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Aaron Calodney,1 Nomen Azeem,2 Patrick Buchanan,3 Ioannis Skaribas,4 Ajay Antony,5 Christopher Kim,6 George Girardi,7 Chau Vu,8 Christopher Bovinet,9 Rainer Vogel,10 Sean Li,11 Navdeep Jassal,12 Youssef Josephson,13 Timothy Lubenow,14 Christopher M Lam,15 Timothy R Deer6 1Precision Spine Care, Tyler, TX, USA; 2Florida Spine and Pain Specialists, Tampa, FL, USA; 3Spanish Hills Interventional Pain Specialists, Camarillo, CA, USA; 4Expert Pain P.A, Houston, TX, USA; 5The Orthopaedic Institute, Gainesville, FL, USA; 6The Spine and Nerve Center, Charleston, WV, USA; 7Front Range Pain Medicine, Fort Collins, CO, USA; 8Evolve Restoration Center, Santa Rosa, CA, USA; 9The Spine Center of Southeast Georgia, Brunswick, GA, USA; 10Comprehensive and Interventional Pain Management, Henderson, NV, USA; 11Premier Pain Centers, Shrewsbury, NJ, USA; 12Excel Pain and Spine, Lakeland, FL, USA; 13The Pain Management Center, Voorhees Township, NJ, USA; 14Rush University Medical Center, Chicago, IL, USA; 15University of Kansas Medical Center, Kansas City, KS, USACorrespondence: Aaron Calodney, Precision Spine Care, Tyler, TX, USA, Email aaroncalodney@me.comIntroduction: Research suggests that sacroiliac joint (SIJ) dysfunction is responsible for 15% to 30% of reported low back pain cases. Recently, there has been an increasing interest in SIJ fusion using minimally invasive surgery (MIS) due to safety. Initially, devices designed for MIS were intended for lateral approaches. A minimally invasive sacroiliac fusion implant for use with a posterior approach has been developed and is regulated for clinical use under the regulatory framework required for human cells, tissues, or cellular or tissue-based products (HCT/Ps).Methods: A multi-center, prospective, single-arm study was launched after initial studies provided preliminary data to support safety, efficacy, and durability of this minimally invasive sacroiliac posterior fusion LinQ allograft implant (NCT04423120). Preliminary results were reported previously. Final results for the full participant cohort are presented here.Results: One-hundred and fifty-nine (159) participants were enrolled across 16 investigational sites in the US between January 2020 and March 2022. One-hundred and twenty-two (122) participants were implanted. At the 1-month follow-up, 82 participants satisfied all criteria for the composite responder endpoint, representing 73.2% of the study cohort. These results stayed consistent across the remaining study timepoints with 66.0%, 74.4%, and 73.5% of participants classified as responders at the 3-, 6- and 12-month follow-up visits, respectively. VAS scores were significantly reduced (p < 0.0001) and ODI scores were significantly improved (p < 0.0001). All domains of the PROMIS-29 were also significantly improved (all p’s < 0.0001). Only one procedure-related serious AE was reported in the study.Conclusion: These results suggest that the posterior approach LinQ Implant System is a safe and effective treatment for sacroiliac joint dysfunction at 12 months, with results that are favorable compared to outcomes reported for an FDA-cleared lateral approach.Keywords: sacroiliac joint disease, sacroiliac fusion, single point posterior fusion, back pain, minimally invasive spine surgery, sacroiliitis

Anuj Shah,1 Jonathan M Hagedorn,2 Usman Latif,3 Ashley Bailey-Classen,4 Nomen Azeem,5 Douglas P Beall,6 Pankaj Mehta,7 Chad Stephens,8 Larry Khoo,9 Timothy Ray Deer10 1Department of Physical Medicine and Rehabilitation, Detroit Medical Center, Detroit, MI, USA; 2Department of Anesthesiology and Perioperative Medicine, Division of Pain Medicine, Mayo Clinic, Rochester, MN, USA; 3Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS, USA; 4Trinity Pain Medicine Associates, Fort Worth, TX, USA; 5Florida Spine & Pain Specialists, Riverview, FL, USA; 6Comprehensive Specialty Care, Edmond, OK, USA; 7Pain Specialists of Austin and Central Texas Pain Center, Austin, TX, USA; 8Noble Pain Management and Sports Medicine, Southlake, TX, USA; 9The Spine Clinic of Los Angeles, Los Angeles, CA, USA; 10The Spine and Nerve Center of the Virginias, Charleston, WV, USACorrespondence: Anuj Shah, Department of Physical Medicine and Rehabilitation, Detroit Medical Center, 261 Mack