Microneedle technology for potential SARS-CoV-2 vaccine delivery.

INTRODUCTION: Microneedle fabrication was conceptualized in the 1970s as devices for painless transdermal drug delivery. The last two decades have seen considerable research and financial investment in this area with SARS-CoV-2 and other vaccines catalyzing their application to in vivo intradermal vaccine delivery. Microneedle arrays have been fabricated in different shapes, geometries, formats, and out of different materials. AREAS COVERED: The recent pandemic has offered microneedle platforms the opportunity to be employed as a vehicle for SARS-CoV-2 vaccine administration. Various modes of vaccination delivery and the potential of microneedle array-based vaccines will be presented, with a specific focus placed on recent SARS-CoV-2 research. The advantages of microneedle-based vaccine administration, in addition to the major hurdles to their en masse implementation, will be examined. EXPERT OPINION: Considering the widely acknowledged disadvantages of current vaccine delivery, such as anxiety, pain, and the requirement for professional administration, a large shift in this research sphere is imminent. The SARS-CoV-2 pandemic has catalyzed the development of alternate vaccination platforms, working to avoid the requirement for mass vaccination centers. As microneedle vaccine patches are transitioning through clinical study phases, research will be required to prepare this technology for a more mass production environment.

Dissolvable polymer microneedles for drug delivery and diagnostics.

Dissolvable transdermal microneedles (µND) are promising micro-devices used to transport a wide selection of active compounds into the skin. To provide an effective therapeutic outcome, µNDs must pierce the human stratum corneum (~10 to 20 µm), without rupturing or bending during penetration, then release their cargo at the predetermined area and time. The ability of dissolvable µND arrays/patches to sufficiently pierce the skin is a crucial requirement, which depends on the material composition, µND geometry and fabrication techniques. This comprehensive review not only provides contemporary knowledge on the µND design approaches, but also the materials science facilitating these delivery systems and the opportunities these advanced materials can provide to enhance clinical outcomes.

Microneedle Patch for Painless Intradermal Collection of Interstitial Fluid Enabling Multianalyte Measurement of Small Molecules, SARS-CoV-2 Antibodies, and Protein Profiling.

Blood sampling is a common practice to monitor health, but it entails a series of drawbacks for patients including pain and discomfort. Thus, there is a demand for more convenient ways to obtain samples. Modern analytical techniques enable monitoring of multiple bioanalytes in smaller samples, opening possibilities for new matrices, and microsampling technologies to be adopted. Interstitial fluid (ISF) is an attractive alternative matrix that shows good correlation with plasma concentration dynamics for several analytes and can be sampled in a minimally invasive and painless manner from the skin at the point-of-care. However, there is currently a lack of sampling devices compatible with clinical translation. Here, to tackle state-of-the-art limitations, a cost-effective and compact single-microneedle-based device designed to painlessly collect precisely 1.1 µL of dermal ISF within minutes is presented. The fluid is volume-metered, dried, and stably stored into analytical-grade paper within the microfluidic device. The obtained sample can be mailed to a laboratory, quantitatively analyzed, and provide molecular insights comparable to blood testing. In a human study, the possibility to monitor various classes of molecular analytes is demonstrated in ISF microsamples, including caffeine, hundreds of proteins, and SARS-CoV-2 antibodies, some being detected in ISF for the first time.

Letting kids play their CARDs (Comfort, Ask, Relax, Distract) to help cope with needle-related fear and pain: Results from user testing.

This study examined perceptions of children and parents about a new web-based CARD (Comfort, Ask, Relax, Distract) game that teaches children how to cope with needle-related pain and fear. A convenience sample of 15 child-parent dyads (children, 6-12 years) participated. Children played the game on a handheld device while being virtually monitored. Activity tracking revealed most children engaged with multiple components. Children reported they understood the game, it was easy to play, they learned coping strategies and believed they could implement them. Children reported lower fear of needles after playing. Parents liked the simplicity and variety of game activities. Most children and parents reported they would use the game or its coping strategies for future needles and would recommend the game. In summary, children and parents found the CARD web game acceptable and appropriate. Future studies can evaluate its effectiveness when integrated into upcoming needle procedures like COVID-19 vaccinations.

What variables should inform needle length choice for deltoid intramuscular injection? A systematic review.

