Delivery Devices Research Articles

Development of aminolyzed polylactic acid-based porous films for pH-responsive sustained drug delivery devices

Biomaterial-based drug-carrying systems have scored enormous focus in the biomedical sector. Poly(lactic acid) (PLA) is a versatile material in this context. A porous and hydrophilic PLA surface can do this job better. We aimed to synthesize pH-responsive PLA-based porous films for uptaking and releasing amikacin sulfate in the aqueous media. The native PLA lacks functional/polar sites for the said purpose. So, we tended to aminolyze it for tailored physicochemical and surface properties. The amino (−NH2) group density on the treated films was examined using the ninhydrin assay. Electron microscopic analyses indicated the retention of porous morphology after aminolysis. Surface wettability and FTIR results expressed that the resultant films became hydrophilic after aminolysis. The thermal analysis expressed reasonable thermal stability of the aminolyzed films. The prepared films expressed pH-responsive behaviour for loading and releasing amikacin sulfate drug at pH 5.5 and 7.4, respectively. The drug release data best-fitted the first-order kinetic model based on Akaike information and model selection criteria. The prepared PLA-based aminolyzed films qualified as potential candidates for pH-responsive drug delivery applications. This study could be the first report on pH-responsive amikacin sulfate uptake and release on the swellable aminolyzed PLA-based porous films for effective drug delivery application.

Analysis of the Cross-Contamination of explosive canine training aids during manufacturing and storage

Explosive detecting canines should be trained using real explosive materials that have minimal contamination by other explosive odors to ensure accurate identification of potential threats. Therefore, the potential for cross-contamination between training aids is of importance. There are various storage methods in use by canine handlers, such as plastic and cloth bags, but these can lead to cross-contamination between training aids during storage. Alternatively, odor-permeable membrane devices (OPMD) may store training aides and be used as a delivery device. OPMDs allow for volatile compounds from the training aids to be released during training while helping to prevent contaminants from entering the device. However, the amount of contamination in a training aid upon receipt from a vendor is outside the control of canine handlers. To test the initial cross-contamination levels of training aids, 11 explosive materials were ordered from three different vendors. A 1-gram sample of each was collected and analyzed using gas chromatography – mass spectrometry. In several cases, explosive materials that are commercially available already exhibit elevated levels of contamination. This indicates that training aids must be acquiring contamination during manufacturing and/or storage at the vendor facility. The cross-contamination of explosive canine training aids stored in OPMDs was further evaluated and compared to traditional storage methods by storing various combinations of storage containers with explosives and using activated charcoal strips to collect the volatile compounds. Only one type of storage container, a Velcro bag, showed evidence of contamination.

Design of a Closed-Loop Wireless Power Transfer System for an Implantable Drug Delivery Device

Design of a Closed-Loop Wireless Power Transfer System for an Implantable Drug Delivery Device

Digital health and health equity: How digital health can address healthcare disparities and improve access to quality care in Africa.

The healthcare industry is constantly evolving to bridge the inequality gap and provide precision care to its diverse population. One of these approaches is the integration of digital health tools into healthcare delivery. Significant milestones such as reduced maternal mortality, rising and rapidly proliferating health tech start-ups, and the use of drones and smart devices for remote health service delivery, among others, have been reported. However, limited access to family planning, migration of health professionals, climate change, gender inequity, increased urbanization, and poor integration of private health firms into healthcare delivery rubrics continue to impair the attainment of universal health coverage and health equity. Health policy development for an integrated health system without stigma, addressing inequalities of all forms, should be implemented. Telehealth promotion, increased access to infrastructure, international collaborations, and investment in health interventions should be continuously advocated to upscale the current health landscape and achieve health equity.

