Mechanics of a mosquito bite with applications to microneedle design

Bending-activated biotensegrity structure enables female Megarhyssa to cross the barrier of Euler's critical force

The parasitic female Megarhyssa has a hair-like ovipositor capable of withstanding a penetration force 10 times greater than Euler's critical force, using a reciprocating penetration method. Understanding and replicating this penetration mechanism may notably broaden the application scenarios of artificial slender elements. Here, we show that the Megarhyssa's stretched intersegmental membrane and precurved abdomen activate the multipart ovipositor as a biotensegrity structure. The ovipositor's first and second valvulae alternately retract and protract, with each retracted valvula forming a tension network to support the other under compression, resulting in an exponentially increased critical force. We validated this mechanism in a multipart flexible microneedle that withstood a penetration force of 2.5× Euler's critical force and in a lightweight industrial robot that achieved intrinsic safety through its ideal dual-stiffness characteristic. This finding could potentially elucidate the high efficiency of insect probes and inspire more efficient and safer engineering designs.

Industrial perspectives for personalized microneedles

Microneedles and, subsequently, microneedle arrays are emerging miniaturized medical devices for painless transdermal drug delivery. New and improved additive manufacturing methods enable novel microneedle designs to be realized for preclinical and clinical trial assessments. However, current literature reviews suggest that industrial manufacturers and researchers have focused their efforts on one-size-fits-all designs for transdermal drug delivery, regardless of patient demographic and injection site. In this perspective article, we briefly review current microneedle designs, microfabrication methods, and industrialization strategies. We also provide an outlook where microneedles may become personalized according to a patient's demographic in order to increase drug delivery efficiency and reduce healing times for patient-centric care.

Honeybee stinger-based biopsy needle and influence of the barbs on needle forces during insertion/extraction into the iliac crest: A multilayer finite element approach

Bone marrow biopsy (BMB) needles are frequently used in medical procedures, including extracting biological tissue to identify specific lesions or abnormalities discovered during a medical examination or a radiological scan. The forces applied by the needle during the cutting operation significantly impact the sample quality. Excessive needle insertion force and possible deflection might cause tissue damage, compromising the integrity of the biopsy specimen. The present study aims at proposing a revolutionary bioinspired needle design that will be utilized during the BMB procedure. A non-linear finite element method (FEM) has been used to analyze the insertion/extraction mechanisms of the honeybee-inspired biopsy needle with barbs into/from the human skin-bone domain (i.e., iliac crest model). It can be seen from the results of the FEM analysis that stresses are concentrated around the bioinspired biopsy needle tip and barbs during the needle insertion process. Also, these needles reduce the insertion force and reduce the tip deflection. The insertion force in the current study has been reduced by 8.6% for bone tissue and 22.66% for skin tissue layers. Similarly, the extraction force has been reduced by an average of 57.54%. Additionally, it has been observed that the needle-tip deflection got reduced from 10.44 mm for a plain bevel needle to 6.3 mm for a barbed biopsy bevel needle. According to the research findings, the proposed bioinspired barbed biopsy needle design could be utilized to create and produce novel biopsy needles for successful and minimally invasive piercing operations.

A mosquito mouthpart-like bionic neural probe

Advancements in microscale electrode technology have revolutionized the field of neuroscience and clinical applications by offering high temporal and spatial resolution of recording and stimulation. Flexible neural probes, with their mechanical compliance to brain tissue, have been shown to be superior to rigid devices in terms of stability and longevity in chronic recordings. Shuttle devices are commonly used to assist flexible probe implantation; however, the protective membrane of the brain still makes penetration difficult. Hidden damage to brain vessels during implantation is a significant risk. Inspired by the anatomy of the mosquito mouthparts, we present a biomimetic neuroprobe system that integrates high-sensitivity sensors with a high-fidelity multichannel flexible electrode array. This customizable system achieves distributed and minimally invasive implantation across brain regions. Most importantly, the system's nonvisual monitoring capability provides an early warning detection for intracranial soft tissues, such as vessels, reducing the potential for injury during implantation. The neural probe system demonstrates exceptional sensitivity and adaptability to environmental stimuli, as well as outstanding performance in postoperative and chronic recordings. These findings suggest that our biomimetic neural-probe device offers promising potential for future applications in neuroscience and brain-machine interfaces. A mosquito mouthpart-like bionic neural probe consisting of a highly sensitive tactile sensor module, a flexible microelectrode array, and implanted modules that mimic the structure of mosquito mouthparts. The system enables distributed implantation of electrode arrays across multiple brain regions while making the implantation minimally invasive and avoiding additional dural removal. The tactile sensor array can monitor the implantation process to achieve early warning of vascular damage. The excellent postoperative short-term recording performance and long-term neural activity tracking ability demonstrate that the system is a promising tool in the field of brain-computer interfaces.

Mosquito Blood Feeding Prevention Using an Extra-Low DC Voltage Charged Cloth

Mosquito vector-borne diseases such as malaria and dengue pose a major threat to human health. Personal protection from mosquito blood feeding is mostly by treating clothing with insecticides and the use of repellents on clothing and skin. Here, we developed a low-voltage, mosquito-resistant cloth (MRC) that blocked all blood feeding across the textile and was flexible and breathable. The design was based on mosquito head and proboscis morphometrics, the development of a novel 3-D textile with the outer conductive layers insulated from each other with an inner, non-conductive woven mesh, and the use of a DC (direct current; extra-low-voltage) resistor-capacitor. Blockage of blood feeding was measured using host-seeking Aedes aegypti adult female mosquitoes and whether they could blood feed across the MRC and an artificial membrane. Mosquito blood feeding decreased as voltage increased from 0 to 15 volts. Blood feeding inhibition was 97.8% at 10 volts and 100% inhibition at 15 volts, demonstrating proof of concept. Current flow is minimal since conductance only occurs when the mosquito proboscis simultaneously touches the outside layers of the MRC and is then quickly repelled. Our results demonstrated for the first time the use of a biomimetic, mosquito-repelling technology to prevent blood feeding using extra-low energy consumption.

