afford novel nanomaterials. The types of polymers used in the preparation of PMs have also been highlighted so as to facilitate its use in drug delivery and targeting. These polymeric micelles nanocarriers have applications in drug delivery primarily such as anticancer therapy, to the brain to treat neurodegenerative diseases, antifungal agents, stimuli-responsive nanocarriers for drug and gene delivery, ocular drug delivery. Targeted drugs will hopefully reduce adverse reactions by limiting their action to cancer tissue only. Finally, this review broadly presents the basic aspects of PMs which help in delivery and targeting of actives with its recent advancements and applications. Key words: micelles, polymeric micelles, block copolymer, stimuli sensitivity

Aim: The rational design of a fluorescence imaging-guided, highly efficient multiresponsive delivery system is important for improving drug delivery efficiency. Materials and methods: Herein, pH/H2O2-responsive polyhedral oligomeric silsesquioxane (POSS) molecule functionalized 4-(phenyl(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)amino)benzaldehyde (OTB) copolymer (PEG-POSS-OTB) was synthesized to encapsulate doxorubicin (DOX) for precise drug delivery. Results: The self-assembly fluorescent vesicles exhibited excellent pH/H2O2-responsive drug release properties under physiological conditions and efficient drug-targeting ability. In vitro, compared with the DOX group, PEG-POSS-OTB fluorescent vesicles exhibited improved drug delivery and reduced toxicity. Importantly, we performed a proof-of-concept study demonstrating that PEG-POSS-OTB fluorescent vesicles were a high-efficiency nanoassembly drug-delivery platform for improving drug delivery efficiency. In vivo studies demonstrated that PEG-POSS-OTB vesicles with enhanced stability could be used in targeted drug delivery and controlled intelligent release.

This review aims to address the significant challenges of treating central nervous system (CNS) disorders such as neurodegenerative diseases, strokes, spinal cord injuries, and brain tumors. These disorders are difficult to manage due to the complexity of disease mechanisms and the protective blood-brain barrier (BBB), which restricts drug delivery. Recent advancements in nanoparticle (NP) technologies offer promising solutions, with potential applications in drug delivery, neuroprotection, and neuroregeneration. By examining current research, we explore how NPs can cross the BBB, deliver medications directly to targeted CNS regions, and enhance both diagnostics and treatment. Key NP strategies, such as passive targeting, receptor-mediated transport, and stimuli-responsive systems, demonstrate encouraging results. Studies show that NPs may improve drug delivery, minimize side effects, and increase therapeutic effectiveness in models of Alzheimer's, Parkinson's, stroke, and glioblastoma. NP technologies thus represent a promising approach for CNS disorder management, combining drug delivery and diagnostic capabilities to enable more precise and effective treatments that could significantly benefit patient outcomes.

The unceasing efforts and improvement of drug delivery systems (DDSs) have been broadly researched to maximize therapeutic efficacy while curtailing undesirable side effects. Nanoparticle technology was recently shown to hold great promise for drug delivery applications in nanomedicine due to its favorable properties, such as better encapsulation, bioavailability, control release, and lower toxic effects. Regardless of the great progress in nanomedicine, there remain many limitations prior to widely being accepted for medical application. To overcome these limitations, advanced nanoparticles for drug delivery have been developed to enable the spatially and temporally controlled release of drugs in response to specific stimuli at disease sites. An ideal drug delivery system should be able to localize a drug specifically and directly to its target. This is particularly important when drugs made by traditional manufacturing methods are hydrophobic and their solvents are toxic. Nanotechnology promises to improve drug delivery system design and targeting. Nanostructured drugs or delivery carriers allow the continuous and controlled release of therapeutic drugs to maintain drug levels to a desired extent. The size of nanoparticles ranges from 10 to 200 nm, about the size of a protein. Because of their small size, nanoparticles can readily interact with biomolecules on the cell surface or inside cell allowing these nanoparticles to penetrate tissues in depth with a high level of specificity. This chapter discusses an overview of nanoparticulate systems that can be used as a potential drug delivery carriers and focuses on the potential applications of nanoparticles in various biomedical fields for improving human health care.

