SERS-Based Microneedle Biosensor for In Situ and Sensitive Detection of Tyrosinase.

Tyrosinase (TYR) emerges as a key enzyme that exerts a regulatory influence on the synthesis of melanin, thereby assuming the role of a critical biomarker for the detection of melanoma. Detecting the authentic concentration of TYR in the skin remains a primary challenge. Distinguished from ex vivo detection methods, this study introduces a novel sensor platform that integrates a microneedle (MN) biosensor with surface-enhanced Raman spectroscopy (SERS) technology for the in situ detection of TYR in human skin. The platform utilized dopamine (DA)-functionalized gold nanoparticles (Au NPs) as the capturing substrate and 4-mercaptophenylboronic acid (4-MPBA)-modified silver nanoparticles (Ag NPs) acting as the SERS probe. Here, the Au NPs were functionalized with mercaptosuccinic acid (MSA) for DA capture. In the presence of TYR, DA immobilized on the MN is preferentially oxidized to dopamine quinone (DQ), a process that results in a decreased density of SERS probes on the platform. TYR concentration was detected through variations in the signal intensity emitted by the phenylboronic acid. The detection system was able to evaluate TYR concentrations within a linear range of 0.05 U/mL to 200 U/mL and showed robust anti-interference capabilities. The proposed platform, integrating MN-based in situ sensing, SERS technology, and TYR responsiveness, holds significant importance for diagnosing cutaneous melanoma.

Statistical estimation of deltoid subcutaneous fat pad thickness: implications for needle length for vaccination.

Current US Centers for Disease Control and Prevention intramuscular injection needle length guidelines for injection fo the deltoid muscle are based on weight and gender. The aims of this study are (1) to evaluate whether other biometric data (age, gender, height, weight and body mass index (BMI)) are better predictors of the thickness of the deltoid subcutaneous fat pad (DSFP) than weight and gender and (2) to evaluate the performance of the CDC weight-based needle length guidelines. This was a retrospective single center cohort study of 386 patients who underwent surveillance PET/CT between 01/01/2020 and 04/01/2021. Patient age, gender, height, weight, BMI and CT measurements of the DSFP were evaluated. DSFP was positively correlated with weight and BMI in men (r = 0.67, P < 0.001; r = 0.74, P < 0.001) and women (r = 0.69, P < 0.001; r = 0.75, P < 0.001) respectively. DSFP was negatively correlated with age in women (r = - 0.19, P = 0.013). Age and BMI were better predictors of DSFP than weight. The best model to predict the DSFP is: [Formula: see text] A 1-inch needle is expected to reach the deltoid in 85.3% of women less than 200 pounds, and 98.6% of men less than 260 pounds. This rate differed between genders (P < 0.001, odds ratio (OR) 0.08, 95% CI (0.02, 0.29)). A 1.5-inch needle is expected to reach the deltoid in 76.7% of women greater than 200 pounds, and 75.0% of men greater than 260 pounds. Current CDC deltoid intramuscular injection needle length guidelines result in women and obese individuals being more likely to receive subcutaneous injections. Age and BMI based guidelines for needle length selection are more accurate.

Axially rigid steerable needle with compliant active tip control.

Steerable instruments allow for precise access to deeply-seated targets while sparing sensitive tissues and avoiding anatomical structures. In this study we present a novel omnidirectional steerable instrument for prostate high-dose-rate (HDR) brachytherapy (BT). The instrument utilizes a needle with internal compliant mechanism, which enables distal tip steering through proximal instrument bending while retaining high axial and flexural rigidity. Finite element analysis evaluated the design and the prototype was validated in experiments involving tissue simulants and ex-vivo bovine tissue. Ultrasound (US) images were used to provide visualization and shape-reconstruction of the instrument during the insertions. In the experiments lateral tip steering up to 20 mm was found. Manually controlled active needle tip steering in inhomogeneous tissue simulants and ex-vivo tissue resulted in mean targeting errors of 1.4 mm and 2 mm in 3D position, respectively. The experiments show that steering response of the instrument is history-independent. The results indicate that the endpoint accuracy of the steerable instrument is similar to that of the conventional rigid HDR BT needle while adding the ability to steer along curved paths. Due to the design of the steerable needle sufficient axial and flexural rigidity is preserved to enable puncturing and path control within various heterogeneous tissues. The developed instrument has the potential to overcome problems currently unavoidable with conventional instruments, such as pubic arch interference in HDR BT, without major changes to the clinical workflow.