Ave, Detroit, MI, 48220, USA, Tel +1 734646-0321, Email Anujshah74@gmail.comIntroduction: Lumbar spinal stenosis (LSS) is a common condition caused by degenerative changes in the lumbar spine with age. LSS is caused by a variety of factors, including degenerative spondylosis and spondylolisthesis. People suffering with LSS experience neurogenic claudication, which causes severe physical limitations, discomfort, and a decrease in quality of life. Less invasive procedures are now being researched to improve the prognosis, success rate, and safety of LSS treatments. Posterior lateral spinal arthrodesis (PLSA) is a new surgical treatment for LSS. This study looks at the procedural and patient safety of PLSA.Materials and methods: This study is a multicenter retrospective analysis of the safety of PLSA who met the clinical indications for PLSA and underwent the procedure at eight interventional spine practices. Data was collected on demographical information, pre-procedural numeric rating scale score (NRS), post-procedural NRS, and complication reporting. Patients who were included had LSS with or without spondylolisthesis and had failed conservative treatments. A descriptive statistical analysis was performed to report the outcomes. Results were reported as mean and standard deviations for continuous outcomes, and frequency (%) for categorical outcomes.Results: This retrospective analysis involved 191 patients and 202 PLSA implants. The majority of patients were male Caucasians with a mean age of 69.2 years and a BMI of 31.1. A large majority of implants were placed at the L4-5 level, and the average pre-procedural NRS was 6.3 while the average post-procedural NRS was 3.1, indicating a 50.8% reduction in pain (p < 0.0001). Two patients reported complications, but they were unrelated to the device or surgical procedure; no infections, device malfunctions, or migrations were reported in the patient cohort.Conclusion: Preliminary results with PLSA implants indicate that it is a safe treatment option for patients with moderate LSS who do not respond to conservative management.Keywords: lumbar spinal stenosis, spondylolisthesis, interspinous fusion, Minuteman, spinal simplicity, posterior lateral spinal arthrodesis

Dawood Sayed,1 Jay Grider,2 Natalie Strand,3 Jonathan M Hagedorn,4 Steven Falowski,5 Christopher M Lam,1 Vinicius Tieppo Francio,6 Douglas P Beall,7 Nestor D Tomycz,8 Justin R Davanzo,9 Rohit Aiyer,10 David W Lee,11 Hemant Kalia,12,13 Soun Sheen,13 Mark N Malinowski,14,15 Michael Verdolin,16 Shashank Vodapally,17 Alexios Carayannopoulos,18– 20 Sameer Jain,21 Nomen Azeem,22,23 Reda Tolba,24,25 George C Chang Chien,26,27 Priyanka Ghosh,28 Anthony J Mazzola,29 Kasra Amirdelfan,30 Krishnan Chakravarthy,31,32 Erika Petersen,33 Michael E Schatman,34,35 Timothy Deer36 1Department of Anesthesiology and Pain Medicine, The University of Kansas Medical Center, Kansas City, KS, USA; 2University of Kentucky, Lexington, KY, USA; 3Interventional Pain Management, Mayo Clinic, Scottsdale, AZ, USA; 4iSpine Pain Physicians, Maple Grove, MN, USA; 5Functional Neurosurgery, Neurosurgical Associates of Lancaster, Lancaster, PA, USA; 6Department of Rehabilitation Medicine, University of Kansas Medical Center, Kansas City, KS, USA; 7Comprehensive Specialty Care, Edmond, OK, USA; 8AHN Neurosurgery, Allegheny General Hospital, Pittsburgh, PA, USA; 9AHN Neurosurgery, Forbes Hospital, Monroeville, PA, USA; 10Interventional Pain Management and Pain Psychiatry, Henry Ford Health System, Detroit, MI, USA; 11Physical Medicine & Rehabilitation and Pain Medicine, Fullerton Orthopedic Surgery Medical Group, Fullerton, CA, USA; 12Rochester Regional Health System, Rochester, NY, USA; 13Department of Physical Medicine & Rehabilitation, University of Rochester, Rochester, NY, USA; 14Adena Spine Center, Adena Health System, Chillicothe, OH, USA; 15Ohio University Heritage College of Osteopathic Medicine, Athens, OH, USA; 16Anesthesiology and Pain Medicine, Pain Consultants of San Diego, San Diego, CA, USA; 17Physical Medicine and Rehabilitation, Michigan State University, East Lansing, MI, USA; 18Department of Physical Medicine and Rehabilitation, Rhode Island Hospital, Newport Hospital, Lifespan Physician Group, Providence, RI, USA; 19Comprehensive Spine Center at Rhode Island