Recent advances in biomimetic hemostatic materials

Although the past decade has witnessed unprecedented medical advances, achieving rapid and effective hemostasis remains challenging. Uncontrolled bleeding and wound infections continue to plague healthcare providers, increasing the risk of death. Various types of hemostatic materials are nowadays used during clinical practice but have many limitations, including poor biocompatibility, toxicity and biodegradability. Recently, there has been a burgeoning interest in organisms that stick to objects or produce sticky substances. Indeed, applying biological adhesion properties to hemostatic materials remains an interesting approach. This paper reviews the biological behavior, bionics, and mechanisms related to hemostasis. Furthermore, this paper covers the benefits, challenges and prospects of biomimetic hemostatic materials.

Innovative Fabrication of Hollow Microneedle Arrays Enabling Blood Sampling with a Self-Powered Microfluidic Patch

Microneedles are gaining a lot of attention in the context of sampling cutaneous biofluids such as capillary blood. Their minimal invasiveness and user-friendliness make them a prominent substitute for venous puncture or finger-pricking. Although the latter is suitable for self-sampling, the impracticality of manual handling and the difficulty of obtaining enough qualitative sample is driving the search for better solutions. In this context, hollow microneedle arrays (HMNAs) are particularly interesting for completely integrating sample-to-answer solutions as they create a duct between the skin and the sampling device. However, the fabrication of sharp-tipped HMNAs with a high aspect ratio (AR) is challenging, especially since a length of ≥1500 μm is desired to reach the blood capillaries. In this paper, we first described a novel two-step fabrication protocol for HMNAs in stainless steel by percussion laser drilling and subsequent micro-milling. The HMNAs were then integrated into a self-powered microfluidic sampling patch, containing a capillary pump which was optimized to generate negative pressure differences up to 40.9 ± 1.8 kPa. The sampling patch was validated in vitro, showing the feasibility of sampling 40 μL of liquid. It is anticipated that our proof-of-concept is a starting point for more sophisticated all-in-one biofluid sampling and point-of-care testing systems.

Minimally invasive capillary blood sampling methods

INTRODUCTION

Whole blood samples, including arterial, venous, and capillary blood, are regularly used for disease diagnosis and monitoring. The global Covid-19 pandemic has highlighted the need for a more resilient screening capacity. Minimally invasive sampling techniques, such as capillary blood sampling, are routinely used for point of care testing in the home healthcare setting and clinical settings such as the Intensive Care Unit with less pain and wounding than conventional venepuncture.

AREAS COVERED

In this manuscript, we aim to provide a overview of state-of-the-art of techniques for obtaining samples of capillary blood. We first review both established and novel methods for releasing blood from capillaries in the skin. Next, we provide a comparison of different capillary blood sampling methods based on their mechanism, testing site, puncture size, cost, wound geometry, healing, and perceptions of pain. Finally, we overview established and new methods for enhancing capillary blood collection.

EXPERT OPINION

We expect that microneedles will prove to be a preferred option for paediatric blood collection. The ability of microneedles to collect a capillary blood sample without pain will improve paediatric healthcare outcomes. Jet injection may prove to be a useful method for facilitating both blood collection and drug delivery.

Experimental study of mosquito-inspired needle to minimize insertion force and tissue deformation

The aim of this work is to propose a mosquito-inspired (bioinspired) design of a surgical needle that can decrease the insertion force and the tissue deformation, which are the main causes of target inaccuracy during percutaneous procedures. The bioinspired needle was developed by mimicking the geometrical shapes of mosquito proboscis. Needle prototypes were manufactured and tested to determine optimized needle shapes and geometries. Needle insertion tests on a tissue-mimicking polyvinylchloride (PVC) gel were then performed to emulate the mosquito-proboscis stinging dynamics by applying vibration and insertion velocity during the insertion. An insertion test setup equipped with a sensing system was constructed to measure the insertion force and to assess the deformation of the tissue. It was discovered that using the proposed bioinspired design, the needle insertion force was decreased by 60% and the tissue deformation was reduced by 48%. This finding is significant for improving needle-based medical procedures.

Canvassing Prospects of Glyco-Nanovaccines for Developing Cross-Presentation Mediated Anti-Tumor Immunotherapy

In view of the severe downsides of conventional cancer therapies, the quest of developing alternative strategies still remains of critical importance. In this regard, antigen cross-presentation, usually employed by dendritic cells (DCs), has been recognized as a potential solution to overcome the present impasse in anti-cancer therapeutic strategies. It has been established that an elevated cytotoxic T lymphocyte (CTL) response against cancer cells can be achieved by targeting receptors expressed on DCs with specific ligands. Glycans are known to serve as ligands for C-type lectin receptors (CLRs) expressed on DCs, and are also known to act as a tumor-associated antigen (TAA), and, thus, can be harnessed as a potential immunotherapeutic target. In this scenario, integrating the knowledge of cross-presentation and glycan-conjugated nanovaccines can help us to develop so called 'glyco-nanovaccines' (GNVs) for targeting DCs. Here, we briefly review and analyze the potential of GNVs as the next-generation anti-tumor immunotherapy. We have compared different antigen-presenting cells (APCs) for their ability to cross-present antigens and described the potential nanocarriers for tumor antigen cross-presentation. Further, we discuss the role of glycans in targeting of DCs, the immune response due to pathogens, and imitative approaches, along with parameters, strategies, and challenges involved in cross-presentation-based GNVs for cancer immunotherapy. It is known that the effectiveness of GNVs in eradicating tumors by inducing strong CTL response in the tumor microenvironment (TME) has been largely hindered by tumor glycosylation and the expression of different lectin receptors (such as galectins) by cancer cells. Tumor glycan signatures can be sensed by a variety of lectins expressed on immune cells and mediate the immune suppression which, in turn, facilitates immune evasion. Therefore, a sound understanding of the glycan language of cancer cells, and glycan-lectin interaction between the cancer cells and immune cells, would help in strategically designing the next-generation GNVs for anti-tumor immunotherapy.