An overview on the advantages and limitations of 3D printing of microneedles.

The use of 3D printing (3DP) technology, which has been continuously evolving since the 1980s, has recently become common in healthcare services. The introduction of 3DP into the pharmaceutical industry particularly aims at the development of patient-centered dosage forms based on structure design. It is still a new research direction with potential to create the targeted release of drug delivery systems in freeform geometries. Although the use of 3DP technology for solid oral dosage forms is more preferable, studies on transdermal applications of the technology are also increasing. Microneedle sequences are one of the transdermal drug delivery (TDD) methods which are used to bypass the minimally invasive stratum corneum with novel delivery methods for small molecule drugs and vaccines. Microneedle arrays have advantages over many traditional methods. It is attractive with features such as ease of application, controlled release of active substances and patient compliance. Recently, 3D printers have been used for the production of microneedle patches. After giving a brief overview of 3DP technology, this article includes the materials necessary for the preparation of microneedles and microneedle patches specifically for penetration enhancement, preparation methods, quality parameters, and their application to TDD. In addition, the applicability of 3D microneedles in the pharmaceutical industry has been evaluated.

Safety analysis of percutaneous needle electrolysis: a study of needle composition, morphology, and electrical resistance.

BACKGROUND: Percutaneous needle electrolysis (PNE) consists of a galvanic current combined with the insertion of a solid needle into the tissues of the musculoskeletal system. The application of a galvanic current through a needle can alter the morphology and composition during treatment application. This procedure may also provoke a localized temperature increase. AIM: The aim was to evaluate the safety of the PNE procedure by analyzing possible alterations of the needles employed. METHODS: Physio Invasiva® and AguPunt EPI® brand needles, commonly used for the application of this technique, were analyzed in response to three different treatment protocols. Temperature changes were evaluated with the needles immersed in a test tube containing Ringer's solution, and electrical resistance was evaluated with a multimeter. The morphology of the needles, pre- and post-treatment, was examined with a scanning electron microscope (FEI Quanta 600), and the composition of the needles was evaluated using RX diffusion with Oxford Instruments software. RESULTS: Ringer's solution contained in the test tubes examined did not present temperature changes. No changes were observed in the needles under investigation with respect to electrical resistance, morphology, or composition with a protocol applying 3-mA intensity for 3 s and three applications. However, important morphological alterations were observed that affected needle composition after 50 applications (at 3 mA for 3 s). CONCLUSION: PNE, applied according to conventional protocols, appeared to be safe and athermal, and did not provoke a loss of metal particles or modify the morphology of the needles used when studied in vitro.

The effect of needle size on cerebrospinal fluid collection time and post-dural puncture headache: A retrospective cohort study.

OBJECTIVE: The main objective of this study was to compare cerebrospinal fluid (CSF) collection time and patient's discomfort between 20G (a)traumatic and 22G atraumatic needles. BACKGROUND: Risk of post-dural puncture headache (PDPH) is decreased using atraumatic needles. Smaller needles may give lower risk but possibly at the cost of increased CSF collection time (due to lower flow), leading to additional patient's discomfort. METHODS: We performed a retrospective study of lumbar puncture data from a research program on CSF metabolomics and compared traumatic 20G (n = 210) with atraumatic 20G (n = 39) and 22G (n = 105) needles. In this cohort, incidence of PDPH was prospectively registered with other procedure details. Primary outcome was CSF collection time (time to fill the tube). Secondary outcomes were pain and stress scores during procedure, and incidence of PDPH. RESULTS: The time to collect 10 mL of CSF was longer for 22G needles (6.1 minutes; 95% CI 5.8-6.5) than for 20G traumatic (2.2 minutes; 95% CI 2.1-2.2) and 20G atraumatic needles (2.9 minutes; 95% CI 2.8-3.1). There were no differences in pain and stress scores. PDPH was lower for 22G atraumatic needles: odds ratio 0.41 (95% CI 0.25-0.66) versus 20G traumatic needles and 0.53 (95% CI 0.40-0.69) versus 20G atraumatic needles. Absolute PDPH rates were 69/210 (32.9%) for 20G traumatic, 13/39 (33.3%) for 20G atraumatic, and 19/105 (18.1%) for 22G atraumatic needles. CONCLUSIONS: CSF collection time is slightly longer for smaller 22G needles, but this does not lead to more discomfort for the patient.