Hospital, Newport Hospital, Providence, RI, USA; 20Neurosurgery, Brown University, Providence, RI, USA; 21Interventional Pain Management, Pain Treatment Centers of America, Little Rock, AR, USA; 22Department of Neurology, University of South Florida, Tampa, FL, USA; 23Florida Spine & Pain Specialists, Riverview, FL, USA; 24Pain Management, Cleveland Clinic, Abu Dhabi, United Arab Emirates; 25Anesthesiology, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA; 26Pain Management, Ventura County Medical Center, Ventura, CA, USA; 27Center for Regenerative Medicine, University Southern California, Los Angeles, CA, USA; 28Remedy Medical Group, San Francisco, CA, USA; 29Mount Sinai Health System, New York City, NY, USA; 30IPM Medical Group, Inc., Walnut Creek, CA, USA; 31Division of Pain Medicine, Department of Anesthesiology, University of California San Diego, San Diego, CA, USA; 32Va San Diego Healthcare, San Diego, CA, USA; 33Department of Neurosurgery, University of Arkansas for Medical Science, Little Rock, AR, USA; 34Department of Anesthesiology, Perioperative Care, and Pain Medicine, NYU Grossman School of Medicine, New York, New York, USA; 35Department of Population Health - Division of Medical Ethics, NYU Grossman School of Medicine, New York, New York, USA; 36The Spine and Nerve Center of the Virginias, Charleston, WV, USACorrespondence: Dawood Sayed, The University of Kansas Health System, 3901 Rainbow Blvd, Kansas City, KS, 66160, USA, Tel +1 913-588-5521, Email dsayed@kumc.eduIntroduction: Painful lumbar spinal disorders represent a leading cause of disability in the US and worldwide. Interventional treatments for lumbar disorders are an effective treatment for the pain and disability from low back pain. Although many established and emerging interventional procedures are currently available, there exists a need for a defined guideline for their appropriateness, effectiveness, and safety.Objective: The ASPN Back Guideline was developed to provide clinicians the most comprehensive review of interventional treatments for lower back disorders. Clinicians should utilize the ASPN Back Guideline to evaluate the quality of the literature, safety, and efficacy of interventional treatments for lower back disorders.Methods: The American Society of Pain and Neuroscience (ASPN) identified an educational need for a comprehensive clinical guideline to provide evidence-based recommendations. Experts from the fields of Anesthesiology, Physiatry, Neurology, Neurosurgery, Radiology, and Pain Psychology developed the ASPN Back Guideline. The world literature in English was searched using Medline, EMBASE, Cochrane CENTRAL, BioMed Central, Web of Science, Google Scholar, PubMed, Current Contents Connect, Scopus, and meeting abstracts to identify and compile the evidence (per section) for back-related pain. Search words were selected based upon the section represented. Identified peer-reviewed literature was critiqued using United States Preventive Services Task Force (USPSTF) criteria and consensus points are presented.Results: After a comprehensive review and analysis of the available evidence, the ASPN Back Guideline group was able to rate the literature and provide therapy grades to each of the most commonly available interventional treatments for low back pain.Conclusion: The ASPN Back Guideline represents the first comprehensive analysis and grading of the existing and emerging interventional treatments available for low back pain. This will be a living document which will be periodically updated to the current standard of care based on the available evidence within peer-reviewed literature.Keywords: back pain, intervention, clinical guideline, spinal cord stimulation, minimally invasive spine procedure, lumbar disorder, epidural steroid injection, radiofrequency ablation