Development and characterization of 3D printed ethylene vinyl acetate (EVA) as drug delivery device for the treatment of overactive bladder

The overactive bladder is a condition characterized by a sudden urge to urinate, even with small volumes of urine present in the bladder. The current treatments available for this pathology consist on conservative approaches and the continuous administration of drugs, which when made by conventional methods has limitations related to the first pass metabolism, bioavailability, severe side effects, and low patient adherence to treatments, ultimately leading to low effectiveness. Within this context, the present work proposes the design, manufacture, and characterization of an intravesical implant for the treatment of overactive bladder pathology, using EVA copolymer as a matrix and oxybutynin as a drug. The fabrication of devices through two manufacturing techniques (extrusion and additive manufacturing by fused filament fabrication, FFF) and the evaluation of the implants through characterization tests was proposed. The usability and functionality were evaluated through simulated insertion of the device/prototype in a bladder model through catheter insertion tests. The safety and effectiveness of the devices was investigated from mechanical testing as well as drug release assays. Drug release assays presented a burst release in the first 24 h, followed by a release of 1.8 and 2.8 mg/d, totalizing 32 d. Mechanical tests demonstrated an increase in the stiffness of the specimens due to the addition of the drug, showing a change in maximum stress and strain at break. The released dose was higher than that usually presented when considering the oral administration route, showing the optimization of the development of this implant has the potential to improve the quality of life of patients with overactive bladder.

Formulation and Optimization of Intra Nasal Niosomal Gel of Kynurenic Acid: In Vitro in Vivo Characterization

Kynurenic acid's (KNA) inability to cross the blood brain barrier (BBB) severely limits its usage as a neuroprotective drug, despite the fact that it may have significant therapeutic effects in neurological illnesses. Drug delivery devices are one of the new avenues we're exploring as a means for KNA to enter the brain. Due to its low absorption when taken orally, medication formulation faces a significant hurdle. Here, nasal drug delivery has emerged as a popular alternate method for increasing medication bioavailability. In light of this, the current investigation set out to increase KNA bioavailability by means of an intranasal formulation based on niosomal technology. Rapid onset and evasion of first-pass metabolism are both offered by the nasal route, whereas niosomes protect hydrophilic medicines inside their core. For the purpose of determining entrapment efficiency, particle size, and in vitro drug release, niosomes were synthesized by combining lipid, nonionic surfactant, and cholesterol in distinct ratios. With a vesicle size of 248.51±1.54nm, the optimized niosomal formulation demonstrated a superior drug content (DC) of 98216±0.11% and an entrapment efficiency (EE) of 89.23±0.35. The formulation also contained cholesterol in an equal proportion (1:1). A value of 24 minutes was shown in the in vitro drug diffusion testing, indicating that the formulation exhibited prolonged activity. Gelation occurred at 37 ⁰C, which is the body's physiological temperature, and the optimum in situ gel, which contained 1:2 carbopol 934 and benzalkonium chloride, had a t90 value of 24 hours, indicating prolonged activity. In comparison to KNA oral suspension, the results showed that the KNA-loaded niosomal gel had a much higher relative bioavailability and improved drug penetration through the nasal mucosa

Complex cilia-generated flow of hybrid nanofluid with electroosmosis, viscous dissipation and slippage

In this study, we investigated how electroosmsis, viscous dissipation, and slippage affect the peristaltic flow of complex cilia-generated flow of hybrid nanofluid in a ciliated tube. The complex cilia-generated flow is characterized by a complex sinusoidal wave that transmits along the wall of the tube with a uniform speed having distinct amplitudes. The main objective of this work is to examine how this complex cilia on the wall drives the hybrid nanofluid flow under electroosmosis. The Helmholtz–Smoluchowski equation is used to model the electroosmosis, and the Poisson equation is solved analytically using the Debye-Huckel approximation. The lubrication approach is utilized to simplify the governing equations. The governing non-dimensional equations for hybrid nanofluid are solved exactly using the DSolve command of Mathematica. The results are presented graphically to accomplish the theoretical results from the complex-cilia wave evolution from the necessary flow parameters in an asymmetric tube. The study shows that increasing the electroosmotic parameter leads to an increase in the velocity profile at the boundary and a decrease in the middle of the tube. Conversely, the Helmholtz–Smoluchowski velocity parameter has the opposite effect. The Brinkman parameter increases the temperature of the hybrid nanofluid. The study also presents a graphical analysis of pressure rise and pressure gradient for various values of the parameters. The pressure rise against volumetric flow is rate and pressure gradient increases by increasing the electroosmotic parameter and Helmholtz-Smoluchowski parameter, while it decreases for increasing the velocity slip parameter. The streamlines are drawn to study the trapping phenomena of blood in the hybrid nanofluid flow in an asymmetric tube by the formation of bolus and the division of streamlines. It is observed that the size and number of bolus close to the artery walls increases for electroosmotic parameter while reverse behavior is observed for Helmholtz-Smoluchowski parameter. The tabular presentation of the heat transfer coefficient at the wall is presented. The current results can be used in bio mathematical models to control fluid flow through micro-channels and to investigate ways to cure artery blockages and cancer tumors in biomedicine. The study can also be used to design and optimize microfluidic devices for drug delivery, lab-on-a-chip devices, and other biomedical applications.