Needle Manufacturing, Quality Control, and Optimization for Patient Comfort.

INTRODUCTION: There is an increasing rise of cosmetic injectables. We sought to understand the manufacturing, quality control process, and needle selection of hypodermic needles for fillers. OBJECTIVE: To understand the process of manufacturing and quality control of hypodermic needles and the relevance to an aesthetic clinician. METHODS: We conducted a search of the internet and contacted medical device companies to understand the manufacturing process. We then collaborated with the Executive director of global pharmaceutical technology from Abbvie as well as the packaging and device engineer at Galderma and summarized our findings. Finally, we reviewed the literature and summarized existing recommendations on techniques to minimize pain related to injection. RESULTS: Hypodermic needles undergo an extensive manufacturing and regulatory process. Many considerations are taken into account in needle manufacturing as well as the selection process with commercially available hyaluronic acid filler products. Needle manufacturers are held to universal standards though the International Organization for Standardization (ISO). Filler companies perform their own testing to evaluate suitability of needles for their product including leakage force, penetration force, extrusion force, etc. Finally, parameters such as needle length, needle diameter, and wall thickness are considered for selection of needle/hub with individual filler viscosity. CONCLUSION: There is extensive consideration that goes into needle manufacturing, quality control, and optimization for hyaluronic acid filler. Understanding the technical process helps inform the clinician and guide patient care for maximum comfort. J Drugs Dermatol. 2021;20(1):44-48. doi:10.36849/JDD.5591.

An accurate and dual-effective body slimming method through a soluble microneedle patch with variable temperature.

Obesity is a chronic and recurrent disease with potential risks. Traditional weight-loss methods (like exercises, surgeries, oral drugs, etc.) have shown different side effects. In this experiment, the microneedle (MN) patch was selected as the drug carrier of the weight-loss drug Rosiglitazone (Rosi). Besides, melanin was added to enhance the photo-thermal effect and accelerate the release of drugs to the target fat region under near-infrared (NIR) light. Afterwards, with exterior cold stimulation, the significant and accurate effect of body slimming could be achieved. This combination of soluble MN patches and variable temperatures provides an attractive nonsurgical method for future accurate body slimming management.

A Comparative Study of 22G versus 19G Needles for EUS-Guided Biopsies for Parenchymal Liver Disease: Are Thinner Needles Better?

BACKGROUND AND AIMS: Data on comparative efficacy of various available endoscopic ultrasound-guided liver biopsy (EUS-LB) needles are limited. We sought to compare the performance of a novel Franseen-tip 22G fine-needle biopsy (FNB) device to that of 19G needle platforms for liver parenchyma. METHODS: Consecutive patients referred for EUS and suspected to have hepatic parenchymal disease underwent EUS-LB using different EUS needles and were included in this retrospective study. Two blinded expert liver pathologists independently reviewed and reported on: total number of tissue fragments, length of longest fragment, number of complete and incomplete portal tracts (CPT and IPT), and specimen adequacy. RESULTS: A 22G Franseen-tip needle (A) was used in 30 patients; 19G Tru-Cut needle (B) in 50 patients; 19G reverse beveled non-Tru-Cut needle (C) in 27 patients; and a 19G flexible non-Tru-Cut needle (D) in 28 patients. In the order of needles, A, B, C and D, > 10 tissue fragments were obtained in 100%, 6%, 82%, and 96% samples, the mean number of CPTs was 6.9; 3.0; 7.3; and 16.9, length of longest fragment was 3.8, 4. 7, 3.9, and 8.4 mm, and specimen adequacy was 66.7%, 46%, 82.1%, and 81.5%, respectively. A positive correlation was obtained between number of CPTs and length of longest fragment in samples accrued by 19G needles. CONCLUSION: EUS-LB specimens using 22G Franseen-tip needle appear highly fragmented, leading to inferior specimen adequacy compared to 19G non-Tru-Cut needles. We also report on using length of longest fragment as an additional criterion for specimen adequacy as it positively correlates with number of CPTs standard.