Natalie Strand,1 Ryan S D’Souza,2 Jonathan M Hagedorn,3 Scott Pritzlaff,4 Dawood Sayed,5 Nomen Azeem,6 Alaa Abd-Elsayed,7 Alexander Escobar,8 Mark A Huntoon,9 Christopher M Lam,5 Timothy R Deer10 1Department of Anesthesiology, Division of Pain Medicine, Mayo Clinic, Scottsdale, AZ, USA; 2Department of Anesthesiology and Perioperative Medicine, Division of Pain Medicine, Mayo Clinic, Rochester, MN, USA; 3iSpine Pain Physicians, Burnsville, MN, USA; 4Department of Anesthesiology and Pain Medicine, Division of Pain Medicine, University of California-Davis, Sacramento, CA, USA; 5The University of Kansas Medical Center, Kansas City, KS, USA; 6Florida Spine & Pain Specialists, Bradenton, FL, USA; 7Department of Anesthesiology, University of Wisconsin, Madison, WI, USA; 8Comprehensive Centers for Pain Management, Toledo, OH, USA; 9Department of Anesthesiology, Virginia Commonwealth University, Henrico, VA, USA; 10The Spine and Nerve Center of the Virginias, Charleston, WV, USACorrespondence: Natalie Strand, Department of Anesthesiology, Division of Pain Medicine, Mayo Clinic, Scottsdale, AZ, USA, Tel +1 480-301-8000, Fax +1 480-342-2986, Email strand.natalie@mayo.eduAbstract: The objective of this peripheral nerve stimulation consensus guideline is to add to the current family of consensus practice guidelines and incorporate a systematic review process. The published literature was searched from relevant electronic databases, including PubMed, Scopus, Cochrane Central Register of Controlled Trials, and Web of Science from database inception to March 29, 2021. Inclusion criteria encompassed studies that described peripheral nerve stimulation in patients in terms of clinical outcomes for various pain conditions, physiological mechanism of action, surgical technique, technique of placement, and adverse events. Twenty randomized controlled trials and 33 prospective observational studies were included in the systematic review process. There is Level I evidence supporting the efficacy of PNS for treatment of chronic migraine headaches via occipital nerve stimulation; chronic hemiplegic shoulder pain via stimulation of nerves innervating the trapezius, supraspinatus, and deltoid muscles; failed back surgery syndrome via subcutaneous peripheral field stimulation; and lower extremity neuropathic and lower extremity post-amputation pain. Evidence from current Level I studies combined with newer technologies facilitating less invasive and easier electrode placement make peripheral nerve stimulation an attractive alternative for managing patients with complex pain disorders. Peripheral nerve stimulation should be used judiciously as an adjunct for chronic and acute postoperative pain following adequate patient screening and positive diagnostic nerve block or stimulation trial.Keywords: post-amputation pain, low back pain, peripheral neuropathy, chronic postoperative pain

Dawood Sayed,1 Nasir Khatri,1 Adam Rupp,1 Christopher Bovinet,2 Nomen Azeem,3 Sean Li,4 Youssef Josephson,5 Jason Pope6 1Department of Anesthesiology, University of Kansas, Kansas City, KS, USA; 2The Spine Center of Southeast Georgia, Brunswick, GA, USA; 3Florida Spine & Pain Specialists, Riverview, FL, USA; 4Premier Pain Centers, Shrewsbury, NJ, USA; 5National Spine & Pain Centers, Voorhees Township, NJ, USA; 6Evolve Restorative Center, Santa Rosa, CA, USACorrespondence: Dawood Sayed, Department of Anesthesiology, University of Kansas, Kansas City, KS, USA, Email dsayed1@yahoo.comBackground: Studies have found that up to one-third of patients with LBP have sacroiliac joint (SIJ) dysfunction as a contributing cause. Historically, the management of SIJ dysfunction has been plagued by ineffectiveness or significant morbidity. In 2008, minimally invasive lateral SIJ fusion was developed. While this procedure is a safe and effective treatment, there is still a significant proportion of patients who will not experience therapeutic success. There is a paucity of data in the literature regarding the management of these patients. Recently, a novel posterior sacroiliac joint fusion device has been developed which minimizes complications compared to lateral approaches and may serve to salvage therapeutic failures in this patient population.Objective: Determine the efficacy and feasibility of a posterior SIJ fusion device as a salvage technique in patients who have not experienced therapeutic success following lateral SIJ fusion.Design: Multi-center retrospective observational study.Methods: Patients who had previously undergone lateral SIJ fusion and had persistent LBP were evaluated and diagnosed to have persistent primary SIJ pathology. All patients underwent posterior SIJ fusion utilizing a machined allograft transfixing sacroiliac fusion device. Demographic data and patient reported