Synthesis of alternating copolymer PAspNa‐alt‐PAsp(Pr) for drug delivery system

AbstractAlternating copolymers (ACs) contain two distinct monomeric unit types dispersed in alternating order of hydrophilic block and hydrophobic block. ACs have extensive and versatile applications in both academia and industry, especially in drug delivery systems (DDS) due to their unique physical and chemical properties. In the present research, poly(β‐benzyl l‐aspartate) (PBLA) was prepared by ring‐opening polymerization of BLA‐NCA. The result obtained from GPC showed that PBLA was successfully synthesized with narrow weight distribution Mw/Mn = 1.055. The outcome of copolymer has the degree of polymerization (DP) of PBLA was 50 based on the 1H NMR spectroscopy. Further, alternating copolymer poly(aspartate‐sodium) alternating poly(aspartate‐R) (PAspNa‐alt‐PAsp(Pr)), which allows the installation of expected compounds into a polymer backbone of PBLA without unwanted side effects, was synthesized via 2 steps: (1) aminolysis by 0.5 fold primary amine to attach hydrophobic group and (2) hydrolysis slowly by NaOH solution to form the hydrophilic group on the side chain of the polymer. The novel alternating copolymer synthesized successfully in this study was expected to be a promising candidate for drug delivery devices.

MgAl2O4–C refractories with balanced properties for a delivery device used in the double-roll thin strip continuous casting

To realize the double-roll thin strip continuous casting process for the production of high-quality steels, it is necessary to seek a new type of refractory material tailored for delivery device employed in this process. Therefore, the present study aimed to design and prepare MgAl2O4–C refractories for this purpose as well as to study their physical and mechanical properties, thermal shock resistance, oxidation kinetics, and to perform molten steel experiments after pre-oxidation treatment. The results of the present study demonstrated that the specimens could maintain high mechanical and thermal shock properties even after pre-oxidation treatment. After pre-oxidation at 1100 °C/1 h, the cold compressive strength of the specimen reached 17.63 MPa, with a residual strength ratio (thermal shock resistance) of 77.99%. Analysis of oxidation kinetics based on the shrinking core model indicated an increase in the effective diffusion coefficient and complete oxidation time with higher pre-oxidation temperature. Pre-oxidation of MgAl2O4–C refractories has been shown to be effective in reducing carbon penetration into the molten steel from carbon-containing refractories, thus maintaining the stability of the molten steel composition. This effect was attributed to enhanced contact and wettability between the steel and refractories, an augmented thickness of the pre-oxidized decarburized layer, the formation of a dense magnesium oxide layer, and the emergence of the MgAl1·9Fe1O4 phase. Consequently, an MgAl2O4–C refractories designed for the delivery device was proposed along with anticipated applicability in the double-roll continuous casting process.

