diff --git a/application/api/controller/Production.php b/application/api/controller/Production.php
index e05b064..0e2d2c3 100644
--- a/application/api/controller/Production.php
+++ b/application/api/controller/Production.php
@@ -2612,12 +2612,12 @@ class Production extends Base
         // 处理上标
         if (isset($style['vertAlign']) && $style['vertAlign'] === 'superscript') {
             // LaTeX上标需要考虑嵌套，用{}包裹内容
-            $content = "$^{{$content}}$";
+            $content = '$^{{'.$content.'}}$';
         }
 
         // 处理下标
         if (isset($style['vertAlign']) && $style['vertAlign'] === 'subscript') {
-            $content = "$_{{$content}}$";
+            $content = '$_{{'.$content.'}}$';
         }
 
         return $content;