pain scores were collected.Results: A total of 7 patients who had undergone lateral SIJ fusion were included in the study and underwent posterior SIJ fusion. The mean patient reported pain improvement following posterior fusion was 80% with an average follow-up time of 10 months. Median morphine milliequivalents were 20 pre-procedure and 0 post-procedure.Conclusion: We were able to show significant reductions in pain scores and opioid consumption, which suggests that minimally invasive posterior SIJ utilizing a novel implant and technique may be a viable treatment option to salvage pain relief in this patient population. Further, the favorable safety profile of this posterior technique uniquely positions it to be an appropriate first-line surgical therapy.Keywords: sacroiliac joint pain, posterior SIJ fusion, lateral SIJ fusion, salvage, low back pain

Alaa Abd-Elsayed,1 Nomen Azeem,2 Pooja Chopra,3 Ryan S D’Souza,4 Dawood Sayed,5 Timothy Deer6 1Department of Anesthesiology, University of Wisconsin, Madison, WI, USA; 2Florida Spine & Pain Specialists, Tampa, FL, USA; 3Bux Pain Management, Danville, KY, USA; 4Department of Anesthesiology and Perioperative Medicine, Mayo Clinic Hospital, Rochester, MN, USA; 5Department of Pain Medicine, University of Kansas Medical Center, Kansas City, KS, USA; 6The Spine and Nerve Centers, Charleston, WV, USACorrespondence: Alaa Abd-Elsayed, Department of Anesthesiology University of Wisconsin Madison, WI, USA, Email alaaawny@hotmail.comObjective: The objective of this study was to survey current clinical practice related to lumbar radiofrequency (RFA) for the treatment of zygapophyseal (facet)-mediated low back pain.Methods: Survey questions regarding the clinical practice of lumbar RFA were created and piloted by the American Society of Pain and Neuroscience (ASPN) leadership. After revision for clarity, health-care professionals worldwide who hold membership status within the ASPN Society and who offer lumbar RFA in their clinical practice were recruited to participate in this online survey. All responses were tabulated and summarized descriptively.Results: A total of 329 participants responded in the survey. Most participants specialized in anesthesiology (68.4%) and physical medicine and rehabilitation (21.8%) and had been practicing pain management for more than five years (70.5%). Of physician respondents, 27.5% did not complete an Accreditation Council for Graduate Medical Education (ACGME)-accredited pain medicine fellowship and 16.5% were not board-certified in pain medicine. The majority of providers (69.7%) reported that they perform two diagnostic medial branch blocks prior to proceeding with lumbar RFA. Bupivacaine 0.5% was the most common medication utilized for both the first (37.4%) and second (37.1%) diagnostic blocks. There were 32.6% of total respondents who reported not utilizing contrast dye when performing diagnostic blocks. The vast majority of providers (91.4%) reported using conventional RFA for lumbar medial branch neurotomy.Conclusion: This survey study provides a summary of the application of lumbar RFA for the treatment of axial low back pain in the real-world setting. We highlight a significant portion of providers who perform lumbar RFA yet do not have pain fellowship training at an ACGME-accredited institution or do not maintain current pain medicine board certification. We also report deviations from standard practice, specifically the type of local anesthetic used for comparative diagnostic blocks and the omission of contrast injection during diagnostic blocks.Keywords: radiofrequency ablation, low back pain, medial branch block, survey, clinical practice