EDITORIAL: PIONEERING THE FUTURE OF HEALTHCARE THROUGH ADVANCES IN NOVEL DRUG DELIVERY SYSTEMS

With great delight and anticipation, I extend my heartfelt greetings to you as we commence a new venture with the latest release of the International Journal of Pharmacy and Integrated Health Sciences (IJPIHS). This issue is particularly noteworthy as it highlights the pivotal domains of Pharmaceutical Sciences, Clinical Pharmacy, and Drug Delivery Systems, demonstrating their significant influence on applications in healthcare.
 In the ever-evolving landscape of pharmaceuticals and healthcare, the quest for innovative drug delivery systems has emerged as a pivotal force, reshaping the dynamics of patient care and treatment outcomes. This editorial aims to shed light on the ground-breaking advancements in novel drug delivery systems, as we navigate the frontiers of the pharmaceutical industry in our pursuit of improved therapeutic efficacy and patient well-being. In recent years, the field of drug delivery has witnessed a paradigm shift, driven by a convergence of interdisciplinary research, technological breakthroughs, and a deep understanding of physiological processes. The International Journal of Pharmacy and Integrated Health Sciences is proud to contribute to this ongoing dialogue by showcasing the latest research and developments in novel drug delivery systems.
 One of the key challenges in traditional drug administration lies in achieving optimal drug concentrations at the target site while minimizing side effects. Novel drug delivery systems address this challenge by providing precise control over drug release kinetics, enhancing bioavailability, and enabling targeted delivery to specific tissues or cells. This not only maximizes therapeutic effects but also minimizes adverse reactions, thereby improving patient compliance and overall treatment outcomes.
 Nanotechnology has emerged as a frontrunner in this domain, offering unprecedented opportunities for designing advanced drug delivery platforms. Nanoparticles, liposomes, and micelles provide versatile carriers for drugs, allowing for controlled release and targeted delivery. These nanocarriers not only protect the drug from degradation but also facilitate its transport across biological barriers, opening new avenues for personalized medicine and tailored treatment strategies.
 As we delve into the articles featured in this issue of the International Journal of Pharmacy and Integrated Health Sciences, we invite our readers to explore the multifaceted world of novel drug delivery systems. From cutting-edge research on nanomedicine to the implementation of smart drug delivery devices, the diverse contributions in this journal underscore the transformative potential of these innovations in reshaping the future of healthcare. I want to convey my appreciation to the readers of IJPIHS for their ongoing support and active involvement with our journal. Your commitment to staying informed and exchanging knowledge fuels our relentless pursuit of excellence. Thank you for being part of this remarkable journey.

Comparison of Oxygen Delivery Devices in Postoperative Patients with Hypoxemia: An Open-labeled Randomized Controlled Study.

Acute hypoxemic respiratory failure is among the more commonly occurring complications in postoperative patients. Supplemental oxygen and addressing the primary etiology form the basis of its treatment. We conducted an open-labeled randomized control trial with 90 adult patients and compared three oxygen delivery vehicles (ODV), i.e., noninvasive ventilation (NIV), high-flow nasal cannula (HFNC), and venturi mask (VM) in postoperative hypoxemic patients. The primary outcome variable was a change in the P/F ratio after 2 hours of use of ODV. It was observed that the change in P/F ratio after 2 hours was similar in all three ODV groups (p = 0.274). The mean values of the post-ODV P/F ratio were comparable with the pre-ODV P/F ratio in all three modalities. The P/F ratio after HFNC was 358.08 ± 117.95; after NIV was 357.60 ± 220.67; and after VM was 355.47 ± 101.90 (p = 0.997). Among HFNC, NIV, and VM, none of the devices proved superior to the other for use in postoperative hypoxemia. Mishra S, Kothari N, Sharma A, Goyal S, Rathod D, Meshram T, et al. Comparison of Oxygen Delivery Devices in Postoperative Patients with Hypoxemia: An Open-labeled Randomized Controlled Study. Indian J Crit Care Med 2024;28(3):294-298.

The intersection of mechatronics and precision engineering: Synergies and future directions

The convergence of mechatronics and precision engineering has sparked significant interest due to its potential to revolutionize various industries, ranging from manufacturing to healthcare. This review explores the synergies between these two domains and outlines potential future directions for research and application. Mechatronics, an interdisciplinary field combining mechanical engineering, electrical engineering, computer science, and control engineering, focuses on the design and development of intelligent systems with integrated sensing, actuation, and control capabilities. Precision engineering, on the other hand, emphasizes the fabrication of high-accuracy components and systems, often at micro or nanoscales, to meet stringent performance requirements. The intersection of mechatronics and precision engineering offers numerous synergistic opportunities. One such opportunity lies in the development of precision actuators and sensors with embedded intelligent control systems, enabling precise motion control and feedback mechanisms in complex systems. Furthermore, advancements in microfabrication techniques allow for the integration of sensors and actuators directly onto precision components, leading to miniaturized and efficient mechatronic systems. In manufacturing, this synergy facilitates the creation of highly automated and flexible production processes capable of producing intricate and high-quality products with minimal human intervention. In healthcare, it enables the development of precision medical devices for diagnostics, surgery, and drug delivery, enhancing patient outcomes and reducing the invasiveness of procedures. Future directions in this interdisciplinary field include exploring novel materials and manufacturing techniques to further improve the precision and performance of mechatronic systems. Additionally, advancements in artificial intelligence and machine learning are poised to enhance the autonomy and adaptability of mechatronic systems, enabling them to learn from data and adapt to changing environments in real-time. the intersection of mechatronics and precision engineering holds great promise for addressing complex engineering challenges and driving innovation across various industries. By leveraging their complementary strengths, researchers and engineers can unlock new opportunities to create smarter, more efficient, and more precise systems with transformative impacts on society.