Biting Innovations of Mosquito-Based Biomaterials and Medical Devices

Mosquitoes are commonly viewed as pests and deadly predators by humans. Despite this perception, investigations of their survival-based behaviors, select anatomical features, and biological composition have led to the creation of several beneficial technologies for medical applications. In this review, we briefly explore these mosquito-based innovations by discussing how unique characteristics and behaviors of mosquitoes drive the development of select biomaterials and medical devices. Mosquito-inspired microneedles have been fabricated from a variety of materials, including biocompatible metals and polymers, to mimic of the mouthparts that some mosquitoes use to bite a host with minimal injury during blood collection. The salivary components that these mosquitoes use to reduce the clotting of blood extracted during the biting process provide a rich source of anticoagulants that could potentially be integrated into blood-contacting biomaterials or administered in therapeutics to reduce the risk of thrombosis. Mosquito movement, vision, and olfaction are other behaviors that also have the potential for inspiring the development of medically relevant technologies. For instance, viscoelastic proteins that facilitate mosquito movement are being investigated for use in tissue engineering and drug delivery applications. Even the non-wetting nanostructure of a mosquito eye has inspired the creation of a robust superhydrophobic surface coating that shows promise for biomaterial and drug delivery applications. Additionally, biosensors incorporating mosquito olfactory receptors have been built to detect disease-specific volatile organic compounds. Advanced technologies derived from mosquitoes, and insects in general, form a research area that is ripe for exploration and can uncover potential in further dissecting mosquito features for the continued development of novel medical innovations.

Application of microneedle patches for drug delivery; doorstep to novel therapies

In the past decade, microneedle-based drug delivery systems showed promising approaches to become suitable and alternative for hypodermic injections and can control agent delivery without side effects compared to conventional approaches. Despite these advantages, the procedure of microfabrication is facing some difficulties. For instance, drug loading method, stability of drugs, and retention time are subjects of debate. Besides, the application of novel refining fabrication methods, types of materials, and instruments are other issues that need further attention. Herein, we tried to summarize recent achievements in controllable drug delivery systems (microneedle patches) in vitro and in vivo settings. In addition, we discussed the influence of delivered drugs on the cellular mechanism and immunization molecular signaling pathways through the intradermal delivery route. Understanding the putative efficiency of microneedle patches in human medicine can help us develop and design sophisticated therapeutic modalities.

Dengue virus infection modifies mosquito blood-feeding behavior to increase transmission to the host

Because dengue viruses are spread by mosquitoes during biting, transmission capacity depends on mosquito-biting behavior. For this reason, it is critical to understand how infection in mosquitoes influences biting. To answer this question, we deployed a multidisciplinary approach including high-resolution, multivariate biting behavior monitoring on mice, in vivo transmission assay, and mathematical modeling. We demonstrated that infected mosquitoes are more attracted to mice and bite more often to get the same amount of blood as uninfected mosquitoes. While the effect of increased attraction to host on transmission capacity is trivial, we showed that increased number of bites results in successive transmission. Eventually, we calculated that the infection-induced behavior changes tripled transmission capacity of mosquitoes.

Mosquito blood-feeding behavior is a key determinant of the epidemiology of dengue viruses (DENV), the most-prevalent mosquito-borne viruses. However, despite its importance, how DENV infection influences mosquito blood-feeding and, consequently, transmission remains unclear. Here, we developed a high-resolution, video-based assay to observe the blood-feeding behavior of Aedes aegypti mosquitoes on mice. We then applied multivariate analysis on the high-throughput, unbiased data generated from the assay to ordinate behavioral parameters into complex behaviors. We showed that DENV infection increases mosquito attraction to the host and hinders its biting efficiency, the latter resulting in the infected mosquitoes biting more to reach similar blood repletion as uninfected mosquitoes. To examine how increased biting influences DENV transmission to the host, we established an in vivo transmission model with immuno-competent mice and demonstrated that successive short probes result in multiple transmissions. Finally, to determine how DENV-induced alterations of host-seeking and biting behaviors influence dengue epidemiology, we integrated the behavioral data within a mathematical model. We calculated that the number of infected hosts per infected mosquito, as determined by the reproduction rate, tripled when mosquito behavior was influenced by DENV infection. Taken together, this multidisciplinary study details how DENV infection modulates mosquito blood-feeding behavior to increase vector capacity, proportionally aggravating DENV epidemiology. By elucidating the contribution of mosquito behavioral alterations on DENV transmission to the host, these results will inform epidemiological modeling to tailor improved interventions against dengue.

A microfluidic platform for highly parallel bite by bite profiling of mosquito-borne pathogen transmission

Mosquito bites transmit a number of pathogens via salivary droplets deposited during blood-feeding, resulting in potentially fatal diseases. Little is known about the genomic content of these nanodroplets, including the transmission dynamics of live pathogens. Here we introduce Vectorchip, a low-cost, scalable microfluidic platform enabling high-throughput molecular interrogation of individual mosquito bites. We introduce an ultra-thin PDMS membrane which acts as a biting interface to arrays of micro-wells. Freely-behaving mosquitoes deposit saliva droplets by biting into these micro-wells. By modulating membrane thickness, we observe species-dependent differences in mosquito biting capacity, utilizable for selective sample collection. We demonstrate RT-PCR and focus-forming assays on-chip to detect mosquito DNA, Zika virus RNA, as well as quantify infectious Mayaro virus particles transmitted from single mosquito bites. The Vectorchip presents a promising approach for single-bite-resolution laboratory and field characterization of vector-pathogen communities, and could serve as a powerful early warning sentinel for mosquito-borne diseases.