OBJECTIVES: (1) Assess the distribution of skin-to-deltoid-muscle distance (SDMD) at the deltoid intramuscular (IM) injection site; (2) its relationship with demographic and anthropometric variables and (3) Consider the findings in relation to clinical guidance on IM injection, such as COVID-19 vaccines. DESIGN: Systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. DATA SOURCES: MEDLINE, EMBASE, ClinicalTrials.gov, Cochrane Library, CINAHL and SCOPUS between June and July 2021 with no publication date limit. ELIGIBILITY CRITERIA: Studies reporting measurements of the SDMD in living adults aged 16 years and older, at the deltoid IM injection site, published in English were considered. DATA EXTRACTION AND SYNTHESIS: Two independent reviewers performed each stage of screening, data extraction and quality assessments using the Joanna Briggs Institute Critical Appraisal Checklist for analytical cross sectional studies. RESULTS: 16 105 papers were identified, of which 11 studies were suitable for review, representing 1414 participants. Heterogeneity in the definition of the deltoid IM injection site, locations measured and methods of measurement precluded meta-analysis. Evidence from ultrasound SDMD measurements demonstrated some patients in all but 'underweight' body mass index (BMI) categories, may require needles longer than 25 mm for successful IM injection. Calliper measurements overestimated SDMD compared with ultrasound. Female sex, higher BMI categories and greater weight in women were associated with greater SDMD. CONCLUSIONS: The reviewed evidence was insufficient to inform definitive needle length 'cut points' for IM injection based on demographic or anthropomorphic variables. Contemporary clinical guidance currently based on this evidence, including the site of injection and choice of needle length, may result in subcutaneous administration in a small proportion of recipients, particularly if obese or of female sex. PROSPERO REGISTRATION NUMBER: CRD42021264625.

Decision Method of Optimal Needle Insertion Angle for Dorsal Hand Intravenous Robot.

In the context of COVID-19, the research on various aspects of the venipuncture robot field has become increasingly hot, but there has been little research on robotic needle insertion angles, primarily performed at a rough angle. This will increase the rate of puncture failure. Furthermore, there is sometimes significant pain due to the patients' differences. This paper investigates the optimal needle entry angle decision for a dorsal hand intravenous injection robot. The dorsal plane of the hand was obtained by a linear structured light scan, which was used as a basis for calculating the needle entry angle. Simulation experiments were also designed to determine the optimal needle entry angle. Firstly, the linear structured optical system was calibrated and optimized, and the error function was constructed and solved iteratively by the optimization method to eliminate measurement error. Besides, the dorsal hand was scanned to obtain the spatial point clouds of the needle entry area, and the least squares method was used to fit it to obtain the dorsal hand plane. Then, the needle entry angle was calculated based on the needle entry area plane. Finally, the changes in the penetration force under different needle entry angles were analyzed to determine the optimal needle insertion angle. According to the experimental results, the average error of the optimized structured light plane position was about 0.1 mm, which meets the needs of the project, and a large angle should be properly selected for needle insertion during the intravenous injection.

Determination of the location of the needle entry point based on an improved pruning algorithm.

Since the emergence of new coronaviruses and their variant virus, a large number of medical resources around the world have been put into treatment. In this case, the purpose of this article is to develop a handback intravenous intelligence injection robot, which reduces the direct contact between medical staff and patients and reduces the risk of infection. The core technology of hand back intravenous intelligent robot is a handlet venous vessel detection and segmentation and the position of the needle point position decision. In this paper, an image processing algorithm based on U-Net improvement mechanism (AT-U-Net) is proposed for core technology. It is investigated using a self-built dorsal hand vein database and the results show that it performs well, with an F1-score of 93.91%. After the detection of a dorsal hand vein, this paper proposes a location decision method for the needle entry point based on an improved pruning algorithm (PT-Pruning). The extraction of the trunk line of the dorsal hand vein is realized through this algorithm. Considering the vascular cross-sectional area and bending of each vein injection point area, the optimal injection point of the dorsal hand vein is obtained via a comprehensive decision-making process. Using the self-built dorsal hand vein injection point database, the accuracy of the detection of the effective injection area reaches 96.73%. The accuracy for the detection of the injection area at the optimal needle entry point is 96.50%, which lays a foundation for subsequent mechanical automatic injection.

Intradermal delivery of mRNA using cryomicroneedles.