A review on transdermal drug delivery system

Drugs that are applied topically are delivered using transdermal drug delivery devices. These are pharmaceutical preparations of varying sizes, containing one or more active ingredients, intended to be applied to the unbroken skin in order to deliver the active ingredient after passing through the skin barriers, and these avoid first pass metabolism. Today about 74% of drugs are taken orally and are not found effective as desired. To improve efficacy transdermal drug delivery system was emerged. A notable advantage of transdermal drug delivery compared to other methods like oral, topical, intravenous (IV), and intramuscular (IM) administration is its controlled release of medication into the patient's system. This controlled release is achieved either by using a porous membrane enclosing a medication reservoir or by utilizing the patient's body heat to melt thin layers of medication embedded in the adhesive. Despite its benefits, transdermal drug delivery has certain limitations due to the skin's effective barrier function. Only molecules with small sizes can efficiently permeate the skin and consequently be delivered through this method.

Relationships of hypoglycemia awareness, hypoglycemia beliefs, and continuous glucose monitoring glycemic profiles with anxiety and depression symptoms in adults with type 1 diabetes using continuous glucose monitoring systems

AimsTo evaluate relationships of hypoglycemia awareness, hypoglycemia beliefs, and continuous glucose monitoring (CGM) glycemic profiles with anxiety and depression symptoms in adults with type 1 diabetes (T1D) who use CGM. MethodsA cross-sectional survey and data collections were completed with 196 T1D adults who used CGM (59% also used automated insulin delivery devices (AIDs)). We assessed hypoglycemia awareness (Gold instrument), hypoglycemia beliefs (Attitudes to Awareness of Hypoglycemia instrument), CGM glycemic profiles, demographics, and anxiety and depression symptoms (Hospital Anxiety and Depression Scale). Analysis included simple and multiple linear regression analyses. ResultsLower hypoglycemia awareness, weaker “hypoglycemia concerns minimized” beliefs, stronger “hyperglycemia avoidance prioritized” beliefs were independently associated with higher anxiety symptoms (P < 0.05), with similar trends in both subgroups using and not using AIDs. Lower hypoglycemia awareness were independently associated with greater depression symptoms (P < 0.05). In participants not using AIDs, more time in hypoglycemia was related to less anxiety and depression symptoms (P < 0.05). Being female and younger were independently associated with higher anxiety symptoms, while being younger was also independently associated with greater depression symptoms (P < 0.05). ConclusionOur findings revealed relationships of impaired hypoglycemia awareness, hypoglycemia beliefs, CGM-detected hypoglycemia with anxiety and depression symptoms in T1D adults who use CGMs.

Evaluating how extended reality delivery device and preservice teacher major impact presence in immersive learning environments