Electrospinning/electrospraying coatings for metal microneedles: A design of experiments (DOE) and quality by design (QbD) approach.

The research presented here shows QbD implementation for the optimisation of the key process parameters in electrohydrodynamic atomisation (EHDA). Here, the electrosprayed nanoparticles and electrospun fibers consisting of a polymeric matrix and dye. Eight formulations were assessed consisting of 5% w/v of polycaprolactone (PCL) in dichloromethane (DCM) and 5% w/v polyvinylpyrrolidone (PVP) in ethanol. A full factorial DOE was used to assess the various parameters (applied voltage, deposition distance, flow rate). Further particle and fiber analysis using Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), particle/fiber size distribution. In addition to this in vitro release studied were carried out using fluorescein and Rhodamine B as model dyes and in vitro permeation studies were applied. The results show a significant difference in the morphology of resultant structures as well as a more rapid release profile for the PVP particles and fibers in comparison to the sustained release profiles found with PCL. In vitro drug release studies showed 100% drug release after 7 days for PCL particles and showed 100% drug release within 120 min for PVP particles. The release kinetics and the permeation study showed that the MN successfully pierced the membrane and the electrospun MN coating released a large amount of the loaded drug within 6 h. This study has demonstrated the capability of these robust MNs to encapsulate a diverse range drugs within a polymeric matrix giving rise to the potential of developed personalised medical devices.

[A new design puncture needle and a device of microcatheter protection for lumbar intrathecal catheterization in rats].

Objective: To introduce a new design needle and a device of microcatheter protection for lumbar intrathecal catheterization in rats,and evaluate its feasibility and effectiveness.Methods: Sixty pathogen-free adult male Sprogue-Dawley rats were randomly divided into two groups(n=30 in each group), the control group (group C) and the modification group(group M). The traditional puncture device, 20G needle, was used in the group C without extemal shielding protection. The new design puncture needle and the microinjection cock were used in the group M. All rats were assessed for motor function on postoperative. The motor function was evaluated 1 day afteroperation. Lidocaine was injected in the catheter at 1st,3rd,7th,14th,21st day post-catheterization, methylene blue was injected in intrathecal at 30th day after operation, and the catheter location was observed. The paw withdrawal threshold(PWT) was measured at 1st,3rd,7th,14th,21st,30th day after operation, open-field test was tested at preoperative and one week postoperative for the purpose of evaluating the autonomous behavior of rats. Results: About motor function:level Ⅰ 75.9%,level Ⅱ 20.7%,level Ⅲ 3.4% in group C, and level Ⅰ 96.7%,level Ⅱ 3.3% in group M, Compared with group C,group M had higher percentage of the level Ⅰ in motor function (P＜0.05);Lidocaine test and methylen blue location showed that each one case of catheter was removed on the 14th and 21st day after intubation in group C, and total four cases were removed till the 30th day, while all catheters were in normal location in group M. There was significant difference between two groups in protection of the extemal portion of catheter(P＜0.05); The time of intrathecal injection in group M was only 1 minute, and it spent more than 3 minutes in group C. Compared with group C,the time of intrathecal injection is significantly shorter in group M(P＜0.01);PWT was reduced to the lowest on the third day after catheterization, and there was significant difference compared with preoperative(P＜0.05), PWT recovered on the 7th day and there were no significant difference between two groups; Compared with preoperative, there was no significant difference in the parameters of the group M in the open field test, neither between two groups. Conclusion: The new design puncture needle by its less injury and higher efficiency can be used in intrathecal catheterization. The microinjection cock is reliable and convenient for repeat injection with a perfect protection function of the external portion of catheter, meanwhile it has no impact on rats' autonomous behavior so that it is worthy of further promoting.