Chapter 2 - Design and construction of bioinspired supramolecular self-assembled nanostructures

Effective remedy to gastrointestinal (GI) side effects caused by poorly water-soluble drugs remains a challenge. Researching for novel techniques to reduce these side effects and increase patient adherence to medical treatment is of interest. The current study aims to develop an innovative nano-sized gastro-retentive drug delivery for better management of poorly water-soluble drugs. A non-disintegrating ibuprofen-asymmetric membrane floating nanoparticle (Ibuprofen-AMFNP) was prepared by phase inversion technique to increase the gastric residence of the drug. Powder characterization, solubility, in vitro buoyancy, effect on in vivo inflammatory markers, and polymer diffusibility studies were conducted on the prepared formulation. All UV-spectrophotometric analysis was accomplished through a fiber optic system. The prepared Ibuprofen-AMFNPs were in the nano range of 114.45nm ±1.31nm. The formulation was buoyant for 12h in the dissolution media indicating increased gastric residence, had better solubility and powder characteristics compared to the pure drug. Scanning electron microscopy revealed an outer non-porous and inner porous asymmetric membrane. Ibuprofen-AMFNP followed Higuchi drug release kinetics (p=0.9925) and had a Fickian diffusion release mechanism (n=0.05). Polymer diffusibility study showed that the 24h stored formulation had faster drug release with no lag time (-923.08nm/h) compared to a fresh formulation (2526.32nm/h). The prepared nano-formulation showed a higher percentage of anti-inflammatory (85.144%) effect compared to the pure drug (78.336%). Ibuprofen-AMFNP is envisioned to help reduce drug-related GI side effects, improve drug delivery, and thereby increase patient adherence to medical treatment.

Polymeric micelles are effective for drug delivery but often face instability, low drug loading capacity (DLC), and premature drug leakage. Herein, we report that disubstituted γ-amide functionalized ε-caprolactone (ε-CL) monomers double the substituent density per polymeric unit, enhancing micelle properties and improving drug delivery applications. Three hydrophobic ε-CL monomers with two propyl groups, two benzyl groups, and a combination of propyl and benzyl groups were synthesized. The obtained monomers were polymerized by ring-opening polymerization using poly(ethylene glycol) (PEG) as a macroinitiator and the hydrophilic block. The synthesized copolymers successfully self-assembled to form micelles, and doxorubicin (DOX) was loaded into all micelles. Poly(ethylene glycol)-b-poly(N-propyl-N-benzyl-7-oxopane-4-carboxamide) (PEG-b-PBnPyCL) exhibited 7.33 wt % DLC with pH-responsive drug release in acidic conditions. In addition, the DOX-loaded micelles of PEG-b-PBnPyCL exhibited nearly 20% cell viability in MDA-MB-231 cancer cells. These results contribute to advancing polymeric micelles as drug carriers with clinical translation potential.

Cervical cancer is the second most common cancer in women. Standard treatment options available for cervical cancer include chemotherapy, surgery and radiation therapy associated with their own side effects and toxicities. Tumor-targeted delivery of anticancer drugs is perhaps one of the most appropriate strategies to achieve optimal outcomes from the treatment and improve the quality of life. Recently nanocarriers based drug delivery systems owing to their unique properties have been extensively investigated for anticancer drug delivery. In addition to that addressing the anatomical significance of cervical cancer, various local drug delivery strategies for the cancer treatment are introduced like: gels, nanoparticles, polymeric films, rods and wafers, lipid based nanocarrier. Localized drug delivery systems allow passive drug targeting results in high drug concentration at the target site. Further they can be tailor made to achieve both sustained and controlled release behavior, substantially improving therapeutic outcomes and minimizing side effects. This review summarizes the meaningful advances in drug delivery strategies to treat cervical cancer.