Teacher education has begun to embrace the use of 360 videos to improve preservice teachers' (PSTs) engagement and immersion. While recent research on such use is promising overall, there are specific questions that have been left unanswered about the construct of presence in 360 videos. More specifically, research has yet to fully explore how video delivery devices and PST characteristics may impact presence. The purpose of this study was to respond to this gap in the literature by examining PST major, delivery device (ie, head mounted display vs. flat screen), and the interaction between the two in informing presence. A total of 93 PSTs watched 360 videos and then completed a questionnaire. Findings indicated that presence in head‐mounted displays was related to emotions and agency. Conversely, presence with flat screens meant familiarity and control. Moreover, PST major was a predictor of presence, suggesting that 360 videos should be personalized according to PST career and professional goals. Finally, the interaction effect of preparing to teach K‐12 mathematics and wearing a head‐mounted display had a negative and statistically significant effect on participants' perceived presence, thus indicating a non‐cumulative effect. Practitioner notesWhat is already known about this topic 360 videos are increasingly used to support preservice teacher training. 360 videos for teacher education foster immersion, presence, and noticing skills. What this paper adds Empirical evidence that 360 videos experienced with head‐mounted display facilitate agency and emotional involvement. Empirical evidence that 360 videos experienced with flat screens facilitate feelings of control. Data showed that preservice teachers' content area (math) was a positive predictor of presence in 360 videos. Implications for practice and/or policy Head‐mounted displays show promise as a delivery mode for 360 videos in teacher education. 360 videos should be personalized according to PST career and professional goals. The eXtended Reality Presence Scale is confirmed as a robust instrument to measure presence in immersive environments. More research is needed to evaluate the scalability of this approach in other contexts.

Novel Drug Delivery Systems for the Management of Fungal Keratitis.

Fungal keratitis (FK) is a dangerous corneal infection that is common in tropical and subtropical areas. Its incidence is extremely high, and ocular trauma and contact lenses can lead to FK, but its common treatment such as using topical antifungal eye drop instillation is often less effective because of several drawbacks of the drugs typically used, including limited ocular penetration, high frequency of dosing, poor biocompatibility, and the potential for severe drug reactions. Therefore, the development of novel drug delivery devices for the treatment of FK is urgent. The urgent need for novel drug delivery devices to treat FK has led to the development of several techniques, including nanoparticles (NPs), in situ forming hydrogels, contact lenses, and microneedles (MNs). However, it is important to note that the main mechanisms differ between these techniques. NPs can transport large amounts of drugs and be taken up by cells owing to their large surface area and small size. In situ forming hydrogels can significantly extend the residence time of drugs because of their strong adhesive properties. Contact lenses, with their comfortable shape and drug-carrying capacity, can also act as drug delivery devices. MNs can create channels in the cornea, bypassing its barrier and enhancing drug bioavailability. This article will go over novel medication delivery techniques for treating FK and make a conclusion about their advantages and limitations in anticipation to serve the best option for the individual therapy of FK.

A Comprehensive Review on Floating Drug Delivery System

The category of gastroretentive drug delivery systems (GRDDS) includes floating drug delivery systems (FDDS). These dose formulations are intended to extend the duration of the stomach's residence period by a sustained release technique. Drugs which are harder to dissolve in high pH environments have improved bioavailability and solubility when incorporated into GRDDS. Reduced intestinal absorption of solid dose forms can be accomplished by the flotation mechanism. The novel fusion of bilayer and floating mechanism is demonstrated by the bilayer floating drug delivery device. It demonstrates the effective creation of a controlled release formulation. Bilayer floating tablets offer a sustained release layer formulation in addition to an immediate release. A attempt was made to explain the mechanism of FDDS, or floating bilayer, in the review. In order to accomplish regulated administration of various medications with predetermined release profiles, bi-layer tablets were developed. The pharmaceutical industry has been more interested in creating bilayer tablets over the past ten years as a way to improve patient compliance and convenience by combining two or more API in a single dose form.

Monolithic silicon for high spatiotemporal translational photostimulation.

Electrode-based electrical stimulation underpins several clinical bioelectronic devices, including deep-brain stimulators1,2 and cardiac pacemakers3. However, leadless multisite stimulation is constrained by the technical difficulties and spatial-access limitations of electrode arrays. Optogenetics offers optically controlled random access with high spatiotemporal capabilities, but clinical translation poses challenges4-6. Here we show tunable spatiotemporal photostimulation of cardiac systems using a non-genetic platform based on semiconductor-enabled biomodulation interfaces. Through spatiotemporal profiling of photoelectrochemical currents, we assess the magnitude, precision, accuracy and resolution of photostimulation in four leadless silicon-based monolithic photoelectrochemical devices. We demonstrate the optoelectronic capabilities of the devices through optical overdrive pacing of cultured cardiomyocytes (CMs) targeting several regions and spatial extents, isolated rat hearts in a Langendorff apparatus, in vivo rat hearts in an ischaemia model and an in vivo mouse heart model with transthoracic optical pacing. We also perform the first, to our knowledge, optical override pacing and multisite pacing of a pig heart in vivo. Our systems are readily adaptable for minimally invasive clinical procedures using our custom endoscopic delivery device, with which we demonstrate closed-thoracic operations and endoscopic optical stimulation. Our results indicate the clinical potential of the leadless, lightweight and multisite photostimulation platform as a pacemaker in cardiac resynchronization therapy (CRT), in which lead-placement complications are common.