Microneedles can realize the intradermal and transdermal delivery of drugs. However, most conventional microneedles made of metal, polymer and ceramics are unsuitable for the delivery of mRNA drugs that are fragile and temperature-sensitive. This study explores the usage of cryomicroneedles (CryoMNs) for the intradermal delivery of mRNA molecules. Taking luciferase mRNA as an example, we first optimize the formulation of CryoMNs to maximize mRNA stability. Later, in the mouse model, we compare the delivery efficiency with the conventional subcutaneous injection for both the luciferase mRNA and COVID-19 Comirnaty mRNA vaccines, where CryoMNs delivered mRNA vaccines successfully induce specific B-cell antibody, neutralizing activity and T-cell responses. STATEMENT OF SIGNIFICANCE: mRNA vaccines are fragile and temperature-sensitive, so they are mainly delivered by intramuscular injection that often causes pain and requires clinical expertise to immunize patients. Microneedles permit convenient, fast and safe vaccination. However, existing microneedle platforms are ineffective to protect the integrity of mRNA vaccines in fabrication, storage, and administration. This work utilizes cryomicroneedles (CryoMNs) technology to intradermally deliver mRNA. In the mouse model, CryoMNs are compared with the subcutaneous injection for the delivery efficiency of both the luciferase mRNA and COVID-19 Comirnaty mRNA vaccines, where CryoMNs delivered mRNA vaccines successfully produce specific B-cell antibodies, T-cell responses, and neutralizing activity. This work is expected to provide a new delivery strategy for the emerging mRNA therapeutics.

Microneedle-Based Vaccine Delivery: Review of an Emerging Technology.

Vaccination has produced a great improvement to the global health by decreasing/eradicating many infectious diseases responsible for significant morbidity and mortality. Thanks to vaccines, many infections affecting childhood have been greatly decreased or even eradicated (smallpox, measles, and polio). That is why great efforts are made to achieve mass vaccination against COVID-19. However, developed vaccines face many challenges with regard to their safety and stability. Moreover, needle phobia could prevent a significant proportion of the population from receiving vaccines. In this context, microneedles (MNs) could potentially present a solution to address these challenges. MNs represent single dose administration systems that do not need reconstitution or cold-chain storage. Being self-administered, pain-free, and capable of producing superior immunogenicity makes them a more attractive alternative. This review explores microneedles' types, safety, and efficacy in vaccine delivery. Preclinical and clinical studies for microneedle-based vaccines are discussed and patent examples are included.

[Thumb-tack needles based on "Biaoben acupoint compatibility" for sequela of COVID-19 during recovery period].

OBJECTIVE: To observe the effect of thumb-tack needles based on "Biaoben acupoint compatibility" on sequela symptoms, mental state and pulmonary ventilation function in patients with coronavirus disease 2019 (COVID-19) during recovery period. METHODS: Fifty cases of COVID-19 during recovery period were randomly divided into an observation group and a control group, 25 cases in each group. The patients in the observation group were treated with thumb-tack needles at Guanyuan (CV 4), Zusanli (ST 36) and Taiyuan (LU 9). The patients in the control group were treated with sham thumb-tack needles at identical acupoints as the observation group. The treatment in the two groups was given once a day, 7-day treatment was taken as a course of treatment, and totally two courses of treatment were given. The TCM symptom score, Hamilton anxiety scale (HAMA) score, Hamilton depression scale (HAMD) score, pulmonary function (forced vital capacity [FVC], forced expiratory volume in the first second [FEV1], peak expiratory flow [PEF]), the severity of pulmonary ventilation dysfunction and pulmonary imaging changes in the two groups were compared before and after treatment. RESULTS: Compared before treatment, the total scores and each item scores of TCM symptom scale, HAMA scores and HAMD scores in the two groups were reduced after treatment (P<0.05). Except for the symptom scores of dry throat and dry stool, the total score and each item score of TCM symptom scale, HAMA score and HAMD score in the observation group were lower than those in the control group (P<0.05). Compared before treatment, FVC, FEV1 and PEF in the two groups were increased after treatment (P<0.05), and those in the observation group were higher than the control group (P<0.05). The severity of pulmonary ventilation dysfunction in the two groups was reduced after treatment (P<0.05), and the severity in the observation group was better than that in the control group (P<0.05). After treatment, the lung shadow area in the two groups was decreased (P<0.05), and that in the observation group was smaller than the control group (P<0.05). The improvement of imaging change in the observation group was better than that in the control group (P<0.05). CONCLUSION: The thumb-tack needles based on "Biaoben acupoint compatibility" could significantly reduce the sequela symptoms, anxiety and depression in patients with COVID-19 during recovery stage, and improve the pulmonary ventilation function.

Microneedles enable the development of skin-targeted vaccines against coronaviruses and influenza viruses.

Throughout the COVID-19 pandemic, many have seriously worried that the plus burden of seasonal influenza that might create a destructive scenario, resulting in overwhelmed healthcare capacities and onwards loss of life. Many efforts to develop a safe and efficacious vaccine to prevent infection by coronavirus and influenza, highlight the importance of vaccination to combat infectious pathogens. While vaccines are traditionally given as injections into the muscle, microneedle (MN) patches designed to precisely deliver cargos into the cutaneous microenvironment, rich in immune cells, provide a noninvasive and self-applicable vaccination approach, reducing overall costs and improving access to vaccines in places with limited supply. The current review aimed to highlight advances in research on the development of MNs-mediated cutaneous vaccine delivery. Concluding remarks and challenges on MNs-based skin immunization are also provided to contribute to the rational development of safe and effective MN-delivered vaccines against these emerging infectious diseases.

