[{"data":1,"prerenderedAt":432},["ShallowReactive",2],{"blog-/blog/what-is-spr":3},{"id":4,"title":5,"author":6,"body":7,"date":417,"description":418,"draft":419,"extension":420,"image":421,"meta":422,"navigation":423,"path":424,"seo":425,"stem":426,"tags":427,"__hash__":431},"blog/blog/what-is-spr.md","What is Surface Plasmon Resonance?","Adam",{"type":8,"value":9,"toc":410},"minimark",[10,15,35,38,45,49,52,86,249,256,260,263,319,322,330,336,340,343,364,367,371,374,400,403,406],[11,12,14],"h2",{"id":13},"the-gold-standard-for-binding-kinetics","The gold standard for binding kinetics",[16,17,18,19,23,24,27,28,30,31,34],"p",{},"Surface Plasmon Resonance (SPR) is a label-free, real-time technique for measuring molecular interactions. It tells you not just ",[20,21,22],"em",{},"whether"," two molecules bind, but ",[20,25,26],{},"how fast"," they associate, ",[20,29,26],{}," they dissociate, and ",[20,32,33],{},"how tightly"," they hold on.",[16,36,37],{},"In drug discovery, these kinetic parameters are critical. A drug candidate might bind its target with high affinity, but if the kinetics are wrong -- too slow to associate, too fast to dissociate -- it may fail in the clinic.",[39,40,42],"callout",{"type":41},"info",[16,43,44],{},"SPR measures changes in refractive index near a gold surface as molecules bind and unbind. No fluorescent labels. No radioactive tracers. Just physics.",[11,46,48],{"id":47},"how-spr-works","How SPR works",[16,50,51],{},"At its core, SPR exploits the physics of light interacting with a thin gold film:",[53,54,55,63,70,77,83],"ol",{},[56,57,58,62],"li",{},[59,60,61],"strong",{},"Polarized light"," hits a gold-coated sensor surface at a specific angle",[56,64,65,66,69],{},"At the ",[59,67,68],{},"resonance angle",", energy transfers to surface plasmons (collective electron oscillations)",[56,71,72,73,76],{},"This creates a ",[59,74,75],{},"dip in reflected light"," at a precise angle",[56,78,79,80],{},"When molecules bind to the surface, the ",[59,81,82],{},"local refractive index changes",[56,84,85],{},"The resonance angle shifts, and this shift is measured in real-time",[87,88,93],"pre",{"className":89,"code":90,"language":91,"meta":92,"style":92},"language-python shiki shiki-themes 2026 Dark 2026 Dark","# Simplified binding response calculation\ndef spr_response(kon, koff, concentration, time, rmax):\n    \"\"\"Calculate SPR response using 1:1 Langmuir model.\"\"\"\n    kobs = kon * concentration + koff\n    req = rmax * (kon * concentration) / (kon * concentration + koff)\n    return req * (1 - math.exp(-kobs * time))\n","python","",[94,95,96,105,148,155,179,214],"code",{"__ignoreMap":92},[97,98,101],"span",{"class":99,"line":100},"line",1,[97,102,104],{"class":103},"sI3U9","# Simplified binding response calculation\n",[97,106,108,112,116,120,124,127,130,132,135,137,140,142,145],{"class":99,"line":107},2,[97,109,111],{"class":110},"srH4v","def",[97,113,115],{"class":114},"sYGIp"," spr_response",[97,117,119],{"class":118},"snv8h","(",[97,121,123],{"class":122},"s_i6V","kon",[97,125,126],{"class":118},", ",[97,128,129],{"class":122},"koff",[97,131,126],{"class":118},[97,133,134],{"class":122},"concentration",[97,136,126],{"class":118},[97,138,139],{"class":122},"time",[97,141,126],{"class":118},[97,143,144],{"class":122},"rmax",[97,146,147],{"class":118},"):\n",[97,149,151],{"class":99,"line":150},3,[97,152,154],{"class":153},"skZ57","    \"\"\"Calculate SPR response using 1:1 Langmuir model.\"\"\"\n",[97,156,158,161,164,167,170,173,176],{"class":99,"line":157},4,[97,159,160],{"class":118},"    kobs ",[97,162,163],{"class":110},"=",[97,165,166],{"class":118}," kon ",[97,168,169],{"class":110},"*",[97,171,172],{"class":118}," concentration ",[97,174,175],{"class":110},"+",[97,177,178],{"class":118}," koff\n",[97,180,182,185,187,190,192,195,197,200,203,205,207,209,211],{"class":99,"line":181},5,[97,183,184],{"class":118},"    req ",[97,186,163],{"class":110},[97,188,189],{"class":118}," rmax ",[97,191,169],{"class":110},[97,193,194],{"class":118}," (kon ",[97,196,169],{"class":110},[97,198,199],{"class":118}," concentration) ",[97,201,202],{"class":110},"/",[97,204,194],{"class":118},[97,206,169],{"class":110},[97,208,172],{"class":118},[97,210,175],{"class":110},[97,212,213],{"class":118}," koff)\n",[97,215,217,220,223,225,228,232,235,238,241,244,246],{"class":99,"line":216},6,[97,218,219],{"class":110},"    return",[97,221,222],{"class":118}," req ",[97,224,169],{"class":110},[97,226,227],{"class":118}," (",[97,229,231],{"class":230},"sEQcL","1",[97,233,234],{"class":110}," -",[97,236,237],{"class":118}," math.exp(",[97,239,240],{"class":110},"-",[97,242,243],{"class":118},"kobs ",[97,245,169],{"class":110},[97,247,248],{"class":118}," time))\n",[16,250,251,252,255],{},"The result is a ",[59,253,254],{},"sensorgram"," -- a plot of response units (RU) over time that shows the complete binding event: baseline, association, steady-state, and dissociation.",[11,257,259],{"id":258},"key-parameters-from-spr","Key parameters from SPR",[16,261,262],{},"From a single experiment, SPR delivers three fundamental binding parameters:",[264,265,266,282],"table",{},[267,268,269],"thead",{},[270,271,272,276,279],"tr",{},[273,274,275],"th",{},"Parameter",[273,277,278],{},"Symbol",[273,280,281],{},"What it tells you",[283,284,285,297,308],"tbody",{},[270,286,287,291,294],{},[288,289,290],"td",{},"Association rate",[288,292,293],{},"k_on",[288,295,296],{},"How fast molecules bind",[270,298,299,302,305],{},[288,300,301],{},"Dissociation rate",[288,303,304],{},"k_off",[288,306,307],{},"How fast molecules release",[270,309,310,313,316],{},[288,311,312],{},"Equilibrium dissociation constant",[288,314,315],{},"K_D",[288,317,318],{},"Overall binding affinity",[16,320,321],{},"These parameters are related by a simple equation:",[87,323,328],{"className":324,"code":326,"language":327},[325],"language-text","K_D = k_off / k_on\n","text",[94,329,326],{"__ignoreMap":92},[39,331,333],{"type":332},"tip",[16,334,335],{},"A low K_D means tight binding. But two molecules can have the same K_D with very different kinetics. SPR reveals the full picture.",[11,337,339],{"id":338},"why-spr-matters-for-drug-discovery","Why SPR matters for drug discovery",[16,341,342],{},"Affinity alone doesn't predict drug efficacy. The kinetics matter:",[344,345,346,352,358],"ul",{},[56,347,348,351],{},[59,349,350],{},"Slow k_off"," (long residence time) often correlates with better in vivo efficacy",[56,353,354,357],{},[59,355,356],{},"Fast k_on"," improves target engagement under physiological conditions",[56,359,360,363],{},[59,361,362],{},"Kinetic selectivity"," can distinguish between closely related targets",[16,365,366],{},"SPR provides this kinetic resolution without perturbing the molecules being studied. No labels means no steric interference, no quenching artifacts, and no false negatives from label placement.",[11,368,370],{"id":369},"where-spr-is-heading","Where SPR is heading",[16,372,373],{},"The next generation of SPR instruments will be defined by:",[344,375,376,382,388,394],{},[56,377,378,381],{},[59,379,380],{},"Automation"," -- removing manual sample preparation and injection bottlenecks",[56,383,384,387],{},[59,385,386],{},"Intelligence"," -- real-time data quality monitoring and adaptive experiment control",[56,389,390,393],{},[59,391,392],{},"Throughput"," -- measuring hundreds of interactions per day without sacrificing data quality",[56,395,396,399],{},[59,397,398],{},"Accessibility"," -- making kinetic characterization available earlier in the discovery pipeline",[16,401,402],{},"The instruments of tomorrow won't just measure binding. They'll understand the experiment, optimize conditions on the fly, and deliver publication-ready results with minimal human intervention.",[16,404,405],{},"That's the vision driving Instromeda.",[407,408,409],"style",{},"html pre.shiki code .sI3U9, html code.shiki .sI3U9{--shiki-default:#8B949E;--shiki-dark:#8B949E}html pre.shiki code .srH4v, html code.shiki .srH4v{--shiki-default:#FF7B72;--shiki-dark:#FF7B72}html pre.shiki code .sYGIp, html code.shiki .sYGIp{--shiki-default:#D2A8FF;--shiki-dark:#D2A8FF}html pre.shiki code .snv8h, html code.shiki .snv8h{--shiki-default:#BBBEBF;--shiki-dark:#BBBEBF}html pre.shiki code .s_i6V, html code.shiki .s_i6V{--shiki-default:#C9D1D9;--shiki-dark:#C9D1D9}html pre.shiki code .skZ57, html code.shiki .skZ57{--shiki-default:#A5D6FF;--shiki-dark:#A5D6FF}html pre.shiki code .sEQcL, html code.shiki .sEQcL{--shiki-default:#79C0FF;--shiki-dark:#79C0FF}html .default .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}html.dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}",{"title":92,"searchDepth":107,"depth":107,"links":411},[412,413,414,415,416],{"id":13,"depth":107,"text":14},{"id":47,"depth":107,"text":48},{"id":258,"depth":107,"text":259},{"id":338,"depth":107,"text":339},{"id":369,"depth":107,"text":370},"2025-05-20","A primer on SPR technology - how it works, why it matters for drug discovery, and where the field is heading.",false,"md",null,{},true,"/blog/what-is-spr",{"title":5,"description":418},"blog/what-is-spr",[428,429,430],"SPR","biophysics","drug-discovery","QJJrGtgTSblExfKtr1O8munhWc_6XHdON0iVqc-RHeA",1780474229837]