Sulfur Switches for Responsive Peptide Materials.

There is considerable recent interest in the synthesis and development of peptide-based materials as mimics of natural biological assemblies that utilize proteins and peptides to form organized structures and develop beneficial properties. Due to their potential compatibility with living organisms, synthetic peptide materials are also being developed for applications such as cell grafting, therapeutic delivery, and implantable diagnostic devices. One desirable feature for such applications is the ability to design materials that can respond to stimuli by changes in their structure or properties under biologically relevant conditions. Peptide and protein assemblies can respond to stimuli, such as changes in temperature, solution pH, ions present in media, or interactions with other biomacromolecules. An exciting area of emerging research is focused on how biology uses the chemistry of sulfur-containing amino acids as a means to regulate biological processes. These concepts have been utilized and expanded in recent years to enable the development of peptide materials with readily switchable properties.The incorporation of sulfur atoms in polypeptides, peptides, and proteins provides unique sites that can be used to alter the physical and biological properties of these materials. Sulfur-containing amino acid residues, most often cysteine and methionine, are able to undergo a variety of selective chemical and enzyme-mediated reactions, which can be broadly characterized as redox or alkylation processes. These reactions often proceed under physiologically relevant conditions, can be reversible, and are significant in that they can alter residue polarity as well as conformations of peptide chains. These sulfur-based reactions are able to switch molecular and macromolecular properties of peptides and proteins in living systems and recently have been applied to synthetic peptide materials. Naturally occurring "sulfur switches" can be reversible or irreversible and are often triggered by enzymatic activity. Sulfur switches in peptide materials can also be triggered in vitro using oxidation/reduction and alkylation as well as photochemical reactions. The application of sulfur switches to peptide materials has greatly expanded the scope of these switches due to the ability to readily incorporate a wide variety of noncanonical sulfur-containing synthetic amino acids.Sulfur switches have been shown to provide considerable potential to reversibly alter peptide material properties under mild physiologically relevant conditions. An important molecular feature of sulfur-containing amino acid residues was found to be the location of sulfur atoms in the side chains. The variation of sulfur atom positions from the backbone by single bond lengths was found to significantly affect polypeptide chain conformations upon oxidation-reduction or alkylation/dealkylation reactions. With the successful adaptation of sulfur switches to peptide materials, future studies can explore how these switches affect how these materials interact with biological systems. This Account provides an overview of the different types of sulfur switch reactions found in biology and their properties and the elaboration of these switches in synthetic systems with a focus on recent developments and applications of reversible sulfur switches in peptide materials.

A Miniaturized Device for Ultrafast On‐Demand Drug Release Based on a Gigahertz Ultrasonic Resonator

On‐demand controlled drug delivery is essential for the treatment of a wide range of chronic diseases. As the drug is released at the time when required, its efficacy is boosted and the side effects are minimized. However, so far, drug delivery devices often rely on the passive diffusion process for a sustained release, which is slow and uncontrollable. Herein, a miniaturized microfluidic device for wirelessly controlled ultrafast active drug delivery is presented, driven by an oscillating solid–liquid interface. The oscillation generates acoustic streaming in the drug reservoir, which opens an elastic valve to deliver the drug. High‐speed microscopy reveals the fast response of the valve on the order of 1 ms, which is more than three orders of magnitude faster than the start‐of‐the‐art. The amount of the released drug exhibits a linear relationship with the working time and the electric power applied to the ultrasonic resonator. The trigger of the release is wirelessly controlled via a magnetic field, and the system shows stable output in a continuous experiment for two weeks. The integrated system shows great promise as a long‐term controlled drug delivery implant for chronic diseases.