Plasmodium metabolite HMBPP stimulates feeding of main mosquito vectors on blood and artificial toxic sources

Recent data show that parasites manipulate the physiology of mosquitoes and human hosts to increase the probability of transmission. Here, we investigate phagostimulant activity of Plasmodium-metabolite, (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP), in the primary vectors of multiple human diseases, Anopheles coluzzii, An. arabiensis, An. gambiae s.s., Aedes aegypti, and Culex pipiens/Culex torrentium complex species. The addition of 10 µM HMBPP to blood meals significantly increased feeding in all the species investigated. Moreover, HMBPP also exhibited a phagostimulant property in plant-based-artificial-feeding-solution made of beetroot juice adjusted to neutral pH similar to that of blood. The addition of AlbuMAXTM as a lipid/protein source significantly improved the feeding rate of An. gambiae s.l. females providing optimised plant-based-artificial-feeding-solution for delivery toxins to control vector populations. Among natural and synthetic toxins tested, only fipronil sulfone did not reduce feeding. Overall, the toxic-plant-based-artificial-feeding-solution showed potential as an effector in environmentally friendly vector-control strategies.

Did giraffe cardiovascular evolution solve the problem of heart failure with preserved ejection fraction?

The evolved adaptations of other species can be a source of insight for novel biomedical innovation. Limitations of traditional animal models for the study of some pathologies are fueling efforts to find new approaches to biomedical investigation. One emerging approach recognizes the evolved adaptations in other species as possible solutions to human pathology. The giraffe heart, for example, appears resistant to pathology related to heart failure with preserved ejection fraction (HFpEF)—a leading form of hypertension-associated cardiovascular disease in humans. Here, we postulate that the physiological pressure-induced left ventricular thickening in giraffes does not result in the pathological cardiovascular changes observed in humans with hypertension. The mechanisms underlying this cardiovascular adaptation to high blood pressure in the giraffe may be a bioinspired roadmap for preventive and therapeutic strategies for human HFpEF.

Mosquito-Textile Physics: A Mathematical Roadmap to Insecticide-Free, Bite-Proof Clothing for Everyday Life

Simple Summary

Mosquitoes can bite across clothing and transmit disease. This is prevented with pesticides applied to clothing. We developed non-insecticidal cloth and garments that provided 100% protection, were comfortable and look-like and feel-like regular clothing.

Abstract

Garments treated with chemical insecticides are commonly used to prevent mosquito bites. Resistance to insecticides, however, is threatening the efficacy of this technology, and people are increasingly concerned about the potential health impacts of wearing insecticide-treated clothing. Here, we report a mathematical model for fabric barriers that resist bites from Aedes aegypti mosquitoes based on textile physical structure and no insecticides. The model was derived from mosquito morphometrics and analysis of mosquito biting behavior. Woven filter fabrics, precision polypropylene plates, and knitted fabrics were used for model validation. Then, based on the model predictions, prototype knitted textiles and garments were developed that prevented mosquito biting, and comfort testing showed the garments to possess superior thermophysiological properties. Our fabrics provided a three-times greater bite resistance than the insecticide-treated cloth. Our predictive model can be used to develop additional textiles in the future for garments that are highly bite resistant to mosquitoes.

Deep indentation and puncture of a rigid cylinder inserted into a soft solid

Deep indentation and puncture can be used to characterize the large strain elastic and fracture properties of soft solids and biological tissues. While this characterization method is growing in application there are still open questions about deep indentation and puncture, including how the distribution of strains and stresses in the surrounding material relate to the resultant force exerted on the indenter. Direct quantification of the deformation field around a rigid indenter during penetration of a soft solid is necessary to substantiate the current qualitative understanding of these strains and increase the impact and usefulness of puncture tests. Here, the deformation field of a rigid cylinder inserted into a soft solid is quantified using digital image correlation (DIC). DIC measurements are validated by reconstituting the measured nominal force on the cylinder during deep indentation and puncture. The deformation field is used to map the strain field around the indenter during deep indentation and puncture. These measurements provide direct insight into the puncture process and show that while the resultant force mainly arises from the sheared region on the sides of the indenter, the compressed region below the tip is responsible for initiating failure.

Quantifying and Modeling the Acquisition and Retention of Lumpy Skin Disease Virus by Hematophagus Insects Reveals Clinically but Not Subclinically Affected Cattle Are Promoters of Viral Transmission and Key Targets for Control of Disease Outbreaks

Lumpy skin disease virus (LSDV) causes a severe systemic disease characterized by cutaneous nodules in cattle. LSDV is a rapidly emerging pathogen, having spread since 2012 into Europe and Russia and across Asia.

Lumpy skin disease virus (LSDV) is a vector-transmitted poxvirus that causes disease in cattle. Vector species involved in LSDV transmission and their ability to acquire and transmit the virus are poorly characterized. Using a highly representative bovine experimental model of lumpy skin disease, we fed four model vector species (Aedes aegypti, Culex quinquefasciatus, Stomoxys calcitrans, and Culicoides nubeculosus) on LSDV-inoculated cattle in order to examine their acquisition and retention of LSDV. Subclinical disease was a more common outcome than clinical disease in the inoculated cattle. Importantly, the probability of vectors acquiring LSDV from a subclinical animal (0.006) was very low compared with that from a clinical animal (0.23), meaning an insect feeding on a subclinical animal was 97% less likely to acquire LSDV than one feeding on a clinical animal. All four potential vector species studied acquired LSDV from the host at a similar rate, but Aedes aegypti and Stomoxys calcitrans retained the virus for a longer time, up to 8 days. There was no evidence of virus replication in the vector, consistent with mechanical rather than biological transmission. The parameters obtained in this study were combined with data from studies of LSDV transmission and vector life history parameters to determine the basic reproduction number of LSDV in cattle mediated by each of the model species. This reproduction number was highest for Stomoxys calcitrans (19.1), followed by C. nubeculosus (7.1) and Ae. aegypti (2.4), indicating that these three species are potentially efficient transmitters of LSDV; this information can be used to inform LSD control programs.