Timothy R Deer,1 Adam Rupp,2 Ryan Budwany,3 Christopher J Bovinet,4 John W Chatas,5 Stephen T Pyles,6 Nomen Azeem,7 Sean Li,8 Ramana Naidu,9 Ajay Antony,10 Jonathan M Hagedorn,11 Dawood Sayed12 1The Spine & Nerve Centers of the Virginias, Charleston, WV, USA; 2Department of Physical Medicine and Rehabilitation, University of Kansas Medical Center, Kansas City, KS, USA; 3West Virginia University, Charleston, WV, USA; 4The Spine Center of Southeast Georgia, Brunswick, GA, USA; 5Michigan Pain Specialists, Ypsilanti, MI, USA; 6Pain Treatment Centers, Ocala, FL, USA; 7Florida Spine & Pain Specialists, Riverview, FL, USA; 8Premier Pain Centers, Shrewsbury, NJ, USA; 9California Orthopedics & Spine, Larkspur, CA, USA; 10The Orthopaedic Institute, Gainesville, FL, USA; 11Department of Anesthesiology and Perioperative Medicine, Division of Pain Medicine, Mayo Clinic, Rochester, MN, USA; 12Department of Anesthesiology, University of Kansas Medical Center, Kansas City, KS, USACorrespondence: Timothy R DeerThe Spine & Nerve Centers of the Virginias, Charleston, WV, 25301, USATel +1 304-347-6120Email doctdeer@aol.comBackground: Sacroiliac joint (SIJ) pain is a common cause of low back pain, a problem experienced by two-thirds of adults in the United States population. Traditionally, the management of persistent SIJ-related pain has involved conservative therapies (physical therapy, topical medications, oral anti-inflammatory medications), interventional therapies (SIJ steroid injections or ablation), and surgery (SIJ fusion; open and lateral approach). Recent advancements in technology have paved the way for SIJ fusion via a posterior approach, which aims to minimize complications and enhance recovery.Objective: The purpose of this study is to introduce the concept of the posterior approach to SIJ fusion as a feasible adjunct and salvage technique for patients with inadequate pain relief from other minimally invasive surgical procedures, and to validate its efficacy through a retrospective multicenter data analysis.Design: Multicenter retrospective observational study.Methods: Patients with refractory SIJ pain were treated by interventional pain physicians at one of the eight different pain management centers. All patients underwent posterior SIJ fusion via the LinQTM sacroiliac fusion procedure. Demographical data were collected, in addition to patient-reported pain relief.Results: A total of 111 patients were included in the study and underwent posterior SIJ fusion for refractory SIJ-related pain following the use of spinal cord stimulation (SCS), interspinous spacer (ISS), intrathecal drug delivery (IDDS), and/or minimally invasive lumbar decompression (MILD). Overall, the mean patient reported pain relief following posterior SIJ fusion was 67.6%. In patients with a history of failed back surgery syndrome, the mean patient reported pain relief was 76.5%.Conclusion: In this retrospective case series of patients with continued intolerable pain following SCS, ISS, IDDS, or MILD, a novel posterior SIJ fusion device provided significant pain relief in a salvage manner. These early results suggest that this intervention may be a therapeutic option to consider in these patients.Keywords: sacroiliac joint pain, posterior SIJ fusion, salvage, spinal cord stimulation, lumbar decompression

Sayed D, Grider J, Strand N, et al. J Pain Res. 2022;15:3729-3832. The authors have advised that there is an error in Table 32 on page 3797. Row six Gilligan et al 2021, fourth column level of evidence, the text “I-C” should read “I-A”. The correct Table 32 is as follows. Table 32 Evidence Summary for Multifidus Activation via Medial Branch Nerve Stimulation The authors apologize for this error.

The dynamics of charged particle in the vicinity of event horizon of a rotating charged black hole (BH) with gravitomagnetic charge from a class of vector-tensor theories of modified gravity immersed in an axially symmetric magnetic field (Bfield) has been studied. The presence of Bfield reduces the radii of innermost stable circular orbit (ISCO) of charged particle and the opposite phenomenon occurs due the parameter β which describes the deviation of modified gravity considered here from the usual Einstein-Maxwell gravity also acts to increase the radius of ISCO. Angular momentum also plays the role regarding the motion of particle which implies that larger the angular momentum easier for a particle to escape. We study the stability of orbits using Lyapunov characteristic exponent which implies more stability in the presence of Bfield. Generally, in the presence of Bfield it is easier for a particle to escape than its absence. We find twist in the trajectories of charged particles close to event horizon due to spin of BH in the presence of Bfield and there is no twist in the absence of it. Finally, we comment on possible utilization of our findings for the relativistic jets and magnetohydrodynamical out flows.