Peripheral venous access using devices over needles with and without extension: costs and outcomes.

OBJECTIVES: to analyze the mean direct cost and peripheral venous access length outcomes using devices over needle with and without extension. METHODS: quantitative, exploratory-descriptive research. Venous punctures and length of the devices were followed. The mean direct cost was calculated by multiplying the time (timed) spent by nursing professionals by the unit cost of labor, adding to the cost of materials. RESULTS: the total mean direct cost of using devices "with extension" (US$ 9.37) was 2.9 times the cost of using devices "without extension" (US$ 4.50), US$ 7.71 and US$ 2.66, respectively. Totaling 96 hours of stay, the "device over needle with extension" showed a lower occurrence of accidental loss. CONCLUSIONS: the use of the "device over needle with extension", despite its higher mean direct cost, was more effective in favoring adequate length of peripheral venous access.

Endoscopic Ultrasound-Guided Fine Needle Biopsy Using 22-Gauge Franseen Needle for the Histological Diagnosis of Solid Lesions: A Multicenter Prospective Pilot Study.

BACKGROUND: Recently, a novel 22-gauge needle with three symmetric needle points and crown-shaped cutting heels, known as a Franseen needle, has been developed for endoscopic ultrasound-guided fine needle biopsy (EUS-FNB). AIM: To assess the histological material acquisition rate and histological diagnostic capability of the 22-gauge Franseen needle (AC22) during EUS-FNB for solid lesions. METHODS: This study was designed as an open-label, multicenter, prospective, single-arm pilot study of EUS-FNB using AC22 for the diagnosis of solid lesions. Three passes of FNB using AC22 were performed for all lesions. The primary endpoints were the histological material acquisition rate and histological diagnostic capability. The secondary endpoints were the technical success rate, quality of histological samples, number of passes for diagnosis, and safety. RESULTS: Between September 2017 and May 2018, 75 patients were enrolled. The final diagnoses were malignancy in 65 and benign in 10. Three passes of FNB were technically successful in all patients. The sensitivity, specificity, and accuracy for the malignancy of histological analyses were 92.3% (60/65), 100% (10/10), and 93.3% (70/75), respectively, for the first pass and 95.4% (62/65), 100% (10/10), and 96% (72/75), respectively, for combined three passes. The diagnostic yield plateaued after the second pass. Sufficient tissue samples for histological interpretation were obtained in 96% (72/75) and 100% (75/75) patients for the single pass and combined three passes, respectively. Two patients (2.7%) developed mild pancreatitis as an adverse event. CONCLUSION: EUS-FNB using AC22 showed high histological diagnostic capability with the high first pass yield. CLINICAL TRIALS REGISTRY: UMIN Clinical Trials Registry (UMIN ID: UMIN000036641).

Medical injection and access to sterile injection equipment in low- and middle-income countries: a meta-analysis of Demographic and Health Surveys (2010-2017).