IMPORTANCE Lumpy skin disease virus (LSDV) causes a severe systemic disease characterized by cutaneous nodules in cattle. LSDV is a rapidly emerging pathogen, having spread since 2012 into Europe and Russia and across Asia. The vector-borne nature of LSDV transmission is believed to have promoted this rapid geographic spread of the virus; however, a lack of quantitative evidence about LSDV transmission has hampered effective control of the disease during the current epidemic. Our research shows subclinical cattle play little part in virus transmission relative to clinical cattle and reveals a low probability of virus acquisition by insects at the preclinical stage. We have also calculated the reproductive number of different insect species, therefore identifying efficient transmitters of LSDV. This information is of utmost importance, as it will help to define epidemiological control measures during LSDV epidemics and of particular consequence in resource-poor regions where LSD vaccination may be less than adequate.

Clustering and Erratic Movement Patterns of Syringe-Injected versus Mosquito-Inoculated Malaria Sporozoites Underlie Decreased Infectivity

Malaria vaccine candidates based on live, attenuated sporozoites have led to high levels of protection. However, their efficacy critically depends on the sporozoites' ability to reach and infect the host liver. Administration via mosquito inoculation is by far the most potent method for inducing immunity but highly impractical. Here, we observed that intradermal syringe-injected Plasmodium berghei sporozoites (^syrSPZ) were 3-fold less efficient in migrating to and infecting mouse liver than mosquito-inoculated sporozoites (^msqSPZ). This was related to a clustered dermal distribution (2-fold-decreased median distance between ^syrSPZ and ^msqSPZ) and, more importantly, a 1.4-fold (significantly)-slower and more erratic movement pattern. These erratic movement patterns were likely caused by alteration of dermal tissue morphology (>15-μm intercellular gaps) due to injection of fluid and may critically decrease sporozoite infectivity. These results suggest that novel microvolume-based administration technologies hold promise for replicating the success of mosquito-inoculated live, attenuated sporozoite vaccines.IMPORTANCE Malaria still causes a major burden on global health and the economy. The efficacy of live, attenuated malaria sporozoites as vaccine candidates critically depends on their ability to migrate to and infect the host liver. This work sheds light on the effect of different administration routes on sporozoite migration. We show that the delivery of sporozoites via mosquito inoculation is more efficient than syringe injection; however, this route of administration is highly impractical for vaccine purposes. Using confocal microscopy and automated imaging software, we demonstrate that syringe-injected sporozoites do cluster, move more slowly, and display more erratic movement due to alterations in tissue morphology. These findings indicate that microneedle-based engineering solutions hold promise for replicating the success of mosquito-inoculated live, attenuated sporozoite vaccines.

Sensory Discrimination of Blood and Floral Nectar by Aedes aegypti Mosquitoes

Blood-feeding mosquitoes survive by feeding on nectar for metabolic energy but require a blood meal to develop eggs. Aedes aegypti females must accurately discriminate blood and nectar because each meal promotes mutually exclusive feeding programs with distinct sensory appendages, meal sizes, digestive tract targets, and metabolic fates. We investigated the syringe-like blood-feeding appendage, the stylet, and discovered that sexually dimorphic stylet neurons taste blood. Using pan-neuronal calcium imaging, we found that blood is detected by four functionally distinct stylet neuron classes, each tuned to specific blood components associated with diverse taste qualities. Stylet neurons are insensitive to nectar-specific sugars and respond to glucose only in the presence of additional blood components. The distinction between blood and nectar is therefore encoded in specialized neurons at the very first level of sensory detection in mosquitoes. This innate ability to recognize blood is the basis of vector-borne disease transmission to millions of people worldwide.

Making the cut: mechanics of cutting and steering of insect probes

Many insects forage, oviposit or inject venom in their prey by penetrating or cutting through substrates. From a physical perspective, cutting involves creation of new free surfaces. The cutting parts of insects, such as their mandibles or ovipositor tips, are often zinc-enriched and hardened as compared to the other cuticular regions. Whereas tip hardening is key to their ability to penetrate surfaces, it is often also important for probes to be maneuverable through substrates. How do insect probes negotiate the trade-off between cutting and steering through substrates of diverse stiffness? To address this question, we review the morphology, mechanics, and adaptations in the cutting parts of various insects. Understanding these mechanisms will allow us to develop biomimetic tools, including agricultural and surgical tools, that can both cut and steer through diverse substrates.

Lancing Drug Reservoirs into Subcutaneous Fat to Combat Obesity and Associated Metabolic Diseases

Obesity is a serious epidemic health problem that can cause many other diseases including type 2 diabetes and cardiovascular diseases. Current approaches to combat obesity suffer from low effectiveness and adverse side effects. Here, a new self-administrable and minimally invasive transdermal drug delivery strategy for home-based long-term treatment of obesity and other diseases is developed. Specifically, ultrathin, core-shelled, and lance-shaped polymeric drug reservoirs (micro-lances [MLs]) are readily fabricated by a thermal pressing molding method and totally implanted into subcutaneous fat by lancing through the skin. Using a diet-induced obese mouse model, it is shown that the development of obesity and associated metabolic disorders is effectively inhibited by applying therapeutic core-shelled MLs once every 2 weeks. The outstanding therapeutic effects are attributable to highly localized and biphasic drug release, as well as combination therapy based on browning transformation of white fat and enhanced insulin sensitivity.

Mosquito proboscis-inspired needle insertion to reduce tissue deformation and organ displacement

This study investigates mosquito proboscis-inspired (MPI) insertion applied to the clinically used biopsy needle to reduce tissue deformation and organ displacement. Advanced medical imagining has enabled early-stage identification of cancerous lesions that require needle biopsy for minimally invasive tissue sampling and pathological analysis. Accurate cancer diagnosis depends on the accuracy of needle deployment to the targeted cancerous lesion site. However, currently available needle delivery systems deform and move soft tissue and organs, leading to a non-diagnostic biopsy or undersampling of the target. Two features inspired by the mosquito proboscis were adopted for MPI insertion in prostate biopsy: (1) the harpoon-shape notches at the needle tip and (2) reciprocating needle-cannula motions for incremental insertion. The local tissue deformation and global prostate displacement during the MPI vs. traditional direct insertions were quantified by optically tracking the displacement of particle-embedded tissue-mimicking phantoms. Results show that the MPI needle insertion reduced both local tissue deformation and global prostate displacement because of the opposite needle-cannula motions and notches which stabilized and reduced the tissue deformation during insertion. Findings provide proof of concept for MPI insertion in the clinical biopsy procedures as well as insights of needle–tissue interaction for future biopsy technology development.