Microneedle arrays integrated with living organisms for smart biomedical applications.

Various living organisms have proven to influence human health significantly, either in a commensal or pathogenic manner. Harnessing the creatures may remarkably improve human healthcare and cure the intractable illness that is challenged using traditional drugs or surgical approaches. However, issues including limited biocompatibility, poor biosafety, inconvenience for personal handling, and low patient compliance greatly hinder the biomedical and clinical applications of living organisms when adopting them for disease treatment. Microneedle arrays (MNAs), emerging as a promising candidate of biomedical devices with the functional diversity and minimal invasion, have exhibited great potential in the treatment of a broad spectrum of diseases, which is expected to improve organism-based therapies. In this review, we systemically summarize the technologies employed for the integration of MNAs with specific living organisms including diverse viruses, bacteria, mammal cells and so on. Moreover, their applications such as vaccination, anti-infection, tumor therapy and tissue repairing are well illustrated. Challenges faced by current strategies, and the perspectives of integrating more living organisms, adopting smarter materials, and developing more advanced technologies in MNAs for future personalized and point-of-care medicine, are also discussed. It is believed that the combination of living organisms with functional MNAs would hold great promise in the near future due to the advantages of both biological and artificial species.

Specific Protein Antigen Delivery to Human Langerhans Cells in Intact Skin.

Immune modulating therapies and vaccines are in high demand, not least to the recent global spread of SARS-CoV2. To achieve efficient activation of the immune system, professional antigen presenting cells have proven to be key coordinators of such responses. Especially targeted approaches, actively directing antigens to specialized dendritic cells, promise to be more effective and accompanied by reduced payload due to less off-target effects. Although antibody and glycan-based targeting of receptors on dendritic cells have been employed, these are often expensive and time-consuming to manufacture or lack sufficient specificity. Thus, we applied a small-molecule ligand that specifically binds Langerin, a hallmark receptor on Langerhans cells, conjugated to a model protein antigen. Via microneedle injection, this construct was intradermally administered into intact human skin explants, selectively loading Langerhans cells in the epidermis. The ligand-mediated cellular uptake outpaces protein degradation resulting in intact antigen delivery. Due to the pivotal role of Langerhans cells in induction of immune responses, this approach of antigen-targeting of tissue-resident immune cells offers a novel way to deliver highly effective vaccines with minimally invasive administration.

An ultra-low-cost electroporator with microneedle electrodes (ePatch) for SARS-CoV-2 vaccination.

Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other pathogens with pandemic potential requires safe, protective, inexpensive, and easily accessible vaccines that can be developed and manufactured rapidly at a large scale. DNA vaccines can achieve these criteria, but induction of strong immune responses has often required bulky, expensive electroporation devices. Here, we report an ultra-low-cost (<1 USD), handheld (<50 g) electroporation system utilizing a microneedle electrode array ("ePatch") for DNA vaccination against SARS-CoV-2. The low cost and small size are achieved by combining a thumb-operated piezoelectric pulser derived from a common household stove lighter that emits microsecond, bipolar, oscillatory electric pulses and a microneedle electrode array that targets delivery of high electric field strength pulses to the skin's epidermis. Antibody responses against SARS-CoV-2 induced by this electroporation system in mice were strong and enabled at least 10-fold dose sparing compared to conventional intramuscular or intradermal injection of the DNA vaccine. Vaccination was well tolerated with mild, transient effects on the skin. This ePatch system is easily portable, without any battery or other power source supply, offering an attractive, inexpensive approach for rapid and accessible DNA vaccination to combat COVID-19, as well as other epidemics.

ECMO implantation training: Needle penetration in 3D printable materials and porcine aorta.