In this work, a collimated helium beam was used to activate a thiol-poly(ethylene glycol) (SH-PEG) monolayer on gold to selectively capture proteins in the exposed regions. Protein patterns were formed at high throughput by exposing a stencil mask placed in proximity to the PEG-coated surface to a broad beam of helium particles, followed by incubation in a protein solution. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) spectra showed that SH-PEG molecules remain attached to gold after exposure to beam doses of 1.5-60 µC/cm(2) and incubation in PBS buffer for one hour, as evidenced by the presence of characteristic ether and methoxy peaks at 1120 cm(-1) and 2870 cm(-1), respectively. X-ray Photoelectron Spectroscopy (XPS) spectra showed that increasing beam doses destroy ether (C-O) bonds in PEG molecules as evidenced by the decrease in carbon C1s peak at 286.6 eV and increased alkyl (C-C) signal at 284.6 eV. XPS spectra also demonstrated protein capture on beam-exposed PEG regions through the appearance of a nitrogen N1s peak at 400 eV and carbon C1s peak at 288 eV binding energies, while the unexposed PEG areas remained protein-free. The characteristic activities of avidin and horseradish peroxidase were preserved after attachment on beam-exposed regions. Protein patterns created using a 35 µm mesh mask were visualized by localized formation of insoluble diformazan precipitates by alkaline phosphatase conversion of its substrate bromochloroindoyl phosphate-nitroblue tetrazolium (BCIP-NBT) and by avidin binding of biotinylated antibodies conjugated on 100 nm gold nanoparticles (AuNP). Patterns created using a mask with smaller 300 nm openings were detected by specific binding of 40 nm AuNP probes and by localized HRP-mediated deposition of silver nanoparticles. Corresponding BSA-passivated negative controls showed very few bound AuNP probes and little to no enzymatic formation of diformazan precipitates or silver nanoparticles.

Ion Beam Aperture Array Lithography was applied to top-down fabrication of large dense (10(8)-10(9) particles/cm(2)) arrays of uniform micron-scale particles at rates hundreds of times faster than electron beam lithography. In this process, a large array of helium ion beamlets is formed when a stencil mask containing an array of circular openings is illuminated by a broad beam of energetic (5-8 keV) ions, and is used to write arrays of specific repetitive patterns. A commercial 5-micrometer metal mesh was used as a stencil mask; the mesh size was adjusted by shrinking the stencil openings using conformal sputter-deposition of copper. Thermal evaporation from multiple sources was utilized to form magnetic particles of varied size and thickness, including alternating layers of gold and permalloy. Evaporation of permalloy layers in the presence of a magnetic field allowed creation of particles with uniform magnetic properties and pre-determined magnetization direction. The magnetic properties of the resulting particles were characterized by Vibrating Sample Magnetometry. Since the orientation of the particles on the substrate before release into suspension is known, the orientation-dependent magnetic properties of the particles could be determined.

Raman scattering investigations based on density functional theory (DFT) calculations were performed to explore the vibrational modes of wurtzite structured CdS nanoparticles (NPs). The calculations were performed to obtain the Raman spectra for the CdS containing 2, 4, 8 and 12 atoms to study the size dependence. Several vibrational modes indicating stretching and bending features related to Cd and S atoms were observed. Modifications of the frequency and intensity of different Raman modes with an increase in number of atoms in NPs are discussed in detail. It is found that the frequency of the CdS symmetric stretching mode of vibration shows a consistent red shift and that of CdS anti‐symmetric stretching shows a consistent blue shift with the increase in the number of atoms. Hydrogen atoms were added in order to make the closed shell configuration and saturate the NPs as per the requisite for calculating the Raman spectra. This produced some additional modes of vibration related to hydrogen atoms. The SH stretching mode showed a consistent red shift and the CdH stretching mode showed a consistent blue shift with an increase in the number of atoms in NPs. The results generated are found to be in close agreement with the literature. The observed red shift in different modes is assigned to stimulated Raman stretching and blue shift is ascribed to the coherent anti‐stokes Raman scattering.