Effect of vibration on insertion force and deflection of bioinspired needle in tissues

The design of surgical needles used in biopsy procedures have remained fairly standard despite the increase in complexity of surgeries. Higher needle insertion forces and deflection can increase tissue damage and decrease biopsy sample integrity. To overcome these drawbacks, we present a novel bioinspired approach to reduce insertion forces and minimize needle-tip deflection. It is well known from the literature, design of bioinspired surgical needles results in decreasing insertion forces and needle-tip deflection from the needle insertion path. This technical note studies the influence of vibration on bioinspired needle to further reduce insertion forces and needle-tip deflection. Bioinspired needle geometrical parameters such as barb shapes and geometries were analyzed to determine the best design parameters. Static and dynamic (vibration) needle insertion tests were performed to determine the maximum insertion forces and to estimate needle-tip deflection. Our results show that introducing vibration on the bioinspired needle insertion can reduce the maximum insertion force by up to 50%. It was also found that the needle-tip deflection is decreased by 47%.

Mosquito bite prevention through graphene barrier layers

Graphene-based materials are being developed for a variety of wearable technologies to provide advanced functions that include sensing; temperature regulation; chemical, mechanical, or radiative protection; or energy storage. We hypothesized that graphene films may also offer an additional unanticipated function: mosquito bite protection for light, fiber-based fabrics. Here, we investigate the fundamental interactions between graphene-based films and the globally important mosquito species, Aedes aegypti, through a combination of live mosquito experiments, needle penetration force measurements, and mathematical modeling of mechanical puncture phenomena. The results show that graphene or graphene oxide nanosheet films in the dry state are highly effective at suppressing mosquito biting behavior on live human skin. Surprisingly, behavioral assays indicate that the primary mechanism is not mechanical puncture resistance, but rather interference with host chemosensing. This interference is proposed to be a molecular barrier effect that prevents Aedes from detecting skin-associated molecular attractants trapped beneath the graphene films and thus prevents the initiation of biting behavior. The molecular barrier effect can be circumvented by placing water or human sweat as molecular attractants on the top (external) film surface. In this scenario, pristine graphene films continue to protect through puncture resistance-a mechanical barrier effect-while graphene oxide films absorb the water and convert to mechanically soft hydrogels that become nonprotective.

Bioinspired Adhesive Architectures: From Skin Patch to Integrated Bioelectronics

The attachment phenomena of various hierarchical architectures found in nature have extensively drawn attention for developing highly biocompatible adhesive on skin or wet inner organs without any chemical glue. Structural adhesive systems have become important to address the issues of human-machine interactions by smart outer/inner organ-attachable devices for diagnosis and therapy. Here, advances in designs of biologically inspired adhesive architectures are reviewed in terms of distinct structural properties, attachment mechanisms to biosurfaces by physical interactions, and noteworthy fabrication methods. Recent demonstrations of bioinspired adhesive architectures as adhesive layers for medical applications from skin patches to multifunctional bioelectronics are presented. To conclude, current challenges and prospects on potential applications are also briefly discussed.

Microneedle-based intradermal delivery of stabilized dengue virus

Current live-attenuated dengue vaccines require strict cold chain storage. Methods to preserve dengue virus (DENV) viability, which enable vaccines to be transported and administered at ambient temperatures, will be decisive towards the implementation of affordable global vaccination schemes with broad immunization coverage in resource-limited areas. We have developed a microneedle (MN)-based vaccine platform for the stabilization and intradermal delivery of live DENV from minimally invasive skin patches. Dengue virus-stabilized microneedle arrays (VSMN) were fabricated using saccharide-based formulation of virus and could be stored dry at ambient temperature up to 3 weeks with maintained virus viability. Following intradermal vaccination, VSMN-delivered DENV was shown to elicit strong neutralizing antibody responses and protection from viral challenge, comparable to that of the conventional liquid vaccine administered subcutaneously. This work supports the potential for MN-based dengue vaccine technology and the progression towards cold chain-independence. Dengue virus can be stabilized using saccharide-based formulations and coated on microneedle array vaccine patches for storage in dry state with preserved viability at ambient temperature (VSMN; virus-stabilized microneedle arrays).

Making a point: shared mechanics underlying the diversity of biological puncture

A viper injecting venom into a target, a mantis shrimp harpooning a fish, a cactus dispersing itself via spines attaching to passing mammals; all these are examples of biological puncture. Although disparate in terms of materials, kinematics and phylogeny, all three examples must adhere to the same set of fundamental physical laws that govern puncture mechanics. The diversity of biological puncture systems is a good case study for how physical laws can be used as a baseline for comparing disparate biological systems. In this Review, I explore the diversity of biological puncture and identify key variables that influence these systems. First, I explore recent work on biological puncture in a diversity of organisms, based on their hypothesized objectives: gripping, injection, damage and defence. Variation within each category is discussed, such as the differences between gripping for prey capture, gripping for dispersal of materials or gripping during reproduction. The second half of the Review is focused on specific physical parameters that influence puncture mechanics, such as material properties, stress, energy, speed and the medium within which puncture occurs. I focus on how these parameters have been examined in biology, and how they influence the evolution of biological systems. The ultimate objective of this Review is to outline an initial framework for examining the mechanics and evolution of puncture systems across biology. This framework will not only allow for broad biological comparisons, but also create a baseline for bioinspired design of both tools that puncture efficiently and materials that can resist puncture.

Functional principles of steerable multi-element probes in insects

Hemipterans, mosquitoes, and parasitic wasps probe in a variety of substrates to find hosts for their larvae or food sources. Probes capable of sensing and precise steering enable insects to navigate through solid substrates without visual information and to reach targets that are hidden deep inside the substrate. The probes belong to non‐related taxa and originate from abdominal structures (wasps) or mouthparts (hemipterans and mosquitoes), but nevertheless share several morphological characteristics. Although the transport function clearly differs (egg laying and acquisition of liquid food), the functional demands on the mechanical behaviour of the probe within the substrate tend to be similar. The probe needs to be thin to limit substrate deformation, and long, in order to attain substantial path lengths or depths. We linked the morphology across taxa to the different functional requirements, to provide insights into the biology of probing insects and the evolution of their probes.