BACKGROUND: Unsafe injection practices contribute to increased risks of blood-borne infections, including human immunodeficiency virus, hepatitis B and hepatitis C viruses. The aim of this study was to estimate the prevalence of medical injections as well as assess the level of access to sterile injection equipment by demographic factors in low- and middle-income countries (LMICs). METHODS: We carried out a meta-analysis of nationally representative Demographic and Health Surveys (DHSs) conducted between 2010 and 2017 in 39 LMICs. Random effects meta-analysis was used in estimating pooled and disaggregated prevalence. All analyses were conducted using Stata version 14 and Microsoft Excel 2016. RESULTS: The pooled 12-month prevalence estimate of medical injection was 32.4% (95% confidence interval 29.3-35.6). Pakistan, Rwanda and Myanmar had the highest prevalence of medical injection: 59.1%, 56.4% and 53.0%, respectively. Regionally, the prevalence of medical injection ranged from 13.5% in west Asia to 42.7% in south and southeast Asia. The pooled prevalence of access to sterile injection equipment was 96.5%, with Pakistan, Comoros and Afghanistan having comparatively less prevalence: 86.0%, 90.3% and 90.9%, respectively. CONCLUSIONS: Overuse of medical injection and potentially unsafe injection practices remain a considerable challenge in LMICs. To stem the tides of these challenges, national governments of LMICs need to initiate appropriate interventions, including education of stakeholders, and equity in access to quality healthcare services.

Use of a Predictive Regression Model for Estimating Hold-Up Volume for Biologic Drug Product Presentations.

A drug delivery system is designed to administer a therapeutic dose according to its label claim. Upon delivery of a parenteral drug product, the volume remaining inside the container that cannot be extracted at the end of drug administration is called the hold-up volume (HUV) and is primarily considered product wastage. To meet the label claim, every drug product container is filled with a slight excess volume. For early-stage products in clinical phase, for which material availability is often a limitation, excess volume in drug product containers has to be determined experimentally using several grams of product. In such scenarios, established models that can predict HUV in primary drug product containers would be valuable for product development. The objective of this study was to determine HUV with 95% confidence intervals across various container closures and drug delivery systems by using aqueous PEG 400 solution mimicking the viscosity of biologic drug products. ISO 2R, 6R, and 10R vials and single-use hypodermic syringes attached to a Luer lock needle (25 gauge, 1½ in.) were used to mimic parenteral drug product container and delivery systems for determination of HUV. Glass prefilled syringes in 1 mL and 2.25 mL configurations were also used to determine HUV with 95% confidence intervals. A linear regression model was developed for determination of HUV as a function of viscosity and as a function of container closure and a needle-based delivery system. This model predicting HUV was confirmed by using monoclonal antibodies of varying formulations and viscosities for container closure and delivery systems tested in this study. The model provided here can be used to determine HUV for a particular container closure for a drug solution with known viscosity that can subsequently be used to evaluate fill volume specifications and label claim for a dosage form.

Peripheral venous access using devices over needles with and without extension: costs and outcomes / Acceso venoso periférico utilizando dispositivos de aguja con y sin extensión: costos y resultados / Acesso venoso periférico utilizando dispositivos sobre agulha com e sem extensão: custos e desfechos

ABSTRACT Objectives: to analyze the mean direct cost and peripheral venous access length outcomes using devices over needle with and without extension. Methods: quantitative, exploratory-descriptive research. Venous punctures and length of the devices were followed. The mean direct cost was calculated by multiplying the time (timed) spent by nursing professionals by the unit cost of labor, adding to the cost of materials. Results: the total mean direct cost of using devices "with extension" (US$ 9.37) was 2.9 times the cost of using devices "without extension" (US$ 4.50), US$ 7.71 and US$ 2.66, respectively. Totaling 96 hours of stay, the "device over needle with extension" showed a lower occurrence of accidental loss. Conclusions: the use of the "device over needle with extension", despite its higher mean direct cost, was more effective in favoring adequate length of peripheral venous access.

RESUMEN Objetivos: analizar el costo directo promedio y los resultados de permanencia del acceso venoso periférico, utilizando dispositivos de aguja con y sin extensión. Métodos: investigación cuantitativa, exploratoria descriptiva. Se siguieron los pinchazos venosos y el tiempo de permanencia de los dispositivos. El costo directo promedio se calculó multiplicando el tiempo (cronometrado) dedicado por los profesionales de enfermería por el costo unitario de la mano de obra, lo que se suma al costo de los materiales. Resultados: el costo directo promedio total de usar dispositivos "extendidos" (US$ 9,37) fue 2,9 veces el costo de usar dispositivos "no extendidos" (US$ 4,50) de materiales, US$ 7.71 y US$ 2.66, respectivamente. Con un total de 96 horas de estadía, el "dispositivo de aguja extendida" mostró una menor ocurrencia de pérdida accidental. Conclusiones: a pesar del costo directo promedio más alto, el uso de un "dispositivo de aguja extendida" fue más efectivo para favorecer un tiempo de acceso venoso periférico adecuado.