AIM: Patients with cardiogenic shock or ARDS, for example, in COVID-19/SARS-CoV-2, may require extracorporeal membrane oxygenation (ECMO). An ECLS/ECMO model simulating challenging vascular anatomy is desirable for cannula insertion training purposes. We assessed the ability of various 3D-printable materials to mimic the penetration properties of human tissue by using porcine aortae. METHODS: A test bench for needle penetration and piercing in sampled porcine aorta and preselected 3D-printable polymers was assembled. The 3D-printable materials had Shore A hardness of 10, 20, and 50. 17G Vygon 1.0 × 1.4 mm × 70 mm needles were used for penetration tests. RESULTS: For the porcine tissue and Shore A 10, Shore A 20, and Shore A 50 polymers, penetration forces of 0.9036 N, 0.9725 N, 1.0386 N, and 1.254 N were needed, respectively. For piercing through the porcine tissue and Shore A 10, Shore A 20, and Shore A 50 polymers, forces of 0.8399 N, 1.244 N, 1.475 N, and 1.482 N were needed, respectively. ANOVA showed different variances among the groups, and pairwise two-tailed t-tests showed significantly different needle penetration and piercing forces, except for penetration of Shore A 10 and 20 polymers (p = 0.234 and p = 0.0857). Significantly higher forces were required for all other materials. CONCLUSION: Shore A 10 and 20 polymers have similar needle penetration properties compared to the porcine tissue. Significantly more force is needed to pierce through the material fully. The most similar tested material to porcine aorta for needle penetration and piercing in ECMO-implantation is the silicon Shore A 10 polymer. This silicon could be a 3D-printable material in surgical training for ECMO-implantation.

Enhancing influenza vaccine immunogenicity and efficacy through infection mimicry using silk microneedles.

Traditional bolus vaccine administration leads to rapid clearance of vaccine from lymphoid tissue. However, there is increasing evidence suggesting that the kinetics of antigen delivery can impact immune responses to vaccines, particularly when tailored to mimic natural infections. Here, we present the specific enhancements sustained release immunization confers to seasonal influenza vaccine, including the magnitude, durability, and breadth of humoral responses. To achieve sustained vaccine delivery kinetics, we have developed a microneedle array patch (MIMIX), with silk fibroin-formulated vaccine tips designed to embed in the dermis after a short application to the skin and release antigen over 1-2 weeks, mimicking the time course of a natural influenza infection. In a preclinical murine model, a single influenza vaccine administration via MIMIX led to faster seroconversion, response-equivalence to prime-boost bolus immunization, higher HAI titers against drifted influenza strains, and improved protective efficacy upon lethal influenza challenge when compared with intramuscular injection. These results highlight infection mimicry, achieved through sustained release silk microneedles, as a powerful approach to improve existing seasonal influenza vaccines, while also suggesting the broader potential of this platform technology to enable more efficacious next-generation vaccines and vaccine combinations.

Separable Microneedle Patch to Protect and Deliver DNA Nanovaccines Against COVID-19.

The successful control of coronavirus disease 2019 (COVID-19) pandemic is not only relying on the development of vaccines, but also depending on the storage, transportation, and administration of vaccines. Ideally, nucleic acid vaccine should be directly delivered to proper immune cells or tissue (such as lymph nodes). However, current developed vaccines are normally treated through intramuscular injection, where immune cells do not normally reside. Meanwhile, current nucleic acid vaccines must be stored in a frozen state that may hinder their application in developing countries. Here, we report a separable microneedle (SMN) patch to deliver polymer encapsulated spike (or nucleocapsid) protein encoding DNA vaccines and immune adjuvant for efficient immunization. Compared with intramuscular injection, SMN patch can deliver nanovaccines into intradermal for inducing potent and durable adaptive immunity. IFN-γ+CD4/8+ and IL-2+CD4/8+ T cells or virus specific IgG are significantly increased after vaccination. Moreover, in vivo results show the SMN patches can be stored at room temperature for at least 30 days without decreases in immune responses. These features of nanovaccines-laden SMN patch are important for developing advanced COVID-19 vaccines with global accessibility.

Increasing vaccine supply with low dead-volume syringes and needles.

As global vaccine production capacity is limited, every optimization strategy must be explored to rapidly increase the number of people vaccinated. The objective of this study is to determine which medical devices allow the extraction of the maximum number of doses from different vaccine vials (Pfizer-BioNTech, AstraZeneca, Moderna and Johnson & Johnson vaccines) by analyzing all the factors involved in the preparation of the injected doses. By measuring the dead-volume of 32 syringe-needle combinations, we show that fixed-needle syringe with a dead-volume of less than 5 µL can extract up to 7 doses from Pfizer vials, 13 doses from AstraZeneca vials, 12 doses from Moderna vials and 6 doses from Johnson & Johnson vials. We found that the syringe accuracy is important, and can compromise the chances of extracting additional doses when withdrawing too large a volume. For Pfizer vaccine, particular attention must be paid to the choice of dilution syringe, which may compromise the extraction of the 7th dose. The withdrawal of extra doses from vaccine vials was not operator-dependent. In this unprecedented health context, the medical device considerations presented here could help to optimize every COVID-19 vaccine vial.