Current knowledge of insect probes is spread over many taxa, which offers the possibility to derive general characteristics of insect probing. Buckling during initial puncturing is limited by external support mechanisms. The probe itself consist of multiple (3–6) parts capable of sliding along one another. This multi‐part construction presumably enables advancement and precise three‐dimensional steering of the probe through the substrate with very low net external pushing forces, preventing buckling during substrate penetration. From a mechanical viewpoint, a minimum of three elements is required for 3D steering and volumetric exploration, as realised in the ovipositors of wasps. More elements, such as in six‐element probes of mosquitoes, may enhance friction in soft substrates. Alternatively, additional elements can have functions other than ‘drilling’, such as saliva injection in mosquitoes.

Despite the gross similarities, probes show differences in their cross sections, tip morphologies, relative lengths of their elements, and the shape of their interconnections. The hypothesis is that the probe morphology is influenced by the substrate properties, which are mostly unknown. Correlating the observed diversity to substrate‐specific functional demands is therefore currently impossible.

We conclude that a multipart probe with sliding elements is highly effective for volumetric substrate probing. Shared functional demands have led to an evolutionary convergence of slender multi‐element probes in disparate insect taxa. To fully understand 3D probing, it is necessary to study the sensory and material properties, as well as the detailed kinematics and dynamics of the various probes in relation to the nature of the selective pressure originating from the species‐specific substrates. Such knowledge will deepen our understanding of probing mechanisms and may support the development of slender, bio‐inspired probes.

Additive Manufacturing of Honeybee-Inspired Microneedle for Easy Skin Insertion and Difficult Removal

With natural evolution, honeybee stinger with microbarbs can easily penetrate and trap in the skin of hostile animals to inject venom for self-defense. We proposed a novel three-dimensional additive manufacturing method, namely magnetorheological drawing lithography, to efficiently fabricate a bioinspired microneedle imitating a honeybee stinger. Under the assistance of an external magnetic field, a parent microneedle was directly drawn on the pillar tip, and tilted microbarbs were subsequently formed on the four sides of the parent microneedle. Compared with the barbless microneedle, the microstructured barbs enable the bioinspired microneedle for easy skin insertion and difficult removal. The extraction-penetration force ratio of the bioinspired microneedle was triple that of the barbless microneedle. The stress concentration at the barbs helps to reduce the insertion force of the bioinspired microneedle by minimizing the frictional force, whereas it increases the adhesion force by interlocking the barbs in the tissue during retraction. Such finds may provide an inspiration for further design of barbed microtip-based microneedles for tissue adhesion, transdermal drug delivery, biosignal recording, and so on.

On the Materials Science of Nature's Arms Race

Biological material systems have evolved unique combinations of mechanical properties to fulfill their specific function through a series of ingenious designs. Seeking lessons from Nature by replicating the underlying principles of such biological materials offers new promise for creating unique combinations of properties in man-made systems. One case in point is Nature's means of attack and defense. During the long-term evolutionary "arms race," naturally evolved weapons have achieved exceptional mechanical efficiency with a synergy of effective offense and persistence-two characteristics that often tend to be mutually exclusive in many synthetic systems-which may present a notable source of new materials science knowledge and inspiration. This review categorizes Nature's weapons into ten distinct groups, and discusses the unique structural and mechanical designs of each group by taking representative systems as examples. The approach described is to extract the common principles underlying such designs that could be translated into man-made materials. Further, recent advances in replicating the design principles of natural weapons at differing lengthscales in artificial materials, devices and tools to tackle practical problems are revisited, and the challenges associated with biological and bioinspired materials research in terms of both processing and properties are discussed.

Lessons from mosquitoes' painless piercing

Arthropods are the largest group of the living organisms. They attack other organisms by biting, stinging, or piercing and sucking. Among various medically important arthropods, which feed on living hosts, mosquitoes' piercing spread viruses which have been reported to cause the highest number of deaths annually. The primary cause of the deaths is malaria, which is spread by infected mosquitoes' piercing. This study aims at elucidating lessons from mosquitoes' painless piercing. Mosquitoes pierce using their fascicle, which is a bundle of coherently functioning six stylets. Based on experiments and available literature, it is presented that mosquitoes painlessly pierce using a combination of the numbing, the fascicle's serrated design, the vibratory actuation, and the graded and frequency-dependent mechanical properties of the labrum. Based on this understanding, a mosquito-inspired microneedle design has also been proposed.

A Mosquito Inspired Strategy to Implant Microprobes into the Brain

Mosquitos are among the deadliest insects on the planet due to their ability to transmit diseases like malaria through their bite. In order to bite, a mosquito must insert a set of micro-sized needles through the skin to reach vascular structures. The mosquito uses a combination of mechanisms including an insertion guide to enable it to bite and feed off of larger animals. Here, we report on a biomimetic strategy inspired by the mosquito insertion guide to enable the implantation of intracortical microelectrodes into the brain. Next generation microelectrode designs leveraging ultra-small dimensions and/or flexible materials offer the promise of increased performance, but present difficulties in reliable implantation. With the biomimetic guide in place, the rate of successful microprobe insertion increased from 37.5% to 100% due to the rise in the critical buckling force of the microprobes by 3.8-fold. The prototype guides presented here provide a reproducible method to augment the insertion of small, flexible devices into the brain. In the future, similar approaches may be considered and applied to the insertion of other difficult to implant medical devices.