RESUMO Objetivos: analisar o custo direto médio e os desfechos de permanência de acesso venoso periférico, utilizando dispositivos sobre agulha com e sem extensão. Métodos: pesquisa quantitativa, exploratório-descritiva. Acompanharam-se as punções venosas e o tempo de permanência dos dispositivos. Calculou-se o custo direto médio multiplicando-se o tempo (cronometrado) despendido por profissionais de enfermagem pelo custo unitário da mão de obra, somando-se ao custo dos materiais. Resultados: o custo direto médio total do uso de dispositivo "com extensão" (US$ 9,37) foi 2,9 vezes do que o custo do uso de dispositivo "sem extensão" (US$ 4,50), destacando-se os custos dos materiais, US$ 7,71 e US$ 2,66, respectivamente. Totalizando 96 horas de permanência, o "dispositivo sobre agulha com extensão" apresentou menor ocorrência de perda acidental. Conclusões: o uso do "dispositivo sobre agulha com extensão", apesar do maior custo direto médio, foi mais eficaz para favorecer o adequado tempo de permanência do acesso venoso periférico.

Transdermal Microneedles-A Materials Perspective.

Transdermal drug delivery is an emerging field in the pharmaceutical remit compared with conventional methods (oral and parenteral). Microneedle (MN)-based devices have gained significant interest as a strategy to overcome the skin's formidable barrier: the stratum corneum. This approach provides a less invasive, more efficient, patient friendly method of drug delivery with the ability to incorporate various therapeutic agents including macromolecules (proteins and peptides), anti-cancer agents and other hydrophilic and hydrophobic compounds. This short review attempts to assess the various materials involved in the fabrication of MNs as well as incorporation of other excipients to improve drug delivery for novel medical devices. The focus will be on polymers, metals and other inorganic materials utilised for MN drug delivery, as well as their application, limitations and future work to be carried out.

Residual strain effects in needle-induced cavitation.

Needle-induced cavitation (NIC) locally probes the elastic and fracture properties of soft materials, such as gels and biological tissues. Current NIC protocols tend to overestimate properties when compared to traditional techniques. New NIC methods are needed in order to address this issue. NIC measurements consist of two distinct processes, namely (1) the needle insertion process and (2) the cavitation process. The cavitation process is hypothesized to be highly dependent on the initial needle insertion process due to the influence of residual strain below the needle. Retracting the needle before pressurization to a state in which a cylindrical, tube-like fracture is left below the needle tip is experimentally demonstrated to reduce the impact of residual strain on NIC. Verification of the critical cavitation pressure equation in this new geometry is necessary before implementing this retraction NIC protocol. Complementary modeling shows that the change in initial geometry has little effect on the critical cavitation pressure. Together, these measurements demonstrate that needle retraction is a viable experimental protocol for reducing the influence of residual strain, thus enabling the confident measurement of local elastic and fracture properties in soft gels and tissues.

Needle electromyography: Basic concepts.

Needle electromyography (EMG) is the technique of recording and analyzing the electrical signals derived from individual muscle fibers of motor units, at rest and during voluntary contraction, using a needle recording electrode inserted into the muscle. Needle EMG entails inserting a needle electrode into a muscle, recording and amplifying the electrical signals generated from resting or contracting muscle fibers, and interpreting the signals to determine the function of the muscle fibers and motor units. Many factors affect the recorded signals during needle EMG, including the types of needle electrodes and filters and amplifier settings. Different semiquantitative and quantitative methods of analysis of the recorded signals are available, each with advantages and disadvantages. While needle EMG is a safe technique, potential risks include pain, bleeding, and pneumothorax.