Micro/nano-particle decorated metal wire for cutting soft matter

To cut soft materials such as biological tissues with minimal damage and reduced positional error is highly desired in medical surgery and biomechanics. After years of natural selection and evolution, mosquitoes have acquired the ability to insert their proboscises into human skin with astonishingly tiny forces. This can be associated with the unique structure of their proboscises, with micro/nano sawteeth, and the distinctive insertion manner: high frequency reciprocating saw cutting. Inspired by these, this communication describes the successful implantation of metal oxide particles onto molybdenum wire surfaces through a sol-calcination process, to form a biomimetic sawblade with a high density of micro/nano saw teeth, where the acidification is essential in terms of generating active anchoring sites on the wire. When used as a sawblade in conjunction with reciprocating action to cut the viscoelastic gel, both the cut-in force and cut-in displacement could be decreased substantially. The cutting speed and frequency of reciprocating action are important operating parameters influencing cut-in force.

Buckling prevention strategies in nature as inspiration for improving percutaneous instruments: a review

A typical mechanical failure mode observed in slender percutaneous instruments, such as needles and guidewires, is buckling. Buckling is observed when the axial compressive force that is required to penetrate certain tissue types exceeds the critical load of the instrument and manifests itself by sudden lateral deflection of the instrument. In nature, several organisms are able to penetrate substrates without buckling while using apparatuses with diameters smaller than those of off-the-shelf available percutaneous needles and guidewires. In this study we reviewed the apparatuses and buckling prevention strategies employed by biological organisms to penetrate substrates such as wood and skin. A subdivision is made between buckling prevention strategies that focus on increasing the critical load of the penetration tool and strategies that focus on decreasing the penetration load of the substrate. In total, 28 buckling prevention strategies were identified and categorized. Most organisms appear to be using a combination of buckling prevention strategies simultaneously. Integration and combination of these biological buckling prevention strategies in percutaneous instruments may contribute to increasing the success rate of percutaneous interventions.

Buckling failures in insect exoskeletons

Thin walled tubes are often used for load-bearing structures, in nature and in engineering, because they offer good resistance to bending and torsion at relatively low weight. However, when loaded in bending they are prone to failure by buckling. It is difficult to predict the loading conditions which cause buckling, especially for tubes whose cross sections are not simple shapes. Insights into buckling prevention might be gained by studying this phenomenon in the exoskeletons of insects and other arthropods. We investigated the leg segments (tibiae) of five different insects: the locust (Schistocerca gergaria), American cockroach (Periplaneta americana), death's head cockroach (Blaberus discoidalis), stick insect (Parapachymorpha zomproi) and bumblebee (Bombus terrestris audax). These were tested to failure in cantilever bending and modelled using finite element analysis (FEA). The tibiae of the locust and the cockroaches were found to be approximately circular in shape. Their buckling loads were well predicted by linear elastic FEA, and also by one of the analytical solutions available in the literature for elastic buckling. The legs of the stick insect are also circular in cross section but have several prominent longitudinal ridges. We hypothesised that these ridges might protect the legs against buckling but we found that this was not the case: the loads necessary for elastic buckling were not reached in practice because yield occurred in the material, causing plastic buckling. The legs of bees have a non-circular cross section due to a pollen-carrying feature (the corbicula). We found that this did not significantly affect their resistance to buckling. Our results imply that buckling is the dominant failure mode in the tibia of insects; it likely to be a significant consideration for other arthropods and any organisms with stiff exoskeletons. The interactions displayed here between material properties and cross sectional geometry may provide insights for the biomimetic design of engineering structures using thin walled tubes.

Comparison of the functional features of the pump organs of Anopheles sinensis and Aedes togoi

Mosquitoes act as vectors for severe tropical diseases. Mosquito-borne diseases are affected by various factors such as environmental conditions, host body susceptibility, and mosquito feeding behavior. Among these factors, feeding behavior is affected by the feeding pump system located inside the mosquito head and also depends on the species of mosquito. Therefore, the 3D morphological structures of the feeding pumps of Aedes togoi and Anopheles sinensis were comparatively investigated using synchrotron X-ray microscopic computed tomography. In addition, the feeding behaviors of their pumping organs were also investigated using a 2D X-ray micro-imaging technique. An. sinensis, a malarial vector mosquito, had a larger feeding pump volume than Ae. togoi in the static or resting position. Interestingly, the two species of mosquitoes exhibited different feeding behaviors. Ae. togoi had a higher feeding frequency and expansion ratio than An. sinensis. Ae. togoi also exhibited F-actin localization more clearly. These distinctive variations in feeding volumes and behaviors provide essential insight into the blood-feeding mechanisms of female mosquitoes as vectors for tropical diseases.

Early Events in Chikungunya Virus Infection-From Virus Cell Binding to Membrane Fusion

Chikungunya virus (CHIKV) is a rapidly emerging mosquito-borne alphavirus causing millions of infections in the tropical and subtropical regions of the world. CHIKV infection often leads to an acute self-limited febrile illness with debilitating myalgia and arthralgia. A potential long-term complication of CHIKV infection is severe joint pain, which can last for months to years. There are no vaccines or specific therapeutics available to prevent or treat infection. This review describes the critical steps in CHIKV cell entry. We summarize the latest studies on the virus-cell tropism, virus-receptor binding, internalization, membrane fusion and review the molecules and compounds that have been described to interfere with virus cell entry. The aim of the review is to give the reader a state-of-the-art overview on CHIKV cell entry and to provide an outlook on potential new avenues in CHIKV research.

Microneedle-mediated minimally invasive patient monitoring

BACKGROUND

The emerging field of microneedle-based minimally invasive patient monitoring and diagnosis is reviewed. Microneedle arrays consist of rows of micron-scale projections attached to a solid support. They have been widely investigated for transdermal drug and vaccine delivery applications since the late 1990s. However, researchers and clinicians have recently realized the great potential of microneedles for extraction of skin interstitial fluid and, less commonly, blood, for enhanced monitoring of patient health.

METHODS

We reviewed the journal and patent literature, and summarized the findings and provided technical insights and critical analysis.

RESULTS

We describe the basic concepts in detail and extensively review the work performed to date.

CONCLUSIONS

It is our view that microneedles will have an important role to play in clinical management of patients and will ultimately improve therapeutic outcomes for people worldwide.